[SPARK-9613] [CORE] Ban use of JavaConversions and migrate all existing uses to JavaConverters

Replace `JavaConversions` implicits with `JavaConverters` Most occurrences I've seen so far are necessary conversions; a few have been avoidable. None are in critical code as far as I see, yet. Author: Sean Owen <sowen@cloudera.com> Closes #8033 from srowen/SPARK-9613.
author: Sean Owen <sowen@cloudera.com> 2015-08-25 12:33:13 +0100
committer: Sean Owen <sowen@cloudera.com> 2015-08-25 12:33:13 +0100
commit: 69c9c177160e32a2fbc9b36ecc52156077fca6fc (patch)
tree: 57345aaf19c3149038bfca5c4ddccf33d41bdd5b
parent: 7f1e507bf7e82bff323c5dec3c1ee044687c4173 (diff)
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171 files changed, 863 insertions, 880 deletions
diff --git a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java
index 2389c28b28..fdb309e365 100644
--- a/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java
+++ b/core/src/main/java/org/apache/spark/shuffle/unsafe/UnsafeShuffleWriter.java
@@ -24,7 +24,7 @@ import java.util.Iterator;
 
 import scala.Option;
 import scala.Product2;
-import scala.collection.JavaConversions;
+import scala.collection.JavaConverters;
 import scala.collection.immutable.Map;
 import scala.reflect.ClassTag;
 import scala.reflect.ClassTag$;
@@ -160,7 +160,7 @@ public class UnsafeShuffleWriter<K, V> extends ShuffleWriter<K, V> {
    */
   @VisibleForTesting
   public void write(Iterator<Product2<K, V>> records) throws IOException {
-    write(JavaConversions.asScalaIterator(records));
+    write(JavaConverters.asScalaIteratorConverter(records).asScala());
   }
 
   @Override
diff --git a/core/src/main/scala/org/apache/spark/MapOutputTracker.scala b/core/src/main/scala/org/apache/spark/MapOutputTracker.scala
index 92218832d2..a387592783 100644
--- a/core/src/main/scala/org/apache/spark/MapOutputTracker.scala
+++ b/core/src/main/scala/org/apache/spark/MapOutputTracker.scala
@@ -21,8 +21,8 @@ import java.io._
 import java.util.concurrent.ConcurrentHashMap
 import java.util.zip.{GZIPInputStream, GZIPOutputStream}
 
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet, Map}
-import scala.collection.JavaConversions._
 import scala.reflect.ClassTag
 
 import org.apache.spark.rpc.{RpcEndpointRef, RpcEnv, RpcCallContext, RpcEndpoint}
@@ -398,7 +398,7 @@ private[spark] class MapOutputTrackerMaster(conf: SparkConf)
  */
 private[spark] class MapOutputTrackerWorker(conf: SparkConf) extends MapOutputTracker(conf) {
   protected val mapStatuses: Map[Int, Array[MapStatus]] =
-    new ConcurrentHashMap[Int, Array[MapStatus]]
+    new ConcurrentHashMap[Int, Array[MapStatus]]().asScala
 }
 
 private[spark] object MapOutputTracker extends Logging {
diff --git a/core/src/main/scala/org/apache/spark/SSLOptions.scala b/core/src/main/scala/org/apache/spark/SSLOptions.scala
index 32df42d57d..3b9c885bf9 100644
--- a/core/src/main/scala/org/apache/spark/SSLOptions.scala
+++ b/core/src/main/scala/org/apache/spark/SSLOptions.scala
@@ -17,9 +17,11 @@
 
 package org.apache.spark
 
-import java.io.{File, FileInputStream}
-import java.security.{KeyStore, NoSuchAlgorithmException}
-import javax.net.ssl.{KeyManager, KeyManagerFactory, SSLContext, TrustManager, TrustManagerFactory}
+import java.io.File
+import java.security.NoSuchAlgorithmException
+import javax.net.ssl.SSLContext
+
+import scala.collection.JavaConverters._
 
 import com.typesafe.config.{Config, ConfigFactory, ConfigValueFactory}
 import org.eclipse.jetty.util.ssl.SslContextFactory
@@ -79,7 +81,6 @@ private[spark] case class SSLOptions(
    * object. It can be used then to compose the ultimate Akka configuration.
    */
   def createAkkaConfig: Option[Config] = {
-    import scala.collection.JavaConversions._
     if (enabled) {
       Some(ConfigFactory.empty()
         .withValue("akka.remote.netty.tcp.security.key-store",
@@ -97,7 +98,7 @@ private[spark] case class SSLOptions(
         .withValue("akka.remote.netty.tcp.security.protocol",
           ConfigValueFactory.fromAnyRef(protocol.getOrElse("")))
         .withValue("akka.remote.netty.tcp.security.enabled-algorithms",
-          ConfigValueFactory.fromIterable(supportedAlgorithms.toSeq))
+          ConfigValueFactory.fromIterable(supportedAlgorithms.asJava))
         .withValue("akka.remote.netty.tcp.enable-ssl",
           ConfigValueFactory.fromAnyRef(true)))
     } else {
diff --git a/core/src/main/scala/org/apache/spark/SparkContext.scala b/core/src/main/scala/org/apache/spark/SparkContext.scala
index 9849aff85d..f3da04a7f5 100644
--- a/core/src/main/scala/org/apache/spark/SparkContext.scala
+++ b/core/src/main/scala/org/apache/spark/SparkContext.scala
@@ -26,8 +26,8 @@ import java.util.{Arrays, Properties, UUID}
 import java.util.concurrent.atomic.{AtomicReference, AtomicBoolean, AtomicInteger}
 import java.util.UUID.randomUUID
 
+import scala.collection.JavaConverters._
 import scala.collection.{Map, Set}
-import scala.collection.JavaConversions._
 import scala.collection.generic.Growable
 import scala.collection.mutable.HashMap
 import scala.reflect.{ClassTag, classTag}
@@ -1546,7 +1546,7 @@ class SparkContext(config: SparkConf) extends Logging with ExecutorAllocationCli
   def getAllPools: Seq[Schedulable] = {
     assertNotStopped()
     // TODO(xiajunluan): We should take nested pools into account
-    taskScheduler.rootPool.schedulableQueue.toSeq
+    taskScheduler.rootPool.schedulableQueue.asScala.toSeq
   }
 
   /**
diff --git a/core/src/main/scala/org/apache/spark/TestUtils.scala b/core/src/main/scala/org/apache/spark/TestUtils.scala
index a1ebbecf93..888763a3e8 100644
--- a/core/src/main/scala/org/apache/spark/TestUtils.scala
+++ b/core/src/main/scala/org/apache/spark/TestUtils.scala
@@ -19,11 +19,12 @@ package org.apache.spark
 
 import java.io.{ByteArrayInputStream, File, FileInputStream, FileOutputStream}
 import java.net.{URI, URL}
+import java.nio.charset.StandardCharsets
+import java.util.Arrays
 import java.util.jar.{JarEntry, JarOutputStream}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
-import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.{ByteStreams, Files}
 import javax.tools.{JavaFileObject, SimpleJavaFileObject, ToolProvider}
 
@@ -71,7 +72,7 @@ private[spark] object TestUtils {
     files.foreach { case (k, v) =>
       val entry = new JarEntry(k)
       jarStream.putNextEntry(entry)
-      ByteStreams.copy(new ByteArrayInputStream(v.getBytes(UTF_8)), jarStream)
+      ByteStreams.copy(new ByteArrayInputStream(v.getBytes(StandardCharsets.UTF_8)), jarStream)
     }
     jarStream.close()
     jarFile.toURI.toURL
@@ -125,7 +126,7 @@ private[spark] object TestUtils {
     } else {
       Seq()
     }
-    compiler.getTask(null, null, null, options, null, Seq(sourceFile)).call()
+    compiler.getTask(null, null, null, options.asJava, null, Arrays.asList(sourceFile)).call()
 
     val fileName = className + ".class"
     val result = new File(fileName)
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaHadoopRDD.scala b/core/src/main/scala/org/apache/spark/api/java/JavaHadoopRDD.scala
index 0ae0b4ec04..891bcddeac 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaHadoopRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaHadoopRDD.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.api.java
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
 import org.apache.hadoop.mapred.InputSplit
@@ -37,7 +37,7 @@ class JavaHadoopRDD[K, V](rdd: HadoopRDD[K, V])
   def mapPartitionsWithInputSplit[R](
       f: JFunction2[InputSplit, java.util.Iterator[(K, V)], java.util.Iterator[R]],
       preservesPartitioning: Boolean = false): JavaRDD[R] = {
-    new JavaRDD(rdd.mapPartitionsWithInputSplit((a, b) => f.call(a, asJavaIterator(b)),
+    new JavaRDD(rdd.mapPartitionsWithInputSplit((a, b) => f.call(a, b.asJava).asScala,
       preservesPartitioning)(fakeClassTag))(fakeClassTag)
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaNewHadoopRDD.scala b/core/src/main/scala/org/apache/spark/api/java/JavaNewHadoopRDD.scala
index ec4f3964d7..0f49279f3e 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaNewHadoopRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaNewHadoopRDD.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.api.java
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
 import org.apache.hadoop.mapreduce.InputSplit
@@ -37,7 +37,7 @@ class JavaNewHadoopRDD[K, V](rdd: NewHadoopRDD[K, V])
   def mapPartitionsWithInputSplit[R](
       f: JFunction2[InputSplit, java.util.Iterator[(K, V)], java.util.Iterator[R]],
       preservesPartitioning: Boolean = false): JavaRDD[R] = {
-    new JavaRDD(rdd.mapPartitionsWithInputSplit((a, b) => f.call(a, asJavaIterator(b)),
+    new JavaRDD(rdd.mapPartitionsWithInputSplit((a, b) => f.call(a, b.asJava).asScala,
       preservesPartitioning)(fakeClassTag))(fakeClassTag)
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala b/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
index 8441bb3a30..fb787979c1 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaPairRDD.scala
@@ -20,7 +20,7 @@ package org.apache.spark.api.java
 import java.util.{Comparator, List => JList, Map => JMap}
 import java.lang.{Iterable => JIterable}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.language.implicitConversions
 import scala.reflect.ClassTag
 
@@ -142,7 +142,7 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
   def sampleByKey(withReplacement: Boolean,
       fractions: JMap[K, Double],
       seed: Long): JavaPairRDD[K, V] =
-    new JavaPairRDD[K, V](rdd.sampleByKey(withReplacement, fractions, seed))
+    new JavaPairRDD[K, V](rdd.sampleByKey(withReplacement, fractions.asScala, seed))
 
   /**
    * Return a subset of this RDD sampled by key (via stratified sampling).
@@ -173,7 +173,7 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
   def sampleByKeyExact(withReplacement: Boolean,
       fractions: JMap[K, Double],
       seed: Long): JavaPairRDD[K, V] =
-    new JavaPairRDD[K, V](rdd.sampleByKeyExact(withReplacement, fractions, seed))
+    new JavaPairRDD[K, V](rdd.sampleByKeyExact(withReplacement, fractions.asScala, seed))
 
   /**
    * ::Experimental::
@@ -768,7 +768,7 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
    * Return the list of values in the RDD for key `key`. This operation is done efficiently if the
    * RDD has a known partitioner by only searching the partition that the key maps to.
    */
-  def lookup(key: K): JList[V] = seqAsJavaList(rdd.lookup(key))
+  def lookup(key: K): JList[V] = rdd.lookup(key).asJava
 
   /** Output the RDD to any Hadoop-supported file system. */
   def saveAsHadoopFile[F <: OutputFormat[_, _]](
@@ -987,30 +987,27 @@ class JavaPairRDD[K, V](val rdd: RDD[(K, V)])
 object JavaPairRDD {
   private[spark]
   def groupByResultToJava[K: ClassTag, T](rdd: RDD[(K, Iterable[T])]): RDD[(K, JIterable[T])] = {
-    rddToPairRDDFunctions(rdd).mapValues(asJavaIterable)
+    rddToPairRDDFunctions(rdd).mapValues(_.asJava)
   }
 
   private[spark]
   def cogroupResultToJava[K: ClassTag, V, W](
       rdd: RDD[(K, (Iterable[V], Iterable[W]))]): RDD[(K, (JIterable[V], JIterable[W]))] = {
-    rddToPairRDDFunctions(rdd).mapValues(x => (asJavaIterable(x._1), asJavaIterable(x._2)))
+    rddToPairRDDFunctions(rdd).mapValues(x => (x._1.asJava, x._2.asJava))
   }
 
   private[spark]
   def cogroupResult2ToJava[K: ClassTag, V, W1, W2](
       rdd: RDD[(K, (Iterable[V], Iterable[W1], Iterable[W2]))])
       : RDD[(K, (JIterable[V], JIterable[W1], JIterable[W2]))] = {
-    rddToPairRDDFunctions(rdd)
-      .mapValues(x => (asJavaIterable(x._1), asJavaIterable(x._2), asJavaIterable(x._3)))
+    rddToPairRDDFunctions(rdd).mapValues(x => (x._1.asJava, x._2.asJava, x._3.asJava))
   }
 
   private[spark]
   def cogroupResult3ToJava[K: ClassTag, V, W1, W2, W3](
       rdd: RDD[(K, (Iterable[V], Iterable[W1], Iterable[W2], Iterable[W3]))])
   : RDD[(K, (JIterable[V], JIterable[W1], JIterable[W2], JIterable[W3]))] = {
-    rddToPairRDDFunctions(rdd)
-      .mapValues(x =>
-        (asJavaIterable(x._1), asJavaIterable(x._2), asJavaIterable(x._3), asJavaIterable(x._4)))
+    rddToPairRDDFunctions(rdd).mapValues(x => (x._1.asJava, x._2.asJava, x._3.asJava, x._4.asJava))
   }
 
   def fromRDD[K: ClassTag, V: ClassTag](rdd: RDD[(K, V)]): JavaPairRDD[K, V] = {
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala b/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala
index c582488f16..fc817cdd6a 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala
@@ -21,7 +21,6 @@ import java.{lang => jl}
 import java.lang.{Iterable => JIterable, Long => JLong}
 import java.util.{Comparator, List => JList, Iterator => JIterator}
 
-import scala.collection.JavaConversions._
 import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
@@ -59,10 +58,10 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
   def rdd: RDD[T]
 
   @deprecated("Use partitions() instead.", "1.1.0")
-  def splits: JList[Partition] = new java.util.ArrayList(rdd.partitions.toSeq)
+  def splits: JList[Partition] = rdd.partitions.toSeq.asJava
 
   /** Set of partitions in this RDD. */
-  def partitions: JList[Partition] = new java.util.ArrayList(rdd.partitions.toSeq)
+  def partitions: JList[Partition] = rdd.partitions.toSeq.asJava
 
   /** The partitioner of this RDD. */
   def partitioner: Optional[Partitioner] = JavaUtils.optionToOptional(rdd.partitioner)
@@ -82,7 +81,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * subclasses of RDD.
    */
   def iterator(split: Partition, taskContext: TaskContext): java.util.Iterator[T] =
-    asJavaIterator(rdd.iterator(split, taskContext))
+    rdd.iterator(split, taskContext).asJava
 
   // Transformations (return a new RDD)
 
@@ -99,7 +98,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
   def mapPartitionsWithIndex[R](
       f: JFunction2[jl.Integer, java.util.Iterator[T], java.util.Iterator[R]],
       preservesPartitioning: Boolean = false): JavaRDD[R] =
-    new JavaRDD(rdd.mapPartitionsWithIndex(((a, b) => f(a, asJavaIterator(b))),
+    new JavaRDD(rdd.mapPartitionsWithIndex((a, b) => f.call(a, b.asJava).asScala,
         preservesPartitioning)(fakeClassTag))(fakeClassTag)
 
   /**
@@ -153,7 +152,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    */
   def mapPartitions[U](f: FlatMapFunction[java.util.Iterator[T], U]): JavaRDD[U] = {
     def fn: (Iterator[T]) => Iterator[U] = {
-      (x: Iterator[T]) => asScalaIterator(f.call(asJavaIterator(x)).iterator())
+      (x: Iterator[T]) => f.call(x.asJava).iterator().asScala
     }
     JavaRDD.fromRDD(rdd.mapPartitions(fn)(fakeClassTag[U]))(fakeClassTag[U])
   }
@@ -164,7 +163,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
   def mapPartitions[U](f: FlatMapFunction[java.util.Iterator[T], U],
       preservesPartitioning: Boolean): JavaRDD[U] = {
     def fn: (Iterator[T]) => Iterator[U] = {
-      (x: Iterator[T]) => asScalaIterator(f.call(asJavaIterator(x)).iterator())
+      (x: Iterator[T]) => f.call(x.asJava).iterator().asScala
     }
     JavaRDD.fromRDD(
       rdd.mapPartitions(fn, preservesPartitioning)(fakeClassTag[U]))(fakeClassTag[U])
@@ -175,7 +174,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    */
   def mapPartitionsToDouble(f: DoubleFlatMapFunction[java.util.Iterator[T]]): JavaDoubleRDD = {
     def fn: (Iterator[T]) => Iterator[jl.Double] = {
-      (x: Iterator[T]) => asScalaIterator(f.call(asJavaIterator(x)).iterator())
+      (x: Iterator[T]) => f.call(x.asJava).iterator().asScala
     }
     new JavaDoubleRDD(rdd.mapPartitions(fn).map((x: jl.Double) => x.doubleValue()))
   }
@@ -186,7 +185,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
   def mapPartitionsToPair[K2, V2](f: PairFlatMapFunction[java.util.Iterator[T], K2, V2]):
   JavaPairRDD[K2, V2] = {
     def fn: (Iterator[T]) => Iterator[(K2, V2)] = {
-      (x: Iterator[T]) => asScalaIterator(f.call(asJavaIterator(x)).iterator())
+      (x: Iterator[T]) => f.call(x.asJava).iterator().asScala
     }
     JavaPairRDD.fromRDD(rdd.mapPartitions(fn))(fakeClassTag[K2], fakeClassTag[V2])
   }
@@ -197,7 +196,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
   def mapPartitionsToDouble(f: DoubleFlatMapFunction[java.util.Iterator[T]],
       preservesPartitioning: Boolean): JavaDoubleRDD = {
     def fn: (Iterator[T]) => Iterator[jl.Double] = {
-      (x: Iterator[T]) => asScalaIterator(f.call(asJavaIterator(x)).iterator())
+      (x: Iterator[T]) => f.call(x.asJava).iterator().asScala
     }
     new JavaDoubleRDD(rdd.mapPartitions(fn, preservesPartitioning)
       .map(x => x.doubleValue()))
@@ -209,7 +208,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
   def mapPartitionsToPair[K2, V2](f: PairFlatMapFunction[java.util.Iterator[T], K2, V2],
       preservesPartitioning: Boolean): JavaPairRDD[K2, V2] = {
     def fn: (Iterator[T]) => Iterator[(K2, V2)] = {
-      (x: Iterator[T]) => asScalaIterator(f.call(asJavaIterator(x)).iterator())
+      (x: Iterator[T]) => f.call(x.asJava).iterator().asScala
     }
     JavaPairRDD.fromRDD(
       rdd.mapPartitions(fn, preservesPartitioning))(fakeClassTag[K2], fakeClassTag[V2])
@@ -219,14 +218,14 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * Applies a function f to each partition of this RDD.
    */
   def foreachPartition(f: VoidFunction[java.util.Iterator[T]]) {
-    rdd.foreachPartition((x => f.call(asJavaIterator(x))))
+    rdd.foreachPartition((x => f.call(x.asJava)))
   }
 
   /**
    * Return an RDD created by coalescing all elements within each partition into an array.
    */
   def glom(): JavaRDD[JList[T]] =
-    new JavaRDD(rdd.glom().map(x => new java.util.ArrayList[T](x.toSeq)))
+    new JavaRDD(rdd.glom().map(_.toSeq.asJava))
 
   /**
    * Return the Cartesian product of this RDD and another one, that is, the RDD of all pairs of
@@ -266,13 +265,13 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * Return an RDD created by piping elements to a forked external process.
    */
   def pipe(command: JList[String]): JavaRDD[String] =
-    rdd.pipe(asScalaBuffer(command))
+    rdd.pipe(command.asScala)
 
   /**
    * Return an RDD created by piping elements to a forked external process.
    */
   def pipe(command: JList[String], env: java.util.Map[String, String]): JavaRDD[String] =
-    rdd.pipe(asScalaBuffer(command), mapAsScalaMap(env))
+    rdd.pipe(command.asScala, env.asScala)
 
   /**
    * Zips this RDD with another one, returning key-value pairs with the first element in each RDD,
@@ -294,8 +293,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
       other: JavaRDDLike[U, _],
       f: FlatMapFunction2[java.util.Iterator[T], java.util.Iterator[U], V]): JavaRDD[V] = {
     def fn: (Iterator[T], Iterator[U]) => Iterator[V] = {
-      (x: Iterator[T], y: Iterator[U]) => asScalaIterator(
-        f.call(asJavaIterator(x), asJavaIterator(y)).iterator())
+      (x: Iterator[T], y: Iterator[U]) => f.call(x.asJava, y.asJava).iterator().asScala
     }
     JavaRDD.fromRDD(
       rdd.zipPartitions(other.rdd)(fn)(other.classTag, fakeClassTag[V]))(fakeClassTag[V])
@@ -333,22 +331,16 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
   /**
    * Return an array that contains all of the elements in this RDD.
    */
-  def collect(): JList[T] = {
-    import scala.collection.JavaConversions._
-    val arr: java.util.Collection[T] = rdd.collect().toSeq
-    new java.util.ArrayList(arr)
-  }
+  def collect(): JList[T] =
+    rdd.collect().toSeq.asJava
 
   /**
    * Return an iterator that contains all of the elements in this RDD.
    *
    * The iterator will consume as much memory as the largest partition in this RDD.
    */
-  def toLocalIterator(): JIterator[T] = {
-     import scala.collection.JavaConversions._
-     rdd.toLocalIterator
-  }
-
+  def toLocalIterator(): JIterator[T] =
+     asJavaIteratorConverter(rdd.toLocalIterator).asJava
 
   /**
    * Return an array that contains all of the elements in this RDD.
@@ -363,9 +355,8 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
   def collectPartitions(partitionIds: Array[Int]): Array[JList[T]] = {
     // This is useful for implementing `take` from other language frontends
     // like Python where the data is serialized.
-    import scala.collection.JavaConversions._
     val res = context.runJob(rdd, (it: Iterator[T]) => it.toArray, partitionIds)
-    res.map(x => new java.util.ArrayList(x.toSeq)).toArray
+    res.map(_.toSeq.asJava)
   }
 
   /**
@@ -489,20 +480,14 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * it will be slow if a lot of partitions are required. In that case, use collect() to get the
    * whole RDD instead.
    */
-  def take(num: Int): JList[T] = {
-    import scala.collection.JavaConversions._
-    val arr: java.util.Collection[T] = rdd.take(num).toSeq
-    new java.util.ArrayList(arr)
-  }
+  def take(num: Int): JList[T] =
+    rdd.take(num).toSeq.asJava
 
   def takeSample(withReplacement: Boolean, num: Int): JList[T] =
     takeSample(withReplacement, num, Utils.random.nextLong)
 
-  def takeSample(withReplacement: Boolean, num: Int, seed: Long): JList[T] = {
-    import scala.collection.JavaConversions._
-    val arr: java.util.Collection[T] = rdd.takeSample(withReplacement, num, seed).toSeq
-    new java.util.ArrayList(arr)
-  }
+  def takeSample(withReplacement: Boolean, num: Int, seed: Long): JList[T] =
+    rdd.takeSample(withReplacement, num, seed).toSeq.asJava
 
   /**
    * Return the first element in this RDD.
@@ -582,10 +567,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * @return an array of top elements
    */
   def top(num: Int, comp: Comparator[T]): JList[T] = {
-    import scala.collection.JavaConversions._
-    val topElems = rdd.top(num)(Ordering.comparatorToOrdering(comp))
-    val arr: java.util.Collection[T] = topElems.toSeq
-    new java.util.ArrayList(arr)
+    rdd.top(num)(Ordering.comparatorToOrdering(comp)).toSeq.asJava
   }
 
   /**
@@ -607,10 +589,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * @return an array of top elements
    */
   def takeOrdered(num: Int, comp: Comparator[T]): JList[T] = {
-    import scala.collection.JavaConversions._
-    val topElems = rdd.takeOrdered(num)(Ordering.comparatorToOrdering(comp))
-    val arr: java.util.Collection[T] = topElems.toSeq
-    new java.util.ArrayList(arr)
+    rdd.takeOrdered(num)(Ordering.comparatorToOrdering(comp)).toSeq.asJava
   }
 
   /**
@@ -696,7 +675,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * applies a function f to each partition of this RDD.
    */
   def foreachPartitionAsync(f: VoidFunction[java.util.Iterator[T]]): JavaFutureAction[Void] = {
-    new JavaFutureActionWrapper[Unit, Void](rdd.foreachPartitionAsync(x => f.call(x)),
+    new JavaFutureActionWrapper[Unit, Void](rdd.foreachPartitionAsync(x => f.call(x.asJava)),
       { x => null.asInstanceOf[Void] })
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala b/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala
index 02e49a853c..609496ccdf 100644
--- a/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala
+++ b/core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala
@@ -21,8 +21,7 @@ import java.io.Closeable
 import java.util
 import java.util.{Map => JMap}
 
-import scala.collection.JavaConversions
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.language.implicitConversions
 import scala.reflect.ClassTag
 
@@ -104,7 +103,7 @@ class JavaSparkContext(val sc: SparkContext)
    */
   def this(master: String, appName: String, sparkHome: String, jars: Array[String],
       environment: JMap[String, String]) =
-    this(new SparkContext(master, appName, sparkHome, jars.toSeq, environment, Map()))
+    this(new SparkContext(master, appName, sparkHome, jars.toSeq, environment.asScala, Map()))
 
   private[spark] val env = sc.env
 
@@ -118,7 +117,7 @@ class JavaSparkContext(val sc: SparkContext)
 
   def appName: String = sc.appName
 
-  def jars: util.List[String] = sc.jars
+  def jars: util.List[String] = sc.jars.asJava
 
   def startTime: java.lang.Long = sc.startTime
 
@@ -142,7 +141,7 @@ class JavaSparkContext(val sc: SparkContext)
   /** Distribute a local Scala collection to form an RDD. */
   def parallelize[T](list: java.util.List[T], numSlices: Int): JavaRDD[T] = {
     implicit val ctag: ClassTag[T] = fakeClassTag
-    sc.parallelize(JavaConversions.asScalaBuffer(list), numSlices)
+    sc.parallelize(list.asScala, numSlices)
   }
 
   /** Get an RDD that has no partitions or elements. */
@@ -161,7 +160,7 @@ class JavaSparkContext(val sc: SparkContext)
   : JavaPairRDD[K, V] = {
     implicit val ctagK: ClassTag[K] = fakeClassTag
     implicit val ctagV: ClassTag[V] = fakeClassTag
-    JavaPairRDD.fromRDD(sc.parallelize(JavaConversions.asScalaBuffer(list), numSlices))
+    JavaPairRDD.fromRDD(sc.parallelize(list.asScala, numSlices))
   }
 
   /** Distribute a local Scala collection to form an RDD. */
@@ -170,8 +169,7 @@ class JavaSparkContext(val sc: SparkContext)
 
   /** Distribute a local Scala collection to form an RDD. */
   def parallelizeDoubles(list: java.util.List[java.lang.Double], numSlices: Int): JavaDoubleRDD =
-    JavaDoubleRDD.fromRDD(sc.parallelize(JavaConversions.asScalaBuffer(list).map(_.doubleValue()),
-      numSlices))
+    JavaDoubleRDD.fromRDD(sc.parallelize(list.asScala.map(_.doubleValue()), numSlices))
 
   /** Distribute a local Scala collection to form an RDD. */
   def parallelizeDoubles(list: java.util.List[java.lang.Double]): JavaDoubleRDD =
@@ -519,7 +517,7 @@ class JavaSparkContext(val sc: SparkContext)
 
   /** Build the union of two or more RDDs. */
   override def union[T](first: JavaRDD[T], rest: java.util.List[JavaRDD[T]]): JavaRDD[T] = {
-    val rdds: Seq[RDD[T]] = (Seq(first) ++ asScalaBuffer(rest)).map(_.rdd)
+    val rdds: Seq[RDD[T]] = (Seq(first) ++ rest.asScala).map(_.rdd)
     implicit val ctag: ClassTag[T] = first.classTag
     sc.union(rdds)
   }
@@ -527,7 +525,7 @@ class JavaSparkContext(val sc: SparkContext)
   /** Build the union of two or more RDDs. */
   override def union[K, V](first: JavaPairRDD[K, V], rest: java.util.List[JavaPairRDD[K, V]])
       : JavaPairRDD[K, V] = {
-    val rdds: Seq[RDD[(K, V)]] = (Seq(first) ++ asScalaBuffer(rest)).map(_.rdd)
+    val rdds: Seq[RDD[(K, V)]] = (Seq(first) ++ rest.asScala).map(_.rdd)
     implicit val ctag: ClassTag[(K, V)] = first.classTag
     implicit val ctagK: ClassTag[K] = first.kClassTag
     implicit val ctagV: ClassTag[V] = first.vClassTag
@@ -536,7 +534,7 @@ class JavaSparkContext(val sc: SparkContext)
 
   /** Build the union of two or more RDDs. */
   override def union(first: JavaDoubleRDD, rest: java.util.List[JavaDoubleRDD]): JavaDoubleRDD = {
-    val rdds: Seq[RDD[Double]] = (Seq(first) ++ asScalaBuffer(rest)).map(_.srdd)
+    val rdds: Seq[RDD[Double]] = (Seq(first) ++ rest.asScala).map(_.srdd)
     new JavaDoubleRDD(sc.union(rdds))
   }
 
diff --git a/core/src/main/scala/org/apache/spark/api/python/PythonHadoopUtil.scala b/core/src/main/scala/org/apache/spark/api/python/PythonHadoopUtil.scala
index b959b683d1..a7dfa1d257 100644
--- a/core/src/main/scala/org/apache/spark/api/python/PythonHadoopUtil.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/PythonHadoopUtil.scala
@@ -17,15 +17,17 @@
 
 package org.apache.spark.api.python
 
-import org.apache.spark.broadcast.Broadcast
-import org.apache.spark.rdd.RDD
-import org.apache.spark.util.{SerializableConfiguration, Utils}
-import org.apache.spark.{Logging, SparkException}
+import scala.collection.JavaConverters._
+import scala.util.{Failure, Success, Try}
+
 import org.apache.hadoop.conf.Configuration
 import org.apache.hadoop.io._
-import scala.util.{Failure, Success, Try}
-import org.apache.spark.annotation.Experimental
 
+import org.apache.spark.{Logging, SparkException}
+import org.apache.spark.annotation.Experimental
+import org.apache.spark.broadcast.Broadcast
+import org.apache.spark.rdd.RDD
+import org.apache.spark.util.{SerializableConfiguration, Utils}
 
 /**
  * :: Experimental ::
@@ -68,7 +70,6 @@ private[python] class WritableToJavaConverter(
    * object representation
    */
   private def convertWritable(writable: Writable): Any = {
-    import collection.JavaConversions._
     writable match {
       case iw: IntWritable => iw.get()
       case dw: DoubleWritable => dw.get()
@@ -89,9 +90,7 @@ private[python] class WritableToJavaConverter(
         aw.get().map(convertWritable(_))
       case mw: MapWritable =>
         val map = new java.util.HashMap[Any, Any]()
-        mw.foreach { case (k, v) =>
-          map.put(convertWritable(k), convertWritable(v))
-        }
+        mw.asScala.foreach { case (k, v) => map.put(convertWritable(k), convertWritable(v)) }
         map
       case w: Writable => WritableUtils.clone(w, conf.value.value)
       case other => other
@@ -122,7 +121,6 @@ private[python] class JavaToWritableConverter extends Converter[Any, Writable] {
    * supported out-of-the-box.
    */
   private def convertToWritable(obj: Any): Writable = {
-    import collection.JavaConversions._
     obj match {
       case i: java.lang.Integer => new IntWritable(i)
       case d: java.lang.Double => new DoubleWritable(d)
@@ -134,7 +132,7 @@ private[python] class JavaToWritableConverter extends Converter[Any, Writable] {
       case null => NullWritable.get()
       case map: java.util.Map[_, _] =>
         val mapWritable = new MapWritable()
-        map.foreach { case (k, v) =>
+        map.asScala.foreach { case (k, v) =>
           mapWritable.put(convertToWritable(k), convertToWritable(v))
         }
         mapWritable
@@ -161,9 +159,8 @@ private[python] object PythonHadoopUtil {
    * Convert a [[java.util.Map]] of properties to a [[org.apache.hadoop.conf.Configuration]]
    */
   def mapToConf(map: java.util.Map[String, String]): Configuration = {
-    import collection.JavaConversions._
     val conf = new Configuration()
-    map.foreach{ case (k, v) => conf.set(k, v) }
+    map.asScala.foreach { case (k, v) => conf.set(k, v) }
     conf
   }
 
@@ -172,9 +169,8 @@ private[python] object PythonHadoopUtil {
    * any matching keys in left
    */
   def mergeConfs(left: Configuration, right: Configuration): Configuration = {
-    import collection.JavaConversions._
     val copy = new Configuration(left)
-    right.iterator().foreach(entry => copy.set(entry.getKey, entry.getValue))
+    right.asScala.foreach(entry => copy.set(entry.getKey, entry.getValue))
     copy
   }
 
diff --git a/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala b/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
index 2a56bf28d7..b4d152b336 100644
--- a/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala
@@ -21,7 +21,7 @@ import java.io._
 import java.net._
 import java.util.{Collections, ArrayList => JArrayList, List => JList, Map => JMap}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.language.existentials
 
@@ -66,11 +66,11 @@ private[spark] class PythonRDD(
     val env = SparkEnv.get
     val localdir = env.blockManager.diskBlockManager.localDirs.map(
       f => f.getPath()).mkString(",")
-    envVars += ("SPARK_LOCAL_DIRS" -> localdir) // it's also used in monitor thread
+    envVars.put("SPARK_LOCAL_DIRS", localdir) // it's also used in monitor thread
     if (reuse_worker) {
-      envVars += ("SPARK_REUSE_WORKER" -> "1")
+      envVars.put("SPARK_REUSE_WORKER", "1")
     }
-    val worker: Socket = env.createPythonWorker(pythonExec, envVars.toMap)
+    val worker: Socket = env.createPythonWorker(pythonExec, envVars.asScala.toMap)
     // Whether is the worker released into idle pool
     @volatile var released = false
 
@@ -150,7 +150,7 @@ private[spark] class PythonRDD(
               // Check whether the worker is ready to be re-used.
               if (stream.readInt() == SpecialLengths.END_OF_STREAM) {
                 if (reuse_worker) {
-                  env.releasePythonWorker(pythonExec, envVars.toMap, worker)
+                  env.releasePythonWorker(pythonExec, envVars.asScala.toMap, worker)
                   released = true
                 }
               }
@@ -217,13 +217,13 @@ private[spark] class PythonRDD(
         // sparkFilesDir
         PythonRDD.writeUTF(SparkFiles.getRootDirectory, dataOut)
         // Python includes (*.zip and *.egg files)
-        dataOut.writeInt(pythonIncludes.length)
-        for (include <- pythonIncludes) {
+        dataOut.writeInt(pythonIncludes.size())
+        for (include <- pythonIncludes.asScala) {
           PythonRDD.writeUTF(include, dataOut)
         }
         // Broadcast variables
         val oldBids = PythonRDD.getWorkerBroadcasts(worker)
-        val newBids = broadcastVars.map(_.id).toSet
+        val newBids = broadcastVars.asScala.map(_.id).toSet
         // number of different broadcasts
         val toRemove = oldBids.diff(newBids)
         val cnt = toRemove.size + newBids.diff(oldBids).size
@@ -233,7 +233,7 @@ private[spark] class PythonRDD(
           dataOut.writeLong(- bid - 1)  // bid >= 0
           oldBids.remove(bid)
         }
-        for (broadcast <- broadcastVars) {
+        for (broadcast <- broadcastVars.asScala) {
           if (!oldBids.contains(broadcast.id)) {
             // send new broadcast
             dataOut.writeLong(broadcast.id)
@@ -287,7 +287,7 @@ private[spark] class PythonRDD(
       if (!context.isCompleted) {
         try {
           logWarning("Incomplete task interrupted: Attempting to kill Python Worker")
-          env.destroyPythonWorker(pythonExec, envVars.toMap, worker)
+          env.destroyPythonWorker(pythonExec, envVars.asScala.toMap, worker)
         } catch {
           case e: Exception =>
             logError("Exception when trying to kill worker", e)
@@ -358,10 +358,10 @@ private[spark] object PythonRDD extends Logging {
     type ByteArray = Array[Byte]
     type UnrolledPartition = Array[ByteArray]
     val allPartitions: Array[UnrolledPartition] =
-      sc.runJob(rdd, (x: Iterator[ByteArray]) => x.toArray, partitions)
+      sc.runJob(rdd, (x: Iterator[ByteArray]) => x.toArray, partitions.asScala)
     val flattenedPartition: UnrolledPartition = Array.concat(allPartitions: _*)
     serveIterator(flattenedPartition.iterator,
-      s"serve RDD ${rdd.id} with partitions ${partitions.mkString(",")}")
+      s"serve RDD ${rdd.id} with partitions ${partitions.asScala.mkString(",")}")
   }
 
   /**
@@ -819,7 +819,7 @@ private class PythonAccumulatorParam(@transient serverHost: String, serverPort:
       val in = socket.getInputStream
       val out = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream, bufferSize))
       out.writeInt(val2.size)
-      for (array <- val2) {
+      for (array <- val2.asScala) {
         out.writeInt(array.length)
         out.write(array)
       }
diff --git a/core/src/main/scala/org/apache/spark/api/python/PythonUtils.scala b/core/src/main/scala/org/apache/spark/api/python/PythonUtils.scala
index 90dacaeb93..31e534f160 100644
--- a/core/src/main/scala/org/apache/spark/api/python/PythonUtils.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/PythonUtils.scala
@@ -17,10 +17,10 @@
 
 package org.apache.spark.api.python
 
-import java.io.{File}
+import java.io.File
 import java.util.{List => JList}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 
 import org.apache.spark.SparkContext
@@ -51,7 +51,14 @@ private[spark] object PythonUtils {
    * Convert list of T into seq of T (for calling API with varargs)
    */
   def toSeq[T](vs: JList[T]): Seq[T] = {
-    vs.toList.toSeq
+    vs.asScala
+  }
+
+  /**
+   * Convert list of T into a (Scala) List of T
+   */
+  def toList[T](vs: JList[T]): List[T] = {
+    vs.asScala.toList
   }
 
   /**
@@ -65,6 +72,6 @@ private[spark] object PythonUtils {
    * Convert java map of K, V into Map of K, V (for calling API with varargs)
    */
   def toScalaMap[K, V](jm: java.util.Map[K, V]): Map[K, V] = {
-    jm.toMap
+    jm.asScala.toMap
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/api/python/PythonWorkerFactory.scala b/core/src/main/scala/org/apache/spark/api/python/PythonWorkerFactory.scala
index e314408c06..7039b734d2 100644
--- a/core/src/main/scala/org/apache/spark/api/python/PythonWorkerFactory.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/PythonWorkerFactory.scala
@@ -19,9 +19,10 @@ package org.apache.spark.api.python
 
 import java.io.{DataOutputStream, DataInputStream, InputStream, OutputStreamWriter}
 import java.net.{InetAddress, ServerSocket, Socket, SocketException}
+import java.util.Arrays
 
 import scala.collection.mutable
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark._
 import org.apache.spark.util.{RedirectThread, Utils}
@@ -108,9 +109,9 @@ private[spark] class PythonWorkerFactory(pythonExec: String, envVars: Map[String
       serverSocket = new ServerSocket(0, 1, InetAddress.getByAddress(Array(127, 0, 0, 1)))
 
       // Create and start the worker
-      val pb = new ProcessBuilder(Seq(pythonExec, "-m", "pyspark.worker"))
+      val pb = new ProcessBuilder(Arrays.asList(pythonExec, "-m", "pyspark.worker"))
       val workerEnv = pb.environment()
-      workerEnv.putAll(envVars)
+      workerEnv.putAll(envVars.asJava)
       workerEnv.put("PYTHONPATH", pythonPath)
       // This is equivalent to setting the -u flag; we use it because ipython doesn't support -u:
       workerEnv.put("PYTHONUNBUFFERED", "YES")
@@ -151,9 +152,9 @@ private[spark] class PythonWorkerFactory(pythonExec: String, envVars: Map[String
 
       try {
         // Create and start the daemon
-        val pb = new ProcessBuilder(Seq(pythonExec, "-m", "pyspark.daemon"))
+        val pb = new ProcessBuilder(Arrays.asList(pythonExec, "-m", "pyspark.daemon"))
         val workerEnv = pb.environment()
-        workerEnv.putAll(envVars)
+        workerEnv.putAll(envVars.asJava)
         workerEnv.put("PYTHONPATH", pythonPath)
         // This is equivalent to setting the -u flag; we use it because ipython doesn't support -u:
         workerEnv.put("PYTHONUNBUFFERED", "YES")
diff --git a/core/src/main/scala/org/apache/spark/api/python/SerDeUtil.scala b/core/src/main/scala/org/apache/spark/api/python/SerDeUtil.scala
index 1f1debcf84..fd27276e70 100644
--- a/core/src/main/scala/org/apache/spark/api/python/SerDeUtil.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/SerDeUtil.scala
@@ -22,7 +22,6 @@ import java.util.{ArrayList => JArrayList}
 
 import org.apache.spark.api.java.JavaRDD
 
-import scala.collection.JavaConversions._
 import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.util.Failure
@@ -214,7 +213,7 @@ private[spark] object SerDeUtil extends Logging {
         new AutoBatchedPickler(cleaned)
       } else {
         val pickle = new Pickler
-        cleaned.grouped(batchSize).map(batched => pickle.dumps(seqAsJavaList(batched)))
+        cleaned.grouped(batchSize).map(batched => pickle.dumps(batched.asJava))
       }
     }
   }
diff --git a/core/src/main/scala/org/apache/spark/api/python/WriteInputFormatTestDataGenerator.scala b/core/src/main/scala/org/apache/spark/api/python/WriteInputFormatTestDataGenerator.scala
index 8f30ff9202..ee1fb056f0 100644
--- a/core/src/main/scala/org/apache/spark/api/python/WriteInputFormatTestDataGenerator.scala
+++ b/core/src/main/scala/org/apache/spark/api/python/WriteInputFormatTestDataGenerator.scala
@@ -20,6 +20,8 @@ package org.apache.spark.api.python
 import java.io.{DataOutput, DataInput}
 import java.{util => ju}
 
+import scala.collection.JavaConverters._
+
 import com.google.common.base.Charsets.UTF_8
 
 import org.apache.hadoop.io._
@@ -62,10 +64,9 @@ private[python] class TestInputKeyConverter extends Converter[Any, Any] {
 }
 
 private[python] class TestInputValueConverter extends Converter[Any, Any] {
-  import collection.JavaConversions._
   override def convert(obj: Any): ju.List[Double] = {
     val m = obj.asInstanceOf[MapWritable]
-    seqAsJavaList(m.keySet.map(w => w.asInstanceOf[DoubleWritable].get()).toSeq)
+    m.keySet.asScala.map(_.asInstanceOf[DoubleWritable].get()).toSeq.asJava
   }
 }
 
@@ -76,9 +77,8 @@ private[python] class TestOutputKeyConverter extends Converter[Any, Any] {
 }
 
 private[python] class TestOutputValueConverter extends Converter[Any, Any] {
-  import collection.JavaConversions._
   override def convert(obj: Any): DoubleWritable = {
-    new DoubleWritable(obj.asInstanceOf[java.util.Map[Double, _]].keySet().head)
+    new DoubleWritable(obj.asInstanceOf[java.util.Map[Double, _]].keySet().iterator().next())
   }
 }
 
diff --git a/core/src/main/scala/org/apache/spark/api/r/RRDD.scala b/core/src/main/scala/org/apache/spark/api/r/RRDD.scala
index 1cf2824f86..9d5bbb5d60 100644
--- a/core/src/main/scala/org/apache/spark/api/r/RRDD.scala
+++ b/core/src/main/scala/org/apache/spark/api/r/RRDD.scala
@@ -19,9 +19,10 @@ package org.apache.spark.api.r
 
 import java.io._
 import java.net.{InetAddress, ServerSocket}
+import java.util.Arrays
 import java.util.{Map => JMap}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.io.Source
 import scala.reflect.ClassTag
 import scala.util.Try
@@ -365,11 +366,11 @@ private[r] object RRDD {
       sparkConf.setIfMissing("spark.master", "local")
     }
 
-    for ((name, value) <- sparkEnvirMap) {
-      sparkConf.set(name.asInstanceOf[String], value.asInstanceOf[String])
+    for ((name, value) <- sparkEnvirMap.asScala) {
+      sparkConf.set(name.toString, value.toString)
     }
-    for ((name, value) <- sparkExecutorEnvMap) {
-      sparkConf.setExecutorEnv(name.asInstanceOf[String], value.asInstanceOf[String])
+    for ((name, value) <- sparkExecutorEnvMap.asScala) {
+      sparkConf.setExecutorEnv(name.toString, value.toString)
     }
 
     val jsc = new JavaSparkContext(sparkConf)
@@ -395,7 +396,7 @@ private[r] object RRDD {
     val rOptions = "--vanilla"
     val rLibDir = RUtils.sparkRPackagePath(isDriver = false)
     val rExecScript = rLibDir + "/SparkR/worker/" + script
-    val pb = new ProcessBuilder(List(rCommand, rOptions, rExecScript))
+    val pb = new ProcessBuilder(Arrays.asList(rCommand, rOptions, rExecScript))
     // Unset the R_TESTS environment variable for workers.
     // This is set by R CMD check as startup.Rs
     // (http://svn.r-project.org/R/trunk/src/library/tools/R/testing.R)
diff --git a/core/src/main/scala/org/apache/spark/api/r/RUtils.scala b/core/src/main/scala/org/apache/spark/api/r/RUtils.scala
index 427b2bc7cb..9e807cc52f 100644
--- a/core/src/main/scala/org/apache/spark/api/r/RUtils.scala
+++ b/core/src/main/scala/org/apache/spark/api/r/RUtils.scala
@@ -18,8 +18,7 @@
 package org.apache.spark.api.r
 
 import java.io.File
-
-import scala.collection.JavaConversions._
+import java.util.Arrays
 
 import org.apache.spark.{SparkEnv, SparkException}
 
@@ -68,7 +67,7 @@ private[spark] object RUtils {
   /** Check if R is installed before running tests that use R commands. */
   def isRInstalled: Boolean = {
     try {
-      val builder = new ProcessBuilder(Seq("R", "--version"))
+      val builder = new ProcessBuilder(Arrays.asList("R", "--version"))
       builder.start().waitFor() == 0
     } catch {
       case e: Exception => false
diff --git a/core/src/main/scala/org/apache/spark/api/r/SerDe.scala b/core/src/main/scala/org/apache/spark/api/r/SerDe.scala
index 3c89f24473..dbbbcf40c1 100644
--- a/core/src/main/scala/org/apache/spark/api/r/SerDe.scala
+++ b/core/src/main/scala/org/apache/spark/api/r/SerDe.scala
@@ -20,7 +20,7 @@ package org.apache.spark.api.r
 import java.io.{DataInputStream, DataOutputStream}
 import java.sql.{Timestamp, Date, Time}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 /**
  * Utility functions to serialize, deserialize objects to / from R
@@ -165,7 +165,7 @@ private[spark] object SerDe {
         val valueType = readObjectType(in)
         readTypedObject(in, valueType)
       })
-      mapAsJavaMap(keys.zip(values).toMap)
+      keys.zip(values).toMap.asJava
     } else {
       new java.util.HashMap[Object, Object]()
     }
diff --git a/core/src/main/scala/org/apache/spark/broadcast/TorrentBroadcast.scala b/core/src/main/scala/org/apache/spark/broadcast/TorrentBroadcast.scala
index a0c9b5e63c..7e3764d802 100644
--- a/core/src/main/scala/org/apache/spark/broadcast/TorrentBroadcast.scala
+++ b/core/src/main/scala/org/apache/spark/broadcast/TorrentBroadcast.scala
@@ -20,7 +20,7 @@ package org.apache.spark.broadcast
 import java.io._
 import java.nio.ByteBuffer
 
-import scala.collection.JavaConversions.asJavaEnumeration
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 import scala.util.Random
 
@@ -210,7 +210,7 @@ private object TorrentBroadcast extends Logging {
       compressionCodec: Option[CompressionCodec]): T = {
     require(blocks.nonEmpty, "Cannot unblockify an empty array of blocks")
     val is = new SequenceInputStream(
-      asJavaEnumeration(blocks.iterator.map(block => new ByteBufferInputStream(block))))
+      blocks.iterator.map(new ByteBufferInputStream(_)).asJavaEnumeration)
     val in: InputStream = compressionCodec.map(c => c.compressedInputStream(is)).getOrElse(is)
     val ser = serializer.newInstance()
     val serIn = ser.deserializeStream(in)
diff --git a/core/src/main/scala/org/apache/spark/deploy/ExternalShuffleService.scala b/core/src/main/scala/org/apache/spark/deploy/ExternalShuffleService.scala
index 22ef701d83..6840a3ae83 100644
--- a/core/src/main/scala/org/apache/spark/deploy/ExternalShuffleService.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/ExternalShuffleService.scala
@@ -19,13 +19,13 @@ package org.apache.spark.deploy
 
 import java.util.concurrent.CountDownLatch
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.{Logging, SparkConf, SecurityManager}
 import org.apache.spark.network.TransportContext
 import org.apache.spark.network.netty.SparkTransportConf
 import org.apache.spark.network.sasl.SaslServerBootstrap
-import org.apache.spark.network.server.TransportServer
+import org.apache.spark.network.server.{TransportServerBootstrap, TransportServer}
 import org.apache.spark.network.shuffle.ExternalShuffleBlockHandler
 import org.apache.spark.network.util.TransportConf
 import org.apache.spark.util.Utils
@@ -67,13 +67,13 @@ class ExternalShuffleService(sparkConf: SparkConf, securityManager: SecurityMana
   def start() {
     require(server == null, "Shuffle server already started")
     logInfo(s"Starting shuffle service on port $port with useSasl = $useSasl")
-    val bootstraps =
+    val bootstraps: Seq[TransportServerBootstrap] =
       if (useSasl) {
         Seq(new SaslServerBootstrap(transportConf, securityManager))
       } else {
         Nil
       }
-    server = transportContext.createServer(port, bootstraps)
+    server = transportContext.createServer(port, bootstraps.asJava)
   }
 
   /** Clean up all shuffle files associated with an application that has exited. */
diff --git a/core/src/main/scala/org/apache/spark/deploy/PythonRunner.scala b/core/src/main/scala/org/apache/spark/deploy/PythonRunner.scala
index 23d01e9cbb..d85327603f 100644
--- a/core/src/main/scala/org/apache/spark/deploy/PythonRunner.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/PythonRunner.scala
@@ -21,7 +21,7 @@ import java.net.URI
 import java.io.File
 
 import scala.collection.mutable.ArrayBuffer
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.Try
 
 import org.apache.spark.SparkUserAppException
@@ -71,7 +71,7 @@ object PythonRunner {
     val pythonPath = PythonUtils.mergePythonPaths(pathElements: _*)
 
     // Launch Python process
-    val builder = new ProcessBuilder(Seq(pythonExec, formattedPythonFile) ++ otherArgs)
+    val builder = new ProcessBuilder((Seq(pythonExec, formattedPythonFile) ++ otherArgs).asJava)
     val env = builder.environment()
     env.put("PYTHONPATH", pythonPath)
     // This is equivalent to setting the -u flag; we use it because ipython doesn't support -u:
diff --git a/core/src/main/scala/org/apache/spark/deploy/RPackageUtils.scala b/core/src/main/scala/org/apache/spark/deploy/RPackageUtils.scala
index ed1e972955..4b28866dca 100644
--- a/core/src/main/scala/org/apache/spark/deploy/RPackageUtils.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/RPackageUtils.scala
@@ -22,7 +22,7 @@ import java.util.jar.JarFile
 import java.util.logging.Level
 import java.util.zip.{ZipEntry, ZipOutputStream}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import com.google.common.io.{ByteStreams, Files}
 
@@ -110,7 +110,7 @@ private[deploy] object RPackageUtils extends Logging {
       print(s"Building R package with the command: $installCmd", printStream)
     }
     try {
-      val builder = new ProcessBuilder(installCmd)
+      val builder = new ProcessBuilder(installCmd.asJava)
       builder.redirectErrorStream(true)
       val env = builder.environment()
       env.clear()
diff --git a/core/src/main/scala/org/apache/spark/deploy/RRunner.scala b/core/src/main/scala/org/apache/spark/deploy/RRunner.scala
index c0cab22fa8..05b954ce36 100644
--- a/core/src/main/scala/org/apache/spark/deploy/RRunner.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/RRunner.scala
@@ -20,7 +20,7 @@ package org.apache.spark.deploy
 import java.io._
 import java.util.concurrent.{Semaphore, TimeUnit}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.hadoop.fs.Path
 
@@ -68,7 +68,7 @@ object RRunner {
     if (initialized.tryAcquire(backendTimeout, TimeUnit.SECONDS)) {
       // Launch R
       val returnCode = try {
-        val builder = new ProcessBuilder(Seq(rCommand, rFileNormalized) ++ otherArgs)
+        val builder = new ProcessBuilder((Seq(rCommand, rFileNormalized) ++ otherArgs).asJava)
         val env = builder.environment()
         env.put("EXISTING_SPARKR_BACKEND_PORT", sparkRBackendPort.toString)
         val rPackageDir = RUtils.sparkRPackagePath(isDriver = true)
diff --git a/core/src/main/scala/org/apache/spark/deploy/SparkCuratorUtil.scala b/core/src/main/scala/org/apache/spark/deploy/SparkCuratorUtil.scala
index b8d3993540..8d5e716e6a 100644
--- a/core/src/main/scala/org/apache/spark/deploy/SparkCuratorUtil.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/SparkCuratorUtil.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.deploy
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.curator.framework.{CuratorFramework, CuratorFrameworkFactory}
 import org.apache.curator.retry.ExponentialBackoffRetry
@@ -57,7 +57,7 @@ private[spark] object SparkCuratorUtil extends Logging {
 
   def deleteRecursive(zk: CuratorFramework, path: String) {
     if (zk.checkExists().forPath(path) != null) {
-      for (child <- zk.getChildren.forPath(path)) {
+      for (child <- zk.getChildren.forPath(path).asScala) {
         zk.delete().forPath(path + "/" + child)
       }
       zk.delete().forPath(path)
diff --git a/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala b/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
index dda4216c7e..f7723ef5bd 100644
--- a/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/SparkHadoopUtil.scala
@@ -22,7 +22,7 @@ import java.lang.reflect.Method
 import java.security.PrivilegedExceptionAction
 import java.util.{Arrays, Comparator}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.concurrent.duration._
 import scala.language.postfixOps
 import scala.util.control.NonFatal
@@ -71,7 +71,7 @@ class SparkHadoopUtil extends Logging {
   }
 
   def transferCredentials(source: UserGroupInformation, dest: UserGroupInformation) {
-    for (token <- source.getTokens()) {
+    for (token <- source.getTokens.asScala) {
       dest.addToken(token)
     }
   }
@@ -175,8 +175,8 @@ class SparkHadoopUtil extends Logging {
   }
 
   private def getFileSystemThreadStatistics(): Seq[AnyRef] = {
-    val stats = FileSystem.getAllStatistics()
-    stats.map(Utils.invoke(classOf[Statistics], _, "getThreadStatistics"))
+    FileSystem.getAllStatistics.asScala.map(
+      Utils.invoke(classOf[Statistics], _, "getThreadStatistics"))
   }
 
   private def getFileSystemThreadStatisticsMethod(methodName: String): Method = {
@@ -306,12 +306,13 @@ class SparkHadoopUtil extends Logging {
     val renewalInterval =
       sparkConf.getLong("spark.yarn.token.renewal.interval", (24 hours).toMillis)
 
-    credentials.getAllTokens.filter(_.getKind == DelegationTokenIdentifier.HDFS_DELEGATION_KIND)
+    credentials.getAllTokens.asScala
+      .filter(_.getKind == DelegationTokenIdentifier.HDFS_DELEGATION_KIND)
       .map { t =>
-      val identifier = new DelegationTokenIdentifier()
-      identifier.readFields(new DataInputStream(new ByteArrayInputStream(t.getIdentifier)))
-      (identifier.getIssueDate + fraction * renewalInterval).toLong - now
-    }.foldLeft(0L)(math.max)
+        val identifier = new DelegationTokenIdentifier()
+        identifier.readFields(new DataInputStream(new ByteArrayInputStream(t.getIdentifier)))
+        (identifier.getIssueDate + fraction * renewalInterval).toLong - now
+      }.foldLeft(0L)(math.max)
   }
 
 
diff --git a/core/src/main/scala/org/apache/spark/deploy/SparkSubmitArguments.scala b/core/src/main/scala/org/apache/spark/deploy/SparkSubmitArguments.scala
index 3f3c6627c2..18a1c52ae5 100644
--- a/core/src/main/scala/org/apache/spark/deploy/SparkSubmitArguments.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/SparkSubmitArguments.scala
@@ -23,7 +23,7 @@ import java.net.URI
 import java.util.{List => JList}
 import java.util.jar.JarFile
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{ArrayBuffer, HashMap}
 import scala.io.Source
 
@@ -94,7 +94,7 @@ private[deploy] class SparkSubmitArguments(args: Seq[String], env: Map[String, S
 
   // Set parameters from command line arguments
   try {
-    parse(args.toList)
+    parse(args.asJava)
   } catch {
     case e: IllegalArgumentException =>
       SparkSubmit.printErrorAndExit(e.getMessage())
@@ -458,7 +458,7 @@ private[deploy] class SparkSubmitArguments(args: Seq[String], env: Map[String, S
   }
 
   override protected def handleExtraArgs(extra: JList[String]): Unit = {
-    childArgs ++= extra
+    childArgs ++= extra.asScala
   }
 
   private def printUsageAndExit(exitCode: Int, unknownParam: Any = null): Unit = {
diff --git a/core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperPersistenceEngine.scala b/core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperPersistenceEngine.scala
index 563831cc6b..540e802420 100644
--- a/core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperPersistenceEngine.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/master/ZooKeeperPersistenceEngine.scala
@@ -19,7 +19,7 @@ package org.apache.spark.deploy.master
 
 import java.nio.ByteBuffer
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
 import org.apache.curator.framework.CuratorFramework
@@ -49,8 +49,8 @@ private[master] class ZooKeeperPersistenceEngine(conf: SparkConf, val serializer
   }
 
   override def read[T: ClassTag](prefix: String): Seq[T] = {
-    val file = zk.getChildren.forPath(WORKING_DIR).filter(_.startsWith(prefix))
-    file.map(deserializeFromFile[T]).flatten
+    zk.getChildren.forPath(WORKING_DIR).asScala
+      .filter(_.startsWith(prefix)).map(deserializeFromFile[T]).flatten
   }
 
   override def close() {
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/CommandUtils.scala b/core/src/main/scala/org/apache/spark/deploy/worker/CommandUtils.scala
index 45a3f43045..ce02ee203a 100644
--- a/core/src/main/scala/org/apache/spark/deploy/worker/CommandUtils.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/CommandUtils.scala
@@ -18,9 +18,8 @@
 package org.apache.spark.deploy.worker
 
 import java.io.{File, FileOutputStream, InputStream, IOException}
-import java.lang.System._
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.Map
 
 import org.apache.spark.Logging
@@ -62,7 +61,7 @@ object CommandUtils extends Logging {
     // SPARK-698: do not call the run.cmd script, as process.destroy()
     // fails to kill a process tree on Windows
     val cmd = new WorkerCommandBuilder(sparkHome, memory, command).buildCommand()
-    cmd.toSeq ++ Seq(command.mainClass) ++ command.arguments
+    cmd.asScala ++ Seq(command.mainClass) ++ command.arguments
   }
 
   /**
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/DriverRunner.scala b/core/src/main/scala/org/apache/spark/deploy/worker/DriverRunner.scala
index ec51c3d935..89159ff5e2 100644
--- a/core/src/main/scala/org/apache/spark/deploy/worker/DriverRunner.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/DriverRunner.scala
@@ -19,7 +19,7 @@ package org.apache.spark.deploy.worker
 
 import java.io._
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.Files
@@ -172,8 +172,8 @@ private[deploy] class DriverRunner(
       CommandUtils.redirectStream(process.getInputStream, stdout)
 
       val stderr = new File(baseDir, "stderr")
-      val header = "Launch Command: %s\n%s\n\n".format(
-        builder.command.mkString("\"", "\" \"", "\""), "=" * 40)
+      val formattedCommand = builder.command.asScala.mkString("\"", "\" \"", "\"")
+      val header = "Launch Command: %s\n%s\n\n".format(formattedCommand, "=" * 40)
       Files.append(header, stderr, UTF_8)
       CommandUtils.redirectStream(process.getErrorStream, stderr)
     }
@@ -229,6 +229,6 @@ private[deploy] trait ProcessBuilderLike {
 private[deploy] object ProcessBuilderLike {
   def apply(processBuilder: ProcessBuilder): ProcessBuilderLike = new ProcessBuilderLike {
     override def start(): Process = processBuilder.start()
-    override def command: Seq[String] = processBuilder.command()
+    override def command: Seq[String] = processBuilder.command().asScala
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/ExecutorRunner.scala b/core/src/main/scala/org/apache/spark/deploy/worker/ExecutorRunner.scala
index ab3fea475c..3aef0515cb 100644
--- a/core/src/main/scala/org/apache/spark/deploy/worker/ExecutorRunner.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/ExecutorRunner.scala
@@ -19,7 +19,7 @@ package org.apache.spark.deploy.worker
 
 import java.io._
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.Files
@@ -129,7 +129,8 @@ private[deploy] class ExecutorRunner(
       val builder = CommandUtils.buildProcessBuilder(appDesc.command, new SecurityManager(conf),
         memory, sparkHome.getAbsolutePath, substituteVariables)
       val command = builder.command()
-      logInfo("Launch command: " + command.mkString("\"", "\" \"", "\""))
+      val formattedCommand = command.asScala.mkString("\"", "\" \"", "\"")
+      logInfo(s"Launch command: $formattedCommand")
 
       builder.directory(executorDir)
       builder.environment.put("SPARK_EXECUTOR_DIRS", appLocalDirs.mkString(File.pathSeparator))
@@ -145,7 +146,7 @@ private[deploy] class ExecutorRunner(
 
       process = builder.start()
       val header = "Spark Executor Command: %s\n%s\n\n".format(
-        command.mkString("\"", "\" \"", "\""), "=" * 40)
+        formattedCommand, "=" * 40)
 
       // Redirect its stdout and stderr to files
       val stdout = new File(executorDir, "stdout")
diff --git a/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala b/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala
index 79b1536d94..770927c80f 100755
--- a/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala
+++ b/core/src/main/scala/org/apache/spark/deploy/worker/Worker.scala
@@ -24,7 +24,6 @@ import java.util.{UUID, Date}
 import java.util.concurrent._
 import java.util.concurrent.{Future => JFuture, ScheduledFuture => JScheduledFuture}
 
-import scala.collection.JavaConversions._
 import scala.collection.mutable.{HashMap, HashSet, LinkedHashMap}
 import scala.concurrent.ExecutionContext
 import scala.util.Random
diff --git a/core/src/main/scala/org/apache/spark/executor/Executor.scala b/core/src/main/scala/org/apache/spark/executor/Executor.scala
index 42a85e42ea..c3491bb8b1 100644
--- a/core/src/main/scala/org/apache/spark/executor/Executor.scala
+++ b/core/src/main/scala/org/apache/spark/executor/Executor.scala
@@ -23,7 +23,7 @@ import java.net.URL
 import java.nio.ByteBuffer
 import java.util.concurrent.{ConcurrentHashMap, TimeUnit}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{ArrayBuffer, HashMap}
 import scala.util.control.NonFatal
 
@@ -147,7 +147,7 @@ private[spark] class Executor(
 
   /** Returns the total amount of time this JVM process has spent in garbage collection. */
   private def computeTotalGcTime(): Long = {
-    ManagementFactory.getGarbageCollectorMXBeans.map(_.getCollectionTime).sum
+    ManagementFactory.getGarbageCollectorMXBeans.asScala.map(_.getCollectionTime).sum
   }
 
   class TaskRunner(
@@ -425,7 +425,7 @@ private[spark] class Executor(
     val tasksMetrics = new ArrayBuffer[(Long, TaskMetrics)]()
     val curGCTime = computeTotalGcTime()
 
-    for (taskRunner <- runningTasks.values()) {
+    for (taskRunner <- runningTasks.values().asScala) {
       if (taskRunner.task != null) {
         taskRunner.task.metrics.foreach { metrics =>
           metrics.updateShuffleReadMetrics()
diff --git a/core/src/main/scala/org/apache/spark/executor/ExecutorSource.scala b/core/src/main/scala/org/apache/spark/executor/ExecutorSource.scala
index 293c512f8b..d16f4a1fc4 100644
--- a/core/src/main/scala/org/apache/spark/executor/ExecutorSource.scala
+++ b/core/src/main/scala/org/apache/spark/executor/ExecutorSource.scala
@@ -19,7 +19,7 @@ package org.apache.spark.executor
 
 import java.util.concurrent.ThreadPoolExecutor
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import com.codahale.metrics.{Gauge, MetricRegistry}
 import org.apache.hadoop.fs.FileSystem
@@ -30,7 +30,7 @@ private[spark]
 class ExecutorSource(threadPool: ThreadPoolExecutor, executorId: String) extends Source {
 
   private def fileStats(scheme: String) : Option[FileSystem.Statistics] =
-    FileSystem.getAllStatistics().find(s => s.getScheme.equals(scheme))
+    FileSystem.getAllStatistics.asScala.find(s => s.getScheme.equals(scheme))
 
   private def registerFileSystemStat[T](
         scheme: String, name: String, f: FileSystem.Statistics => T, defaultValue: T) = {
diff --git a/core/src/main/scala/org/apache/spark/executor/MesosExecutorBackend.scala b/core/src/main/scala/org/apache/spark/executor/MesosExecutorBackend.scala
index cfd672e1d8..0474fd2ccc 100644
--- a/core/src/main/scala/org/apache/spark/executor/MesosExecutorBackend.scala
+++ b/core/src/main/scala/org/apache/spark/executor/MesosExecutorBackend.scala
@@ -19,7 +19,7 @@ package org.apache.spark.executor
 
 import java.nio.ByteBuffer
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.mesos.protobuf.ByteString
 import org.apache.mesos.{Executor => MesosExecutor, ExecutorDriver, MesosExecutorDriver}
@@ -28,7 +28,7 @@ import org.apache.mesos.Protos.{TaskStatus => MesosTaskStatus, _}
 import org.apache.spark.{Logging, TaskState, SparkConf, SparkEnv}
 import org.apache.spark.TaskState.TaskState
 import org.apache.spark.deploy.SparkHadoopUtil
-import org.apache.spark.scheduler.cluster.mesos.{MesosTaskLaunchData}
+import org.apache.spark.scheduler.cluster.mesos.MesosTaskLaunchData
 import org.apache.spark.util.{SignalLogger, Utils}
 
 private[spark] class MesosExecutorBackend
@@ -55,7 +55,7 @@ private[spark] class MesosExecutorBackend
       slaveInfo: SlaveInfo) {
 
     // Get num cores for this task from ExecutorInfo, created in MesosSchedulerBackend.
-    val cpusPerTask = executorInfo.getResourcesList
+    val cpusPerTask = executorInfo.getResourcesList.asScala
       .find(_.getName == "cpus")
       .map(_.getScalar.getValue.toInt)
       .getOrElse(0)
diff --git a/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala b/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala
index 6cda7772f7..a5ad47293f 100644
--- a/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala
+++ b/core/src/main/scala/org/apache/spark/input/PortableDataStream.scala
@@ -19,7 +19,7 @@ package org.apache.spark.input
 
 import java.io.{ByteArrayInputStream, ByteArrayOutputStream, DataInputStream, DataOutputStream}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import com.google.common.io.ByteStreams
 import org.apache.hadoop.conf.Configuration
@@ -44,12 +44,9 @@ private[spark] abstract class StreamFileInputFormat[T]
    * which is set through setMaxSplitSize
    */
   def setMinPartitions(context: JobContext, minPartitions: Int) {
-    val files = listStatus(context)
-    val totalLen = files.map { file =>
-      if (file.isDir) 0L else file.getLen
-    }.sum
-
-    val maxSplitSize = Math.ceil(totalLen * 1.0 / files.length).toLong
+    val files = listStatus(context).asScala
+    val totalLen = files.map(file => if (file.isDir) 0L else file.getLen).sum
+    val maxSplitSize = Math.ceil(totalLen * 1.0 / files.size).toLong
     super.setMaxSplitSize(maxSplitSize)
   }
 
diff --git a/core/src/main/scala/org/apache/spark/input/WholeTextFileInputFormat.scala b/core/src/main/scala/org/apache/spark/input/WholeTextFileInputFormat.scala
index aaef7c74ee..1ba34a1141 100644
--- a/core/src/main/scala/org/apache/spark/input/WholeTextFileInputFormat.scala
+++ b/core/src/main/scala/org/apache/spark/input/WholeTextFileInputFormat.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.input
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.hadoop.fs.Path
 import org.apache.hadoop.mapreduce.InputSplit
@@ -52,10 +52,8 @@ private[spark] class WholeTextFileInputFormat
    * which is set through setMaxSplitSize
    */
   def setMinPartitions(context: JobContext, minPartitions: Int) {
-    val files = listStatus(context)
-    val totalLen = files.map { file =>
-      if (file.isDir) 0L else file.getLen
-    }.sum
+    val files = listStatus(context).asScala
+    val totalLen = files.map(file => if (file.isDir) 0L else file.getLen).sum
     val maxSplitSize = Math.ceil(totalLen * 1.0 /
       (if (minPartitions == 0) 1 else minPartitions)).toLong
     super.setMaxSplitSize(maxSplitSize)
diff --git a/core/src/main/scala/org/apache/spark/launcher/WorkerCommandBuilder.scala b/core/src/main/scala/org/apache/spark/launcher/WorkerCommandBuilder.scala
index 9be98723ae..0c096656f9 100644
--- a/core/src/main/scala/org/apache/spark/launcher/WorkerCommandBuilder.scala
+++ b/core/src/main/scala/org/apache/spark/launcher/WorkerCommandBuilder.scala
@@ -20,7 +20,7 @@ package org.apache.spark.launcher
 import java.io.File
 import java.util.{HashMap => JHashMap, List => JList, Map => JMap}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.deploy.Command
 
@@ -32,7 +32,7 @@ import org.apache.spark.deploy.Command
 private[spark] class WorkerCommandBuilder(sparkHome: String, memoryMb: Int, command: Command)
     extends AbstractCommandBuilder {
 
-  childEnv.putAll(command.environment)
+  childEnv.putAll(command.environment.asJava)
   childEnv.put(CommandBuilderUtils.ENV_SPARK_HOME, sparkHome)
 
   override def buildCommand(env: JMap[String, String]): JList[String] = {
diff --git a/core/src/main/scala/org/apache/spark/metrics/MetricsConfig.scala b/core/src/main/scala/org/apache/spark/metrics/MetricsConfig.scala
index d7495551ad..dd2d325d87 100644
--- a/core/src/main/scala/org/apache/spark/metrics/MetricsConfig.scala
+++ b/core/src/main/scala/org/apache/spark/metrics/MetricsConfig.scala
@@ -20,6 +20,7 @@ package org.apache.spark.metrics
 import java.io.{FileInputStream, InputStream}
 import java.util.Properties
 
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.util.matching.Regex
 
@@ -58,25 +59,20 @@ private[spark] class MetricsConfig(conf: SparkConf) extends Logging {
 
     propertyCategories = subProperties(properties, INSTANCE_REGEX)
     if (propertyCategories.contains(DEFAULT_PREFIX)) {
-      import scala.collection.JavaConversions._
-
-      val defaultProperty = propertyCategories(DEFAULT_PREFIX)
-      for { (inst, prop) <- propertyCategories
-            if (inst != DEFAULT_PREFIX)
-            (k, v) <- defaultProperty
-            if (prop.getProperty(k) == null) } {
-        prop.setProperty(k, v)
+      val defaultProperty = propertyCategories(DEFAULT_PREFIX).asScala
+      for((inst, prop) <- propertyCategories if (inst != DEFAULT_PREFIX);
+          (k, v) <- defaultProperty if (prop.get(k) == null)) {
+        prop.put(k, v)
       }
     }
   }
 
   def subProperties(prop: Properties, regex: Regex): mutable.HashMap[String, Properties] = {
     val subProperties = new mutable.HashMap[String, Properties]
-    import scala.collection.JavaConversions._
-    prop.foreach { kv =>
-      if (regex.findPrefixOf(kv._1).isDefined) {
-        val regex(prefix, suffix) = kv._1
-        subProperties.getOrElseUpdate(prefix, new Properties).setProperty(suffix, kv._2)
+    prop.asScala.foreach { kv =>
+      if (regex.findPrefixOf(kv._1.toString).isDefined) {
+        val regex(prefix, suffix) = kv._1.toString
+        subProperties.getOrElseUpdate(prefix, new Properties).setProperty(suffix, kv._2.toString)
       }
     }
     subProperties
diff --git a/core/src/main/scala/org/apache/spark/network/netty/NettyBlockRpcServer.scala b/core/src/main/scala/org/apache/spark/network/netty/NettyBlockRpcServer.scala
index b089da8596..7c170a742f 100644
--- a/core/src/main/scala/org/apache/spark/network/netty/NettyBlockRpcServer.scala
+++ b/core/src/main/scala/org/apache/spark/network/netty/NettyBlockRpcServer.scala
@@ -19,7 +19,7 @@ package org.apache.spark.network.netty
 
 import java.nio.ByteBuffer
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.Logging
 import org.apache.spark.network.BlockDataManager
@@ -55,7 +55,7 @@ class NettyBlockRpcServer(
       case openBlocks: OpenBlocks =>
         val blocks: Seq[ManagedBuffer] =
           openBlocks.blockIds.map(BlockId.apply).map(blockManager.getBlockData)
-        val streamId = streamManager.registerStream(blocks.iterator)
+        val streamId = streamManager.registerStream(blocks.iterator.asJava)
         logTrace(s"Registered streamId $streamId with ${blocks.size} buffers")
         responseContext.onSuccess(new StreamHandle(streamId, blocks.size).toByteArray)
 
diff --git a/core/src/main/scala/org/apache/spark/network/netty/NettyBlockTransferService.scala b/core/src/main/scala/org/apache/spark/network/netty/NettyBlockTransferService.scala
index d650d5fe73..ff8aae9ebe 100644
--- a/core/src/main/scala/org/apache/spark/network/netty/NettyBlockTransferService.scala
+++ b/core/src/main/scala/org/apache/spark/network/netty/NettyBlockTransferService.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.network.netty
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.concurrent.{Future, Promise}
 
 import org.apache.spark.{SecurityManager, SparkConf}
@@ -58,7 +58,7 @@ class NettyBlockTransferService(conf: SparkConf, securityManager: SecurityManage
         securityManager.isSaslEncryptionEnabled()))
     }
     transportContext = new TransportContext(transportConf, rpcHandler)
-    clientFactory = transportContext.createClientFactory(clientBootstrap.toList)
+    clientFactory = transportContext.createClientFactory(clientBootstrap.toSeq.asJava)
     server = createServer(serverBootstrap.toList)
     appId = conf.getAppId
     logInfo("Server created on " + server.getPort)
@@ -67,7 +67,7 @@ class NettyBlockTransferService(conf: SparkConf, securityManager: SecurityManage
   /** Creates and binds the TransportServer, possibly trying multiple ports. */
   private def createServer(bootstraps: List[TransportServerBootstrap]): TransportServer = {
     def startService(port: Int): (TransportServer, Int) = {
-      val server = transportContext.createServer(port, bootstraps)
+      val server = transportContext.createServer(port, bootstraps.asJava)
       (server, server.getPort)
     }
 
diff --git a/core/src/main/scala/org/apache/spark/network/nio/Connection.scala b/core/src/main/scala/org/apache/spark/network/nio/Connection.scala
index 1499da07bb..8d9ebadaf7 100644
--- a/core/src/main/scala/org/apache/spark/network/nio/Connection.scala
+++ b/core/src/main/scala/org/apache/spark/network/nio/Connection.scala
@@ -23,7 +23,7 @@ import java.nio.channels._
 import java.util.concurrent.ConcurrentLinkedQueue
 import java.util.LinkedList
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{ArrayBuffer, HashMap}
 import scala.util.control.NonFatal
 
@@ -145,7 +145,7 @@ abstract class Connection(val channel: SocketChannel, val selector: Selector,
   }
 
   def callOnExceptionCallbacks(e: Throwable) {
-    onExceptionCallbacks foreach {
+    onExceptionCallbacks.asScala.foreach {
       callback =>
         try {
           callback(this, e)
diff --git a/core/src/main/scala/org/apache/spark/partial/GroupedCountEvaluator.scala b/core/src/main/scala/org/apache/spark/partial/GroupedCountEvaluator.scala
index 91b07ce3af..5afce75680 100644
--- a/core/src/main/scala/org/apache/spark/partial/GroupedCountEvaluator.scala
+++ b/core/src/main/scala/org/apache/spark/partial/GroupedCountEvaluator.scala
@@ -19,7 +19,7 @@ package org.apache.spark.partial
 
 import java.util.{HashMap => JHashMap}
 
-import scala.collection.JavaConversions.mapAsScalaMap
+import scala.collection.JavaConverters._
 import scala.collection.Map
 import scala.collection.mutable.HashMap
 import scala.reflect.ClassTag
@@ -48,9 +48,9 @@ private[spark] class GroupedCountEvaluator[T : ClassTag](totalOutputs: Int, conf
     if (outputsMerged == totalOutputs) {
       val result = new JHashMap[T, BoundedDouble](sums.size)
       sums.foreach { case (key, sum) =>
-        result(key) = new BoundedDouble(sum, 1.0, sum, sum)
+        result.put(key, new BoundedDouble(sum, 1.0, sum, sum))
       }
-      result
+      result.asScala
     } else if (outputsMerged == 0) {
       new HashMap[T, BoundedDouble]
     } else {
@@ -64,9 +64,9 @@ private[spark] class GroupedCountEvaluator[T : ClassTag](totalOutputs: Int, conf
         val stdev = math.sqrt(variance)
         val low = mean - confFactor * stdev
         val high = mean + confFactor * stdev
-        result(key) = new BoundedDouble(mean, confidence, low, high)
+        result.put(key, new BoundedDouble(mean, confidence, low, high))
       }
-      result
+      result.asScala
     }
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/partial/GroupedMeanEvaluator.scala b/core/src/main/scala/org/apache/spark/partial/GroupedMeanEvaluator.scala
index af26c3d59a..a164040684 100644
--- a/core/src/main/scala/org/apache/spark/partial/GroupedMeanEvaluator.scala
+++ b/core/src/main/scala/org/apache/spark/partial/GroupedMeanEvaluator.scala
@@ -19,7 +19,7 @@ package org.apache.spark.partial
 
 import java.util.{HashMap => JHashMap}
 
-import scala.collection.JavaConversions.mapAsScalaMap
+import scala.collection.JavaConverters._
 import scala.collection.Map
 import scala.collection.mutable.HashMap
 
@@ -55,9 +55,9 @@ private[spark] class GroupedMeanEvaluator[T](totalOutputs: Int, confidence: Doub
       while (iter.hasNext) {
         val entry = iter.next()
         val mean = entry.getValue.mean
-        result(entry.getKey) = new BoundedDouble(mean, 1.0, mean, mean)
+        result.put(entry.getKey, new BoundedDouble(mean, 1.0, mean, mean))
       }
-      result
+      result.asScala
     } else if (outputsMerged == 0) {
       new HashMap[T, BoundedDouble]
     } else {
@@ -72,9 +72,9 @@ private[spark] class GroupedMeanEvaluator[T](totalOutputs: Int, confidence: Doub
         val confFactor = studentTCacher.get(counter.count)
         val low = mean - confFactor * stdev
         val high = mean + confFactor * stdev
-        result(entry.getKey) = new BoundedDouble(mean, confidence, low, high)
+        result.put(entry.getKey, new BoundedDouble(mean, confidence, low, high))
       }
-      result
+      result.asScala
     }
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/partial/GroupedSumEvaluator.scala b/core/src/main/scala/org/apache/spark/partial/GroupedSumEvaluator.scala
index 442fb86227..54a1beab35 100644
--- a/core/src/main/scala/org/apache/spark/partial/GroupedSumEvaluator.scala
+++ b/core/src/main/scala/org/apache/spark/partial/GroupedSumEvaluator.scala
@@ -19,7 +19,7 @@ package org.apache.spark.partial
 
 import java.util.{HashMap => JHashMap}
 
-import scala.collection.JavaConversions.mapAsScalaMap
+import scala.collection.JavaConverters._
 import scala.collection.Map
 import scala.collection.mutable.HashMap
 
@@ -55,9 +55,9 @@ private[spark] class GroupedSumEvaluator[T](totalOutputs: Int, confidence: Doubl
       while (iter.hasNext) {
         val entry = iter.next()
         val sum = entry.getValue.sum
-        result(entry.getKey) = new BoundedDouble(sum, 1.0, sum, sum)
+        result.put(entry.getKey, new BoundedDouble(sum, 1.0, sum, sum))
       }
-      result
+      result.asScala
     } else if (outputsMerged == 0) {
       new HashMap[T, BoundedDouble]
     } else {
@@ -80,9 +80,9 @@ private[spark] class GroupedSumEvaluator[T](totalOutputs: Int, confidence: Doubl
         val confFactor = studentTCacher.get(counter.count)
         val low = sumEstimate - confFactor * sumStdev
         val high = sumEstimate + confFactor * sumStdev
-        result(entry.getKey) = new BoundedDouble(sumEstimate, confidence, low, high)
+        result.put(entry.getKey, new BoundedDouble(sumEstimate, confidence, low, high))
       }
-      result
+      result.asScala
     }
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala b/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
index 326fafb230..4e5f2e8a5d 100644
--- a/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/PairRDDFunctions.scala
@@ -22,7 +22,7 @@ import java.text.SimpleDateFormat
 import java.util.{Date, HashMap => JHashMap}
 
 import scala.collection.{Map, mutable}
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 import scala.reflect.ClassTag
 import scala.util.DynamicVariable
@@ -312,14 +312,14 @@ class PairRDDFunctions[K, V](self: RDD[(K, V)])
     } : Iterator[JHashMap[K, V]]
 
     val mergeMaps = (m1: JHashMap[K, V], m2: JHashMap[K, V]) => {
-      m2.foreach { pair =>
+      m2.asScala.foreach { pair =>
         val old = m1.get(pair._1)
         m1.put(pair._1, if (old == null) pair._2 else cleanedF(old, pair._2))
       }
       m1
     } : JHashMap[K, V]
 
-    self.mapPartitions(reducePartition).reduce(mergeMaps)
+    self.mapPartitions(reducePartition).reduce(mergeMaps).asScala
   }
 
   /** Alias for reduceByKeyLocally */
diff --git a/core/src/main/scala/org/apache/spark/rdd/PipedRDD.scala b/core/src/main/scala/org/apache/spark/rdd/PipedRDD.scala
index 3bb9998e1d..afbe566b76 100644
--- a/core/src/main/scala/org/apache/spark/rdd/PipedRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/PipedRDD.scala
@@ -23,7 +23,7 @@ import java.io.IOException
 import java.io.PrintWriter
 import java.util.StringTokenizer
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.Map
 import scala.collection.mutable.ArrayBuffer
 import scala.io.Source
@@ -72,7 +72,7 @@ private[spark] class PipedRDD[T: ClassTag](
   }
 
   override def compute(split: Partition, context: TaskContext): Iterator[String] = {
-    val pb = new ProcessBuilder(command)
+    val pb = new ProcessBuilder(command.asJava)
     // Add the environmental variables to the process.
     val currentEnvVars = pb.environment()
     envVars.foreach { case (variable, value) => currentEnvVars.put(variable, value) }
@@ -81,7 +81,7 @@ private[spark] class PipedRDD[T: ClassTag](
     // so the user code can access the input filename
     if (split.isInstanceOf[HadoopPartition]) {
       val hadoopSplit = split.asInstanceOf[HadoopPartition]
-      currentEnvVars.putAll(hadoopSplit.getPipeEnvVars())
+      currentEnvVars.putAll(hadoopSplit.getPipeEnvVars().asJava)
     }
 
     // When spark.worker.separated.working.directory option is turned on, each
diff --git a/core/src/main/scala/org/apache/spark/rdd/SubtractedRDD.scala b/core/src/main/scala/org/apache/spark/rdd/SubtractedRDD.scala
index f7cb1791d4..9a4fa301b0 100644
--- a/core/src/main/scala/org/apache/spark/rdd/SubtractedRDD.scala
+++ b/core/src/main/scala/org/apache/spark/rdd/SubtractedRDD.scala
@@ -19,7 +19,7 @@ package org.apache.spark.rdd
 
 import java.util.{HashMap => JHashMap}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 import scala.reflect.ClassTag
 
@@ -125,7 +125,7 @@ private[spark] class SubtractedRDD[K: ClassTag, V: ClassTag, W: ClassTag](
     integrate(0, t => getSeq(t._1) += t._2)
     // the second dep is rdd2; remove all of its keys
     integrate(1, t => map.remove(t._1))
-    map.iterator.map { t => t._2.iterator.map { (t._1, _) } }.flatten
+    map.asScala.iterator.map(t => t._2.iterator.map((t._1, _))).flatten
   }
 
   override def clearDependencies() {
diff --git a/core/src/main/scala/org/apache/spark/scheduler/InputFormatInfo.scala b/core/src/main/scala/org/apache/spark/scheduler/InputFormatInfo.scala
index bac37bfdaa..0e438ab436 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/InputFormatInfo.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/InputFormatInfo.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.scheduler
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.immutable.Set
 import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet}
 
@@ -107,7 +107,7 @@ class InputFormatInfo(val configuration: Configuration, val inputFormatClazz: Cl
 
     val retval = new ArrayBuffer[SplitInfo]()
     val list = instance.getSplits(job)
-    for (split <- list) {
+    for (split <- list.asScala) {
       retval ++= SplitInfo.toSplitInfo(inputFormatClazz, path, split)
     }
 
diff --git a/core/src/main/scala/org/apache/spark/scheduler/Pool.scala b/core/src/main/scala/org/apache/spark/scheduler/Pool.scala
index 174b73221a..5821afea98 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/Pool.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/Pool.scala
@@ -19,7 +19,7 @@ package org.apache.spark.scheduler
 
 import java.util.concurrent.{ConcurrentHashMap, ConcurrentLinkedQueue}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 
 import org.apache.spark.Logging
@@ -74,7 +74,7 @@ private[spark] class Pool(
     if (schedulableNameToSchedulable.containsKey(schedulableName)) {
       return schedulableNameToSchedulable.get(schedulableName)
     }
-    for (schedulable <- schedulableQueue) {
+    for (schedulable <- schedulableQueue.asScala) {
       val sched = schedulable.getSchedulableByName(schedulableName)
       if (sched != null) {
         return sched
@@ -84,12 +84,12 @@ private[spark] class Pool(
   }
 
   override def executorLost(executorId: String, host: String) {
-    schedulableQueue.foreach(_.executorLost(executorId, host))
+    schedulableQueue.asScala.foreach(_.executorLost(executorId, host))
   }
 
   override def checkSpeculatableTasks(): Boolean = {
     var shouldRevive = false
-    for (schedulable <- schedulableQueue) {
+    for (schedulable <- schedulableQueue.asScala) {
       shouldRevive |= schedulable.checkSpeculatableTasks()
     }
     shouldRevive
@@ -98,7 +98,7 @@ private[spark] class Pool(
   override def getSortedTaskSetQueue: ArrayBuffer[TaskSetManager] = {
     var sortedTaskSetQueue = new ArrayBuffer[TaskSetManager]
     val sortedSchedulableQueue =
-      schedulableQueue.toSeq.sortWith(taskSetSchedulingAlgorithm.comparator)
+      schedulableQueue.asScala.toSeq.sortWith(taskSetSchedulingAlgorithm.comparator)
     for (schedulable <- sortedSchedulableQueue) {
       sortedTaskSetQueue ++= schedulable.getSortedTaskSetQueue
     }
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala
index d6e1e9e5be..452c32d541 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/CoarseMesosSchedulerBackend.scala
@@ -21,7 +21,7 @@ import java.io.File
 import java.util.concurrent.locks.ReentrantLock
 import java.util.{Collections, List => JList}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{HashMap, HashSet}
 
 import com.google.common.collect.HashBiMap
@@ -233,7 +233,7 @@ private[spark] class CoarseMesosSchedulerBackend(
   override def resourceOffers(d: SchedulerDriver, offers: JList[Offer]) {
     stateLock.synchronized {
       val filters = Filters.newBuilder().setRefuseSeconds(5).build()
-      for (offer <- offers) {
+      for (offer <- offers.asScala) {
         val offerAttributes = toAttributeMap(offer.getAttributesList)
         val meetsConstraints = matchesAttributeRequirements(slaveOfferConstraints, offerAttributes)
         val slaveId = offer.getSlaveId.getValue
@@ -251,21 +251,21 @@ private[spark] class CoarseMesosSchedulerBackend(
           val cpusToUse = math.min(cpus, maxCores - totalCoresAcquired)
           totalCoresAcquired += cpusToUse
           val taskId = newMesosTaskId()
-          taskIdToSlaveId(taskId) = slaveId
+          taskIdToSlaveId.put(taskId, slaveId)
           slaveIdsWithExecutors += slaveId
           coresByTaskId(taskId) = cpusToUse
           // Gather cpu resources from the available resources and use them in the task.
           val (remainingResources, cpuResourcesToUse) =
             partitionResources(offer.getResourcesList, "cpus", cpusToUse)
           val (_, memResourcesToUse) =
-            partitionResources(remainingResources, "mem", calculateTotalMemory(sc))
+            partitionResources(remainingResources.asJava, "mem", calculateTotalMemory(sc))
           val taskBuilder = MesosTaskInfo.newBuilder()
             .setTaskId(TaskID.newBuilder().setValue(taskId.toString).build())
             .setSlaveId(offer.getSlaveId)
             .setCommand(createCommand(offer, cpusToUse + extraCoresPerSlave, taskId))
             .setName("Task " + taskId)
-            .addAllResources(cpuResourcesToUse)
-            .addAllResources(memResourcesToUse)
+            .addAllResources(cpuResourcesToUse.asJava)
+            .addAllResources(memResourcesToUse.asJava)
 
           sc.conf.getOption("spark.mesos.executor.docker.image").foreach { image =>
             MesosSchedulerBackendUtil
@@ -314,9 +314,9 @@ private[spark] class CoarseMesosSchedulerBackend(
       }
 
       if (TaskState.isFinished(TaskState.fromMesos(state))) {
-        val slaveId = taskIdToSlaveId(taskId)
+        val slaveId = taskIdToSlaveId.get(taskId)
         slaveIdsWithExecutors -= slaveId
-        taskIdToSlaveId -= taskId
+        taskIdToSlaveId.remove(taskId)
         // Remove the cores we have remembered for this task, if it's in the hashmap
         for (cores <- coresByTaskId.get(taskId)) {
           totalCoresAcquired -= cores
@@ -361,7 +361,7 @@ private[spark] class CoarseMesosSchedulerBackend(
     stateLock.synchronized {
       if (slaveIdsWithExecutors.contains(slaveId)) {
         val slaveIdToTaskId = taskIdToSlaveId.inverse()
-        if (slaveIdToTaskId.contains(slaveId)) {
+        if (slaveIdToTaskId.containsKey(slaveId)) {
           val taskId: Int = slaveIdToTaskId.get(slaveId)
           taskIdToSlaveId.remove(taskId)
           removeExecutor(sparkExecutorId(slaveId, taskId.toString), reason)
@@ -411,7 +411,7 @@ private[spark] class CoarseMesosSchedulerBackend(
     val slaveIdToTaskId = taskIdToSlaveId.inverse()
     for (executorId <- executorIds) {
       val slaveId = executorId.split("/")(0)
-      if (slaveIdToTaskId.contains(slaveId)) {
+      if (slaveIdToTaskId.containsKey(slaveId)) {
         mesosDriver.killTask(
           TaskID.newBuilder().setValue(slaveIdToTaskId.get(slaveId).toString).build())
         pendingRemovedSlaveIds += slaveId
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterPersistenceEngine.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterPersistenceEngine.scala
index 3efc536f14..e0c547dce6 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterPersistenceEngine.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterPersistenceEngine.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.scheduler.cluster.mesos
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.curator.framework.CuratorFramework
 import org.apache.zookeeper.CreateMode
@@ -129,6 +129,6 @@ private[spark] class ZookeeperMesosClusterPersistenceEngine(
   }
 
   override def fetchAll[T](): Iterable[T] = {
-    zk.getChildren.forPath(WORKING_DIR).map(fetch[T]).flatten
+    zk.getChildren.forPath(WORKING_DIR).asScala.flatMap(fetch[T])
   }
 }
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterScheduler.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterScheduler.scala
index 1206f184fb..07da9242b9 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterScheduler.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosClusterScheduler.scala
@@ -21,7 +21,7 @@ import java.io.File
 import java.util.concurrent.locks.ReentrantLock
 import java.util.{Collections, Date, List => JList}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
 
@@ -350,7 +350,7 @@ private[spark] class MesosClusterScheduler(
         }
         // TODO: Page the status updates to avoid trying to reconcile
         // a large amount of tasks at once.
-        driver.reconcileTasks(statuses)
+        driver.reconcileTasks(statuses.toSeq.asJava)
       }
     }
   }
@@ -493,10 +493,10 @@ private[spark] class MesosClusterScheduler(
   }
 
   override def resourceOffers(driver: SchedulerDriver, offers: JList[Offer]): Unit = {
-    val currentOffers = offers.map { o =>
+    val currentOffers = offers.asScala.map(o =>
       new ResourceOffer(
         o, getResource(o.getResourcesList, "cpus"), getResource(o.getResourcesList, "mem"))
-    }.toList
+    ).toList
     logTrace(s"Received offers from Mesos: \n${currentOffers.mkString("\n")}")
     val tasks = new mutable.HashMap[OfferID, ArrayBuffer[TaskInfo]]()
     val currentTime = new Date()
@@ -521,10 +521,10 @@ private[spark] class MesosClusterScheduler(
         currentOffers,
         tasks)
     }
-    tasks.foreach { case (offerId, tasks) =>
-      driver.launchTasks(Collections.singleton(offerId), tasks)
+    tasks.foreach { case (offerId, taskInfos) =>
+      driver.launchTasks(Collections.singleton(offerId), taskInfos.asJava)
     }
-    offers
+    offers.asScala
       .filter(o => !tasks.keySet.contains(o.getId))
       .foreach(o => driver.declineOffer(o.getId))
   }
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala
index 5c20606d58..2e424054be 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackend.scala
@@ -20,7 +20,7 @@ package org.apache.spark.scheduler.cluster.mesos
 import java.io.File
 import java.util.{ArrayList => JArrayList, Collections, List => JList}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{HashMap, HashSet}
 
 import org.apache.mesos.{Scheduler => MScheduler, _}
@@ -129,14 +129,12 @@ private[spark] class MesosSchedulerBackend(
     val (resourcesAfterCpu, usedCpuResources) =
       partitionResources(availableResources, "cpus", scheduler.CPUS_PER_TASK)
     val (resourcesAfterMem, usedMemResources) =
-      partitionResources(resourcesAfterCpu, "mem", calculateTotalMemory(sc))
+      partitionResources(resourcesAfterCpu.asJava, "mem", calculateTotalMemory(sc))
 
-    builder.addAllResources(usedCpuResources)
-    builder.addAllResources(usedMemResources)
+    builder.addAllResources(usedCpuResources.asJava)
+    builder.addAllResources(usedMemResources.asJava)
 
-    sc.conf.getOption("spark.mesos.uris").map { uris =>
-      setupUris(uris, command)
-    }
+    sc.conf.getOption("spark.mesos.uris").foreach(setupUris(_, command))
 
     val executorInfo = builder
       .setExecutorId(ExecutorID.newBuilder().setValue(execId).build())
@@ -148,7 +146,7 @@ private[spark] class MesosSchedulerBackend(
         .setupContainerBuilderDockerInfo(image, sc.conf, executorInfo.getContainerBuilder())
     }
 
-    (executorInfo.build(), resourcesAfterMem)
+    (executorInfo.build(), resourcesAfterMem.asJava)
   }
 
   /**
@@ -193,7 +191,7 @@ private[spark] class MesosSchedulerBackend(
 
   private def getTasksSummary(tasks: JArrayList[MesosTaskInfo]): String = {
     val builder = new StringBuilder
-    tasks.foreach { t =>
+    tasks.asScala.foreach { t =>
       builder.append("Task id: ").append(t.getTaskId.getValue).append("\n")
         .append("Slave id: ").append(t.getSlaveId.getValue).append("\n")
         .append("Task resources: ").append(t.getResourcesList).append("\n")
@@ -211,7 +209,7 @@ private[spark] class MesosSchedulerBackend(
   override def resourceOffers(d: SchedulerDriver, offers: JList[Offer]) {
     inClassLoader() {
       // Fail-fast on offers we know will be rejected
-      val (usableOffers, unUsableOffers) = offers.partition { o =>
+      val (usableOffers, unUsableOffers) = offers.asScala.partition { o =>
         val mem = getResource(o.getResourcesList, "mem")
         val cpus = getResource(o.getResourcesList, "cpus")
         val slaveId = o.getSlaveId.getValue
@@ -323,10 +321,10 @@ private[spark] class MesosSchedulerBackend(
       .setSlaveId(SlaveID.newBuilder().setValue(slaveId).build())
       .setExecutor(executorInfo)
       .setName(task.name)
-      .addAllResources(cpuResources)
+      .addAllResources(cpuResources.asJava)
       .setData(MesosTaskLaunchData(task.serializedTask, task.attemptNumber).toByteString)
       .build()
-    (taskInfo, finalResources)
+    (taskInfo, finalResources.asJava)
   }
 
   override def statusUpdate(d: SchedulerDriver, status: TaskStatus) {
diff --git a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala
index 5b854aa5c2..860c8e097b 100644
--- a/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala
+++ b/core/src/main/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerUtils.scala
@@ -20,7 +20,7 @@ package org.apache.spark.scheduler.cluster.mesos
 import java.util.{List => JList}
 import java.util.concurrent.CountDownLatch
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 import scala.util.control.NonFatal
 
@@ -137,7 +137,7 @@ private[mesos] trait MesosSchedulerUtils extends Logging {
   protected def getResource(res: JList[Resource], name: String): Double = {
     // A resource can have multiple values in the offer since it can either be from
     // a specific role or wildcard.
-    res.filter(_.getName == name).map(_.getScalar.getValue).sum
+    res.asScala.filter(_.getName == name).map(_.getScalar.getValue).sum
   }
 
   protected def markRegistered(): Unit = {
@@ -169,7 +169,7 @@ private[mesos] trait MesosSchedulerUtils extends Logging {
       amountToUse: Double): (List[Resource], List[Resource]) = {
     var remain = amountToUse
     var requestedResources = new ArrayBuffer[Resource]
-    val remainingResources = resources.map {
+    val remainingResources = resources.asScala.map {
       case r => {
         if (remain > 0 &&
           r.getType == Value.Type.SCALAR &&
@@ -214,7 +214,7 @@ private[mesos] trait MesosSchedulerUtils extends Logging {
    * @return
    */
   protected def toAttributeMap(offerAttributes: JList[Attribute]): Map[String, GeneratedMessage] = {
-    offerAttributes.map(attr => {
+    offerAttributes.asScala.map(attr => {
       val attrValue = attr.getType match {
         case Value.Type.SCALAR => attr.getScalar
         case Value.Type.RANGES => attr.getRanges
@@ -253,7 +253,7 @@ private[mesos] trait MesosSchedulerUtils extends Logging {
             requiredValues.map(_.toLong).exists(offerRange.contains(_))
           case Some(offeredValue: Value.Set) =>
             // check if the specified required values is a subset of offered set
-            requiredValues.subsetOf(offeredValue.getItemList.toSet)
+            requiredValues.subsetOf(offeredValue.getItemList.asScala.toSet)
           case Some(textValue: Value.Text) =>
             // check if the specified value is equal, if multiple values are specified
             // we succeed if any of them match.
@@ -299,14 +299,13 @@ private[mesos] trait MesosSchedulerUtils extends Logging {
       Map()
     } else {
       try {
-        Map() ++ mapAsScalaMap(splitter.split(constraintsVal)).map {
-          case (k, v) =>
-            if (v == null || v.isEmpty) {
-              (k, Set[String]())
-            } else {
-              (k, v.split(',').toSet)
-            }
-        }
+        splitter.split(constraintsVal).asScala.toMap.mapValues(v =>
+          if (v == null || v.isEmpty) {
+            Set[String]()
+          } else {
+            v.split(',').toSet
+          }
+        )
       } catch {
         case NonFatal(e) =>
           throw new IllegalArgumentException(s"Bad constraint string: $constraintsVal", e)
diff --git a/core/src/main/scala/org/apache/spark/serializer/KryoSerializer.scala b/core/src/main/scala/org/apache/spark/serializer/KryoSerializer.scala
index 0ff7562e91..048a938507 100644
--- a/core/src/main/scala/org/apache/spark/serializer/KryoSerializer.scala
+++ b/core/src/main/scala/org/apache/spark/serializer/KryoSerializer.scala
@@ -21,6 +21,7 @@ import java.io.{EOFException, IOException, InputStream, OutputStream}
 import java.nio.ByteBuffer
 import javax.annotation.Nullable
 
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
 import com.esotericsoftware.kryo.{Kryo, KryoException}
@@ -373,16 +374,15 @@ private class JavaIterableWrapperSerializer
   override def read(kryo: Kryo, in: KryoInput, clz: Class[java.lang.Iterable[_]])
     : java.lang.Iterable[_] = {
     kryo.readClassAndObject(in) match {
-      case scalaIterable: Iterable[_] =>
-        scala.collection.JavaConversions.asJavaIterable(scalaIterable)
-      case javaIterable: java.lang.Iterable[_] =>
-        javaIterable
+      case scalaIterable: Iterable[_] => scalaIterable.asJava
+      case javaIterable: java.lang.Iterable[_] => javaIterable
     }
   }
 }
 
 private object JavaIterableWrapperSerializer extends Logging {
-  // The class returned by asJavaIterable (scala.collection.convert.Wrappers$IterableWrapper).
+  // The class returned by JavaConverters.asJava
+  // (scala.collection.convert.Wrappers$IterableWrapper).
   val wrapperClass =
     scala.collection.convert.WrapAsJava.asJavaIterable(Seq(1)).getClass
 
diff --git a/core/src/main/scala/org/apache/spark/shuffle/FileShuffleBlockResolver.scala b/core/src/main/scala/org/apache/spark/shuffle/FileShuffleBlockResolver.scala
index f6a96d81e7..c057de9b3f 100644
--- a/core/src/main/scala/org/apache/spark/shuffle/FileShuffleBlockResolver.scala
+++ b/core/src/main/scala/org/apache/spark/shuffle/FileShuffleBlockResolver.scala
@@ -21,7 +21,7 @@ import java.io.File
 import java.util.concurrent.ConcurrentLinkedQueue
 import java.util.concurrent.atomic.AtomicInteger
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.{Logging, SparkConf, SparkEnv}
 import org.apache.spark.executor.ShuffleWriteMetrics
@@ -210,11 +210,13 @@ private[spark] class FileShuffleBlockResolver(conf: SparkConf)
     shuffleStates.get(shuffleId) match {
       case Some(state) =>
         if (consolidateShuffleFiles) {
-          for (fileGroup <- state.allFileGroups; file <- fileGroup.files) {
+          for (fileGroup <- state.allFileGroups.asScala;
+               file <- fileGroup.files) {
             file.delete()
           }
         } else {
-          for (mapId <- state.completedMapTasks; reduceId <- 0 until state.numBuckets) {
+          for (mapId <- state.completedMapTasks.asScala;
+               reduceId <- 0 until state.numBuckets) {
             val blockId = new ShuffleBlockId(shuffleId, mapId, reduceId)
             blockManager.diskBlockManager.getFile(blockId).delete()
           }
diff --git a/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala b/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala
index 6fec524070..7db6035553 100644
--- a/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala
+++ b/core/src/main/scala/org/apache/spark/storage/BlockManagerMasterEndpoint.scala
@@ -21,7 +21,7 @@ import java.util.{HashMap => JHashMap}
 
 import scala.collection.immutable.HashSet
 import scala.collection.mutable
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.concurrent.{ExecutionContext, Future}
 
 import org.apache.spark.rpc.{RpcEndpointRef, RpcEnv, RpcCallContext, ThreadSafeRpcEndpoint}
@@ -133,7 +133,7 @@ class BlockManagerMasterEndpoint(
 
     // Find all blocks for the given RDD, remove the block from both blockLocations and
     // the blockManagerInfo that is tracking the blocks.
-    val blocks = blockLocations.keys.flatMap(_.asRDDId).filter(_.rddId == rddId)
+    val blocks = blockLocations.asScala.keys.flatMap(_.asRDDId).filter(_.rddId == rddId)
     blocks.foreach { blockId =>
       val bms: mutable.HashSet[BlockManagerId] = blockLocations.get(blockId)
       bms.foreach(bm => blockManagerInfo.get(bm).foreach(_.removeBlock(blockId)))
@@ -242,7 +242,7 @@ class BlockManagerMasterEndpoint(
 
   private def storageStatus: Array[StorageStatus] = {
     blockManagerInfo.map { case (blockManagerId, info) =>
-      new StorageStatus(blockManagerId, info.maxMem, info.blocks)
+      new StorageStatus(blockManagerId, info.maxMem, info.blocks.asScala)
     }.toArray
   }
 
@@ -292,7 +292,7 @@ class BlockManagerMasterEndpoint(
           if (askSlaves) {
             info.slaveEndpoint.ask[Seq[BlockId]](getMatchingBlockIds)
           } else {
-            Future { info.blocks.keys.filter(filter).toSeq }
+            Future { info.blocks.asScala.keys.filter(filter).toSeq }
           }
         future
       }
diff --git a/core/src/main/scala/org/apache/spark/util/AkkaUtils.scala b/core/src/main/scala/org/apache/spark/util/AkkaUtils.scala
index 78e7ddc27d..1738258a0c 100644
--- a/core/src/main/scala/org/apache/spark/util/AkkaUtils.scala
+++ b/core/src/main/scala/org/apache/spark/util/AkkaUtils.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.util
 
-import scala.collection.JavaConversions.mapAsJavaMap
+import scala.collection.JavaConverters._
 
 import akka.actor.{ActorRef, ActorSystem, ExtendedActorSystem}
 import akka.pattern.ask
@@ -92,7 +92,7 @@ private[spark] object AkkaUtils extends Logging {
     val akkaSslConfig = securityManager.akkaSSLOptions.createAkkaConfig
         .getOrElse(ConfigFactory.empty())
 
-    val akkaConf = ConfigFactory.parseMap(conf.getAkkaConf.toMap[String, String])
+    val akkaConf = ConfigFactory.parseMap(conf.getAkkaConf.toMap.asJava)
       .withFallback(akkaSslConfig).withFallback(ConfigFactory.parseString(
       s"""
       |akka.daemonic = on
diff --git a/core/src/main/scala/org/apache/spark/util/ListenerBus.scala b/core/src/main/scala/org/apache/spark/util/ListenerBus.scala
index a725767d08..13cb516b58 100644
--- a/core/src/main/scala/org/apache/spark/util/ListenerBus.scala
+++ b/core/src/main/scala/org/apache/spark/util/ListenerBus.scala
@@ -19,12 +19,11 @@ package org.apache.spark.util
 
 import java.util.concurrent.CopyOnWriteArrayList
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 import scala.util.control.NonFatal
 
 import org.apache.spark.Logging
-import org.apache.spark.scheduler.SparkListener
 
 /**
  * An event bus which posts events to its listeners.
@@ -46,7 +45,7 @@ private[spark] trait ListenerBus[L <: AnyRef, E] extends Logging {
    * `postToAll` in the same thread for all events.
    */
   final def postToAll(event: E): Unit = {
-    // JavaConversions will create a JIterableWrapper if we use some Scala collection functions.
+    // JavaConverters can create a JIterableWrapper if we use asScala.
     // However, this method will be called frequently. To avoid the wrapper cost, here ewe use
     // Java Iterator directly.
     val iter = listeners.iterator
@@ -69,7 +68,7 @@ private[spark] trait ListenerBus[L <: AnyRef, E] extends Logging {
 
   private[spark] def findListenersByClass[T <: L : ClassTag](): Seq[T] = {
     val c = implicitly[ClassTag[T]].runtimeClass
-    listeners.filter(_.getClass == c).map(_.asInstanceOf[T]).toSeq
+    listeners.asScala.filter(_.getClass == c).map(_.asInstanceOf[T]).toSeq
   }
 
 }
diff --git a/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala b/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala
index 169489df6c..a1c33212cd 100644
--- a/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala
+++ b/core/src/main/scala/org/apache/spark/util/MutableURLClassLoader.scala
@@ -21,8 +21,6 @@ import java.net.{URLClassLoader, URL}
 import java.util.Enumeration
 import java.util.concurrent.ConcurrentHashMap
 
-import scala.collection.JavaConversions._
-
 /**
  * URL class loader that exposes the `addURL` and `getURLs` methods in URLClassLoader.
  */
diff --git a/core/src/main/scala/org/apache/spark/util/TimeStampedHashMap.scala b/core/src/main/scala/org/apache/spark/util/TimeStampedHashMap.scala
index 8de75ba9a9..d7e5143c30 100644
--- a/core/src/main/scala/org/apache/spark/util/TimeStampedHashMap.scala
+++ b/core/src/main/scala/org/apache/spark/util/TimeStampedHashMap.scala
@@ -21,7 +21,8 @@ import java.util.Set
 import java.util.Map.Entry
 import java.util.concurrent.ConcurrentHashMap
 
-import scala.collection.{JavaConversions, mutable}
+import scala.collection.JavaConverters._
+import scala.collection.mutable
 
 import org.apache.spark.Logging
 
@@ -50,8 +51,7 @@ private[spark] class TimeStampedHashMap[A, B](updateTimeStampOnGet: Boolean = fa
   }
 
   def iterator: Iterator[(A, B)] = {
-    val jIterator = getEntrySet.iterator
-    JavaConversions.asScalaIterator(jIterator).map(kv => (kv.getKey, kv.getValue.value))
+    getEntrySet.iterator.asScala.map(kv => (kv.getKey, kv.getValue.value))
   }
 
   def getEntrySet: Set[Entry[A, TimeStampedValue[B]]] = internalMap.entrySet
@@ -90,9 +90,7 @@ private[spark] class TimeStampedHashMap[A, B](updateTimeStampOnGet: Boolean = fa
   }
 
   override def filter(p: ((A, B)) => Boolean): mutable.Map[A, B] = {
-    JavaConversions.mapAsScalaConcurrentMap(internalMap)
-      .map { case (k, TimeStampedValue(v, t)) => (k, v) }
-      .filter(p)
+    internalMap.asScala.map { case (k, TimeStampedValue(v, t)) => (k, v) }.filter(p)
   }
 
   override def empty: mutable.Map[A, B] = new TimeStampedHashMap[A, B]()
diff --git a/core/src/main/scala/org/apache/spark/util/TimeStampedHashSet.scala b/core/src/main/scala/org/apache/spark/util/TimeStampedHashSet.scala
index 7cd8f28b12..65efeb1f4c 100644
--- a/core/src/main/scala/org/apache/spark/util/TimeStampedHashSet.scala
+++ b/core/src/main/scala/org/apache/spark/util/TimeStampedHashSet.scala
@@ -19,7 +19,7 @@ package org.apache.spark.util
 
 import java.util.concurrent.ConcurrentHashMap
 
-import scala.collection.JavaConversions
+import scala.collection.JavaConverters._
 import scala.collection.mutable.Set
 
 private[spark] class TimeStampedHashSet[A] extends Set[A] {
@@ -31,7 +31,7 @@ private[spark] class TimeStampedHashSet[A] extends Set[A] {
 
   def iterator: Iterator[A] = {
     val jIterator = internalMap.entrySet().iterator()
-    JavaConversions.asScalaIterator(jIterator).map(_.getKey)
+    jIterator.asScala.map(_.getKey)
   }
 
   override def + (elem: A): Set[A] = {
diff --git a/core/src/main/scala/org/apache/spark/util/Utils.scala b/core/src/main/scala/org/apache/spark/util/Utils.scala
index 8313312226..2bab4af2e7 100644
--- a/core/src/main/scala/org/apache/spark/util/Utils.scala
+++ b/core/src/main/scala/org/apache/spark/util/Utils.scala
@@ -25,7 +25,7 @@ import java.util.{Properties, Locale, Random, UUID}
 import java.util.concurrent._
 import javax.net.ssl.HttpsURLConnection
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.Map
 import scala.collection.mutable.ArrayBuffer
 import scala.io.Source
@@ -748,12 +748,12 @@ private[spark] object Utils extends Logging {
         // getNetworkInterfaces returns ifs in reverse order compared to ifconfig output order
         // on unix-like system. On windows, it returns in index order.
         // It's more proper to pick ip address following system output order.
-        val activeNetworkIFs = NetworkInterface.getNetworkInterfaces.toList
+        val activeNetworkIFs = NetworkInterface.getNetworkInterfaces.asScala.toSeq
         val reOrderedNetworkIFs = if (isWindows) activeNetworkIFs else activeNetworkIFs.reverse
 
         for (ni <- reOrderedNetworkIFs) {
-          val addresses = ni.getInetAddresses.toList
-            .filterNot(addr => addr.isLinkLocalAddress || addr.isLoopbackAddress)
+          val addresses = ni.getInetAddresses.asScala
+            .filterNot(addr => addr.isLinkLocalAddress || addr.isLoopbackAddress).toSeq
           if (addresses.nonEmpty) {
             val addr = addresses.find(_.isInstanceOf[Inet4Address]).getOrElse(addresses.head)
             // because of Inet6Address.toHostName may add interface at the end if it knows about it
@@ -1498,10 +1498,8 @@ private[spark] object Utils extends Logging {
     * properties which have been set explicitly, as well as those for which only a default value
     * has been defined. */
   def getSystemProperties: Map[String, String] = {
-    val sysProps = for (key <- System.getProperties.stringPropertyNames()) yield
-      (key, System.getProperty(key))
-
-    sysProps.toMap
+    System.getProperties.stringPropertyNames().asScala
+      .map(key => (key, System.getProperty(key))).toMap
   }
 
   /**
@@ -1812,7 +1810,8 @@ private[spark] object Utils extends Logging {
     try {
       val properties = new Properties()
       properties.load(inReader)
-      properties.stringPropertyNames().map(k => (k, properties(k).trim)).toMap
+      properties.stringPropertyNames().asScala.map(
+        k => (k, properties.getProperty(k).trim)).toMap
     } catch {
       case e: IOException =>
         throw new SparkException(s"Failed when loading Spark properties from $filename", e)
@@ -1941,7 +1940,8 @@ private[spark] object Utils extends Logging {
           return true
         }
         isBindCollision(e.getCause)
-      case e: MultiException => e.getThrowables.exists(isBindCollision)
+      case e: MultiException =>
+        e.getThrowables.asScala.exists(isBindCollision)
       case e: Exception => isBindCollision(e.getCause)
       case _ => false
     }
diff --git a/core/src/main/scala/org/apache/spark/util/collection/Utils.scala b/core/src/main/scala/org/apache/spark/util/collection/Utils.scala
index bdbca00a00..4939b600db 100644
--- a/core/src/main/scala/org/apache/spark/util/collection/Utils.scala
+++ b/core/src/main/scala/org/apache/spark/util/collection/Utils.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.util.collection
 
-import scala.collection.JavaConversions.{collectionAsScalaIterable, asJavaIterator}
+import scala.collection.JavaConverters._
 
 import com.google.common.collect.{Ordering => GuavaOrdering}
 
@@ -34,6 +34,6 @@ private[spark] object Utils {
     val ordering = new GuavaOrdering[T] {
       override def compare(l: T, r: T): Int = ord.compare(l, r)
     }
-    collectionAsScalaIterable(ordering.leastOf(asJavaIterator(input), num)).iterator
+    ordering.leastOf(input.asJava, num).iterator.asScala
   }
 }
diff --git a/core/src/test/java/org/apache/spark/JavaAPISuite.java b/core/src/test/java/org/apache/spark/JavaAPISuite.java
index ffe4b4baff..ebd3d61ae7 100644
--- a/core/src/test/java/org/apache/spark/JavaAPISuite.java
+++ b/core/src/test/java/org/apache/spark/JavaAPISuite.java
@@ -24,10 +24,10 @@ import java.net.URI;
 import java.util.*;
 import java.util.concurrent.*;
 
-import scala.collection.JavaConversions;
 import scala.Tuple2;
 import scala.Tuple3;
 import scala.Tuple4;
+import scala.collection.JavaConverters;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.Iterables;
@@ -1473,7 +1473,9 @@ public class JavaAPISuite implements Serializable {
     Assert.assertEquals(expected, results);
 
     Partitioner defaultPartitioner = Partitioner.defaultPartitioner(
-        combinedRDD.rdd(), JavaConversions.asScalaBuffer(Lists.<RDD<?>>newArrayList()));
+        combinedRDD.rdd(),
+        JavaConverters.collectionAsScalaIterableConverter(
+            Collections.<RDD<?>>emptyList()).asScala().toSeq());
     combinedRDD = originalRDD.keyBy(keyFunction)
         .combineByKey(
              createCombinerFunction,
diff --git a/core/src/test/scala/org/apache/spark/SparkConfSuite.scala b/core/src/test/scala/org/apache/spark/SparkConfSuite.scala
index 90cb7da94e..ff9a92cc0a 100644
--- a/core/src/test/scala/org/apache/spark/SparkConfSuite.scala
+++ b/core/src/test/scala/org/apache/spark/SparkConfSuite.scala
@@ -19,6 +19,7 @@ package org.apache.spark
 
 import java.util.concurrent.{TimeUnit, Executors}
 
+import scala.collection.JavaConverters._
 import scala.concurrent.duration._
 import scala.language.postfixOps
 import scala.util.{Try, Random}
@@ -148,7 +149,6 @@ class SparkConfSuite extends SparkFunSuite with LocalSparkContext with ResetSyst
   }
 
   test("Thread safeness - SPARK-5425") {
-    import scala.collection.JavaConversions._
     val executor = Executors.newSingleThreadScheduledExecutor()
     val sf = executor.scheduleAtFixedRate(new Runnable {
       override def run(): Unit =
@@ -163,8 +163,9 @@ class SparkConfSuite extends SparkFunSuite with LocalSparkContext with ResetSyst
       }
     } finally {
       executor.shutdownNow()
-      for (key <- System.getProperties.stringPropertyNames() if key.startsWith("spark.5425."))
-        System.getProperties.remove(key)
+      val sysProps = System.getProperties
+      for (key <- sysProps.stringPropertyNames().asScala if key.startsWith("spark.5425."))
+        sysProps.remove(key)
     }
   }
 
diff --git a/core/src/test/scala/org/apache/spark/deploy/LogUrlsStandaloneSuite.scala b/core/src/test/scala/org/apache/spark/deploy/LogUrlsStandaloneSuite.scala
index cbd2aee10c..86eb41dd7e 100644
--- a/core/src/test/scala/org/apache/spark/deploy/LogUrlsStandaloneSuite.scala
+++ b/core/src/test/scala/org/apache/spark/deploy/LogUrlsStandaloneSuite.scala
@@ -19,7 +19,6 @@ package org.apache.spark.deploy
 
 import java.net.URL
 
-import scala.collection.JavaConversions._
 import scala.collection.mutable
 import scala.io.Source
 
diff --git a/core/src/test/scala/org/apache/spark/deploy/RPackageUtilsSuite.scala b/core/src/test/scala/org/apache/spark/deploy/RPackageUtilsSuite.scala
index 47a64081e2..1ed4bae3ca 100644
--- a/core/src/test/scala/org/apache/spark/deploy/RPackageUtilsSuite.scala
+++ b/core/src/test/scala/org/apache/spark/deploy/RPackageUtilsSuite.scala
@@ -21,14 +21,14 @@ import java.io.{PrintStream, OutputStream, File}
 import java.net.URI
 import java.util.jar.Attributes.Name
 import java.util.jar.{JarFile, Manifest}
-import java.util.zip.{ZipEntry, ZipFile}
+import java.util.zip.ZipFile
 
-import org.scalatest.BeforeAndAfterEach
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 
 import com.google.common.io.Files
 import org.apache.commons.io.FileUtils
+import org.scalatest.BeforeAndAfterEach
 
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.api.r.RUtils
@@ -142,7 +142,7 @@ class RPackageUtilsSuite extends SparkFunSuite with BeforeAndAfterEach {
       IvyTestUtils.writeFile(fakePackageDir, "DESCRIPTION", "abc")
       val finalZip = RPackageUtils.zipRLibraries(tempDir, "sparkr.zip")
       assert(finalZip.exists())
-      val entries = new ZipFile(finalZip).entries().toSeq.map(_.getName)
+      val entries = new ZipFile(finalZip).entries().asScala.map(_.getName).toSeq
       assert(entries.contains("/test.R"))
       assert(entries.contains("/SparkR/abc.R"))
       assert(entries.contains("/SparkR/DESCRIPTION"))
diff --git a/core/src/test/scala/org/apache/spark/deploy/worker/ExecutorRunnerTest.scala b/core/src/test/scala/org/apache/spark/deploy/worker/ExecutorRunnerTest.scala
index bed6f3ea61..98664dc110 100644
--- a/core/src/test/scala/org/apache/spark/deploy/worker/ExecutorRunnerTest.scala
+++ b/core/src/test/scala/org/apache/spark/deploy/worker/ExecutorRunnerTest.scala
@@ -19,8 +19,6 @@ package org.apache.spark.deploy.worker
 
 import java.io.File
 
-import scala.collection.JavaConversions._
-
 import org.apache.spark.deploy.{ApplicationDescription, Command, ExecutorState}
 import org.apache.spark.{SecurityManager, SparkConf, SparkFunSuite}
 
@@ -36,6 +34,7 @@ class ExecutorRunnerTest extends SparkFunSuite {
       ExecutorState.RUNNING)
     val builder = CommandUtils.buildProcessBuilder(
       appDesc.command, new SecurityManager(conf), 512, sparkHome, er.substituteVariables)
-    assert(builder.command().last === appId)
+    val builderCommand = builder.command()
+    assert(builderCommand.get(builderCommand.size() - 1) === appId)
   }
 }
diff --git a/core/src/test/scala/org/apache/spark/scheduler/SparkListenerSuite.scala b/core/src/test/scala/org/apache/spark/scheduler/SparkListenerSuite.scala
index 730535ece7..a9652d7e7d 100644
--- a/core/src/test/scala/org/apache/spark/scheduler/SparkListenerSuite.scala
+++ b/core/src/test/scala/org/apache/spark/scheduler/SparkListenerSuite.scala
@@ -20,7 +20,7 @@ package org.apache.spark.scheduler
 import java.util.concurrent.Semaphore
 
 import scala.collection.mutable
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.scalatest.Matchers
 
@@ -365,10 +365,9 @@ class SparkListenerSuite extends SparkFunSuite with LocalSparkContext with Match
       .set("spark.extraListeners", classOf[ListenerThatAcceptsSparkConf].getName + "," +
         classOf[BasicJobCounter].getName)
     sc = new SparkContext(conf)
-    sc.listenerBus.listeners.collect { case x: BasicJobCounter => x}.size should be (1)
-    sc.listenerBus.listeners.collect {
-      case x: ListenerThatAcceptsSparkConf => x
-    }.size should be (1)
+    sc.listenerBus.listeners.asScala.count(_.isInstanceOf[BasicJobCounter]) should be (1)
+    sc.listenerBus.listeners.asScala
+      .count(_.isInstanceOf[ListenerThatAcceptsSparkConf]) should be (1)
   }
 
   /**
diff --git a/core/src/test/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackendSuite.scala b/core/src/test/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackendSuite.scala
index 5ed30f64d7..319b3173e7 100644
--- a/core/src/test/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackendSuite.scala
+++ b/core/src/test/scala/org/apache/spark/scheduler/cluster/mesos/MesosSchedulerBackendSuite.scala
@@ -18,10 +18,11 @@
 package org.apache.spark.scheduler.cluster.mesos
 
 import java.nio.ByteBuffer
-import java.util
+import java.util.Arrays
+import java.util.Collection
 import java.util.Collections
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
 
@@ -61,7 +62,7 @@ class MesosSchedulerBackendSuite extends SparkFunSuite with LocalSparkContext wi
 
     val mesosSchedulerBackend = new MesosSchedulerBackend(taskScheduler, sc, "master")
 
-    val resources = List(
+    val resources = Arrays.asList(
       mesosSchedulerBackend.createResource("cpus", 4),
       mesosSchedulerBackend.createResource("mem", 1024))
     // uri is null.
@@ -98,7 +99,7 @@ class MesosSchedulerBackendSuite extends SparkFunSuite with LocalSparkContext wi
     val backend = new MesosSchedulerBackend(taskScheduler, sc, "master")
 
     val (execInfo, _) = backend.createExecutorInfo(
-      List(backend.createResource("cpus", 4)), "mockExecutor")
+      Arrays.asList(backend.createResource("cpus", 4)), "mockExecutor")
     assert(execInfo.getContainer.getDocker.getImage.equals("spark/mock"))
     val portmaps = execInfo.getContainer.getDocker.getPortMappingsList
     assert(portmaps.get(0).getHostPort.equals(80))
@@ -179,7 +180,7 @@ class MesosSchedulerBackendSuite extends SparkFunSuite with LocalSparkContext wi
     when(taskScheduler.resourceOffers(expectedWorkerOffers)).thenReturn(Seq(Seq(taskDesc)))
     when(taskScheduler.CPUS_PER_TASK).thenReturn(2)
 
-    val capture = ArgumentCaptor.forClass(classOf[util.Collection[TaskInfo]])
+    val capture = ArgumentCaptor.forClass(classOf[Collection[TaskInfo]])
     when(
       driver.launchTasks(
         Matchers.eq(Collections.singleton(mesosOffers.get(0).getId)),
@@ -279,7 +280,7 @@ class MesosSchedulerBackendSuite extends SparkFunSuite with LocalSparkContext wi
     when(taskScheduler.resourceOffers(expectedWorkerOffers)).thenReturn(Seq(Seq(taskDesc)))
     when(taskScheduler.CPUS_PER_TASK).thenReturn(1)
 
-    val capture = ArgumentCaptor.forClass(classOf[util.Collection[TaskInfo]])
+    val capture = ArgumentCaptor.forClass(classOf[Collection[TaskInfo]])
     when(
       driver.launchTasks(
         Matchers.eq(Collections.singleton(mesosOffers.get(0).getId)),
@@ -304,7 +305,7 @@ class MesosSchedulerBackendSuite extends SparkFunSuite with LocalSparkContext wi
     assert(cpusDev.getName.equals("cpus"))
     assert(cpusDev.getScalar.getValue.equals(1.0))
     assert(cpusDev.getRole.equals("dev"))
-    val executorResources = taskInfo.getExecutor.getResourcesList
+    val executorResources = taskInfo.getExecutor.getResourcesList.asScala
     assert(executorResources.exists { r =>
       r.getName.equals("mem") && r.getScalar.getValue.equals(484.0) && r.getRole.equals("prod")
     })
diff --git a/core/src/test/scala/org/apache/spark/serializer/KryoSerializerSuite.scala b/core/src/test/scala/org/apache/spark/serializer/KryoSerializerSuite.scala
index 23a1fdb0f5..8d1c9d17e9 100644
--- a/core/src/test/scala/org/apache/spark/serializer/KryoSerializerSuite.scala
+++ b/core/src/test/scala/org/apache/spark/serializer/KryoSerializerSuite.scala
@@ -19,6 +19,7 @@ package org.apache.spark.serializer
 
 import java.io.{ByteArrayInputStream, ByteArrayOutputStream}
 
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.reflect.ClassTag
 
@@ -173,7 +174,7 @@ class KryoSerializerSuite extends SparkFunSuite with SharedSparkContext {
   test("asJavaIterable") {
     // Serialize a collection wrapped by asJavaIterable
     val ser = new KryoSerializer(conf).newInstance()
-    val a = ser.serialize(scala.collection.convert.WrapAsJava.asJavaIterable(Seq(12345)))
+    val a = ser.serialize(Seq(12345).asJava)
     val b = ser.deserialize[java.lang.Iterable[Int]](a)
     assert(b.iterator().next() === 12345)
 
diff --git a/core/src/test/scala/org/apache/spark/ui/UISeleniumSuite.scala b/core/src/test/scala/org/apache/spark/ui/UISeleniumSuite.scala
index 69888b2694..22e30ecaf0 100644
--- a/core/src/test/scala/org/apache/spark/ui/UISeleniumSuite.scala
+++ b/core/src/test/scala/org/apache/spark/ui/UISeleniumSuite.scala
@@ -21,7 +21,6 @@ import java.net.{HttpURLConnection, URL}
 import javax.servlet.http.{HttpServletResponse, HttpServletRequest}
 
 import scala.io.Source
-import scala.collection.JavaConversions._
 import scala.xml.Node
 
 import com.gargoylesoftware.htmlunit.DefaultCssErrorHandler
@@ -341,15 +340,15 @@ class UISeleniumSuite extends SparkFunSuite with WebBrowser with Matchers with B
         // The completed jobs table should have two rows. The first row will be the most recent job:
         val firstRow = find(cssSelector("tbody tr")).get.underlying
         val firstRowColumns = firstRow.findElements(By.tagName("td"))
-        firstRowColumns(0).getText should be ("1")
-        firstRowColumns(4).getText should be ("1/1 (2 skipped)")
-        firstRowColumns(5).getText should be ("8/8 (16 skipped)")
+        firstRowColumns.get(0).getText should be ("1")
+        firstRowColumns.get(4).getText should be ("1/1 (2 skipped)")
+        firstRowColumns.get(5).getText should be ("8/8 (16 skipped)")
         // The second row is the first run of the job, where nothing was skipped:
         val secondRow = findAll(cssSelector("tbody tr")).toSeq(1).underlying
         val secondRowColumns = secondRow.findElements(By.tagName("td"))
-        secondRowColumns(0).getText should be ("0")
-        secondRowColumns(4).getText should be ("3/3")
-        secondRowColumns(5).getText should be ("24/24")
+        secondRowColumns.get(0).getText should be ("0")
+        secondRowColumns.get(4).getText should be ("3/3")
+        secondRowColumns.get(5).getText should be ("24/24")
       }
     }
   }
@@ -502,8 +501,8 @@ class UISeleniumSuite extends SparkFunSuite with WebBrowser with Matchers with B
         for {
           (row, idx) <- rows.zipWithIndex
           columns = row.findElements(By.tagName("td"))
-          id = columns(0).getText()
-          description = columns(1).getText()
+          id = columns.get(0).getText()
+          description = columns.get(1).getText()
         } {
           id should be (expJobInfo(idx)._1)
           description should include (expJobInfo(idx)._2)
@@ -547,8 +546,8 @@ class UISeleniumSuite extends SparkFunSuite with WebBrowser with Matchers with B
         for {
           (row, idx) <- rows.zipWithIndex
           columns = row.findElements(By.tagName("td"))
-          id = columns(0).getText()
-          description = columns(1).getText()
+          id = columns.get(0).getText()
+          description = columns.get(1).getText()
         } {
           id should be (expStageInfo(idx)._1)
           description should include (expStageInfo(idx)._2)
diff --git a/examples/src/main/scala/org/apache/spark/examples/CassandraCQLTest.scala b/examples/src/main/scala/org/apache/spark/examples/CassandraCQLTest.scala
index 36832f51d2..fa07c1e501 100644
--- a/examples/src/main/scala/org/apache/spark/examples/CassandraCQLTest.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/CassandraCQLTest.scala
@@ -19,10 +19,7 @@
 package org.apache.spark.examples
 
 import java.nio.ByteBuffer
-
-import scala.collection.JavaConversions._
-import scala.collection.mutable.ListBuffer
-import scala.collection.immutable.Map
+import java.util.Collections
 
 import org.apache.cassandra.hadoop.ConfigHelper
 import org.apache.cassandra.hadoop.cql3.CqlPagingInputFormat
@@ -32,7 +29,6 @@ import org.apache.cassandra.utils.ByteBufferUtil
 import org.apache.hadoop.mapreduce.Job
 
 import org.apache.spark.{SparkConf, SparkContext}
-import org.apache.spark.SparkContext._
 
 
 /*
@@ -121,12 +117,9 @@ object CassandraCQLTest {
 
     val casoutputCF = aggregatedRDD.map {
       case (productId, saleCount) => {
-        val outColFamKey = Map("prod_id" -> ByteBufferUtil.bytes(productId))
-        val outKey: java.util.Map[String, ByteBuffer] = outColFamKey
-        var outColFamVal = new ListBuffer[ByteBuffer]
-        outColFamVal += ByteBufferUtil.bytes(saleCount)
-        val outVal: java.util.List[ByteBuffer] = outColFamVal
-       (outKey, outVal)
+        val outKey = Collections.singletonMap("prod_id", ByteBufferUtil.bytes(productId))
+        val outVal = Collections.singletonList(ByteBufferUtil.bytes(saleCount))
+        (outKey, outVal)
       }
     }
 
diff --git a/examples/src/main/scala/org/apache/spark/examples/CassandraTest.scala b/examples/src/main/scala/org/apache/spark/examples/CassandraTest.scala
index 96ef3e198e..2e56d24c60 100644
--- a/examples/src/main/scala/org/apache/spark/examples/CassandraTest.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/CassandraTest.scala
@@ -19,10 +19,9 @@
 package org.apache.spark.examples
 
 import java.nio.ByteBuffer
+import java.util.Arrays
 import java.util.SortedMap
 
-import scala.collection.JavaConversions._
-
 import org.apache.cassandra.db.IColumn
 import org.apache.cassandra.hadoop.ColumnFamilyOutputFormat
 import org.apache.cassandra.hadoop.ConfigHelper
@@ -32,7 +31,6 @@ import org.apache.cassandra.utils.ByteBufferUtil
 import org.apache.hadoop.mapreduce.Job
 
 import org.apache.spark.{SparkConf, SparkContext}
-import org.apache.spark.SparkContext._
 
 /*
  * This example demonstrates using Spark with Cassandra with the New Hadoop API and Cassandra
@@ -118,7 +116,7 @@ object CassandraTest {
 
         val outputkey = ByteBufferUtil.bytes(word + "-COUNT-" + System.currentTimeMillis)
 
-        val mutations: java.util.List[Mutation] = new Mutation() :: new Mutation() :: Nil
+        val mutations = Arrays.asList(new Mutation(), new Mutation())
         mutations.get(0).setColumn_or_supercolumn(new ColumnOrSuperColumn())
         mutations.get(0).column_or_supercolumn.setColumn(colWord)
         mutations.get(1).setColumn_or_supercolumn(new ColumnOrSuperColumn())
diff --git a/examples/src/main/scala/org/apache/spark/examples/DriverSubmissionTest.scala b/examples/src/main/scala/org/apache/spark/examples/DriverSubmissionTest.scala
index c42df2b884..bec61f3cd4 100644
--- a/examples/src/main/scala/org/apache/spark/examples/DriverSubmissionTest.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/DriverSubmissionTest.scala
@@ -18,7 +18,7 @@
 // scalastyle:off println
 package org.apache.spark.examples
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.util.Utils
 
@@ -36,10 +36,10 @@ object DriverSubmissionTest {
     val properties = Utils.getSystemProperties
 
     println("Environment variables containing SPARK_TEST:")
-    env.filter{case (k, v) => k.contains("SPARK_TEST")}.foreach(println)
+    env.asScala.filter { case (k, _) => k.contains("SPARK_TEST")}.foreach(println)
 
     println("System properties containing spark.test:")
-    properties.filter{case (k, v) => k.toString.contains("spark.test")}.foreach(println)
+    properties.filter { case (k, _) => k.toString.contains("spark.test") }.foreach(println)
 
     for (i <- 1 until numSecondsToSleep) {
       println(s"Alive for $i out of $numSecondsToSleep seconds")
diff --git a/examples/src/main/scala/org/apache/spark/examples/pythonconverters/AvroConverters.scala b/examples/src/main/scala/org/apache/spark/examples/pythonconverters/AvroConverters.scala
index 3ebb112fc0..805184e740 100644
--- a/examples/src/main/scala/org/apache/spark/examples/pythonconverters/AvroConverters.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/pythonconverters/AvroConverters.scala
@@ -19,7 +19,7 @@ package org.apache.spark.examples.pythonconverters
 
 import java.util.{Collection => JCollection, Map => JMap}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.avro.generic.{GenericFixed, IndexedRecord}
 import org.apache.avro.mapred.AvroWrapper
@@ -58,7 +58,7 @@ object AvroConversionUtil extends Serializable {
     val map = new java.util.HashMap[String, Any]
     obj match {
       case record: IndexedRecord =>
-        record.getSchema.getFields.zipWithIndex.foreach { case (f, i) =>
+        record.getSchema.getFields.asScala.zipWithIndex.foreach { case (f, i) =>
           map.put(f.name, fromAvro(record.get(i), f.schema))
         }
       case other => throw new SparkException(
@@ -68,9 +68,9 @@ object AvroConversionUtil extends Serializable {
   }
 
   def unpackMap(obj: Any, schema: Schema): JMap[String, Any] = {
-    obj.asInstanceOf[JMap[_, _]].map { case (key, value) =>
+    obj.asInstanceOf[JMap[_, _]].asScala.map { case (key, value) =>
       (key.toString, fromAvro(value, schema.getValueType))
-    }
+    }.asJava
   }
 
   def unpackFixed(obj: Any, schema: Schema): Array[Byte] = {
@@ -91,17 +91,17 @@ object AvroConversionUtil extends Serializable {
 
   def unpackArray(obj: Any, schema: Schema): JCollection[Any] = obj match {
     case c: JCollection[_] =>
-      c.map(fromAvro(_, schema.getElementType))
+      c.asScala.map(fromAvro(_, schema.getElementType)).toSeq.asJava
     case arr: Array[_] if arr.getClass.getComponentType.isPrimitive =>
-      arr.toSeq
+      arr.toSeq.asJava.asInstanceOf[JCollection[Any]]
     case arr: Array[_] =>
-      arr.map(fromAvro(_, schema.getElementType)).toSeq
+      arr.map(fromAvro(_, schema.getElementType)).toSeq.asJava
     case other => throw new SparkException(
       s"Unknown ARRAY type ${other.getClass.getName}")
   }
 
   def unpackUnion(obj: Any, schema: Schema): Any = {
-    schema.getTypes.toList match {
+    schema.getTypes.asScala.toList match {
       case List(s) => fromAvro(obj, s)
       case List(n, s) if n.getType == NULL => fromAvro(obj, s)
       case List(s, n) if n.getType == NULL => fromAvro(obj, s)
diff --git a/examples/src/main/scala/org/apache/spark/examples/pythonconverters/CassandraConverters.scala b/examples/src/main/scala/org/apache/spark/examples/pythonconverters/CassandraConverters.scala
index 83feb5703b..00ce47af48 100644
--- a/examples/src/main/scala/org/apache/spark/examples/pythonconverters/CassandraConverters.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/pythonconverters/CassandraConverters.scala
@@ -17,11 +17,13 @@
 
 package org.apache.spark.examples.pythonconverters
 
-import org.apache.spark.api.python.Converter
 import java.nio.ByteBuffer
+
+import scala.collection.JavaConverters._
+
 import org.apache.cassandra.utils.ByteBufferUtil
-import collection.JavaConversions._
 
+import org.apache.spark.api.python.Converter
 
 /**
  * Implementation of [[org.apache.spark.api.python.Converter]] that converts Cassandra
@@ -30,7 +32,7 @@ import collection.JavaConversions._
 class CassandraCQLKeyConverter extends Converter[Any, java.util.Map[String, Int]] {
   override def convert(obj: Any): java.util.Map[String, Int] = {
     val result = obj.asInstanceOf[java.util.Map[String, ByteBuffer]]
-    mapAsJavaMap(result.mapValues(bb => ByteBufferUtil.toInt(bb)))
+    result.asScala.mapValues(ByteBufferUtil.toInt).asJava
   }
 }
 
@@ -41,7 +43,7 @@ class CassandraCQLKeyConverter extends Converter[Any, java.util.Map[String, Int]
 class CassandraCQLValueConverter extends Converter[Any, java.util.Map[String, String]] {
   override def convert(obj: Any): java.util.Map[String, String] = {
     val result = obj.asInstanceOf[java.util.Map[String, ByteBuffer]]
-    mapAsJavaMap(result.mapValues(bb => ByteBufferUtil.string(bb)))
+    result.asScala.mapValues(ByteBufferUtil.string).asJava
   }
 }
 
@@ -52,7 +54,7 @@ class CassandraCQLValueConverter extends Converter[Any, java.util.Map[String, St
 class ToCassandraCQLKeyConverter extends Converter[Any, java.util.Map[String, ByteBuffer]] {
   override def convert(obj: Any): java.util.Map[String, ByteBuffer] = {
     val input = obj.asInstanceOf[java.util.Map[String, Int]]
-    mapAsJavaMap(input.mapValues(i => ByteBufferUtil.bytes(i)))
+    input.asScala.mapValues(ByteBufferUtil.bytes).asJava
   }
 }
 
@@ -63,6 +65,6 @@ class ToCassandraCQLKeyConverter extends Converter[Any, java.util.Map[String, By
 class ToCassandraCQLValueConverter extends Converter[Any, java.util.List[ByteBuffer]] {
   override def convert(obj: Any): java.util.List[ByteBuffer] = {
     val input = obj.asInstanceOf[java.util.List[String]]
-    seqAsJavaList(input.map(s => ByteBufferUtil.bytes(s)))
+    input.asScala.map(ByteBufferUtil.bytes).asJava
   }
 }
diff --git a/examples/src/main/scala/org/apache/spark/examples/pythonconverters/HBaseConverters.scala b/examples/src/main/scala/org/apache/spark/examples/pythonconverters/HBaseConverters.scala
index 90d48a6410..0a25ee7ae5 100644
--- a/examples/src/main/scala/org/apache/spark/examples/pythonconverters/HBaseConverters.scala
+++ b/examples/src/main/scala/org/apache/spark/examples/pythonconverters/HBaseConverters.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.examples.pythonconverters
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.parsing.json.JSONObject
 
 import org.apache.spark.api.python.Converter
@@ -33,7 +33,6 @@ import org.apache.hadoop.hbase.CellUtil
  */
 class HBaseResultToStringConverter extends Converter[Any, String] {
   override def convert(obj: Any): String = {
-    import collection.JavaConverters._
     val result = obj.asInstanceOf[Result]
     val output = result.listCells.asScala.map(cell =>
         Map(
@@ -77,7 +76,7 @@ class StringToImmutableBytesWritableConverter extends Converter[Any, ImmutableBy
  */
 class StringListToPutConverter extends Converter[Any, Put] {
   override def convert(obj: Any): Put = {
-    val output = obj.asInstanceOf[java.util.ArrayList[String]].map(Bytes.toBytes(_)).toArray
+    val output = obj.asInstanceOf[java.util.ArrayList[String]].asScala.map(Bytes.toBytes).toArray
     val put = new Put(output(0))
     put.add(output(1), output(2), output(3))
   }
diff --git a/external/flume-sink/src/test/scala/org/apache/spark/streaming/flume/sink/SparkSinkSuite.scala b/external/flume-sink/src/test/scala/org/apache/spark/streaming/flume/sink/SparkSinkSuite.scala
index fa43629d49..d2654700ea 100644
--- a/external/flume-sink/src/test/scala/org/apache/spark/streaming/flume/sink/SparkSinkSuite.scala
+++ b/external/flume-sink/src/test/scala/org/apache/spark/streaming/flume/sink/SparkSinkSuite.scala
@@ -20,7 +20,7 @@ import java.net.InetSocketAddress
 import java.util.concurrent.atomic.AtomicInteger
 import java.util.concurrent.{TimeUnit, CountDownLatch, Executors}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.concurrent.{ExecutionContext, Future}
 import scala.util.{Failure, Success}
 
@@ -166,7 +166,7 @@ class SparkSinkSuite extends FunSuite {
     channelContext.put("capacity", channelCapacity.toString)
     channelContext.put("transactionCapacity", 1000.toString)
     channelContext.put("keep-alive", 0.toString)
-    channelContext.putAll(overrides)
+    channelContext.putAll(overrides.asJava)
     channel.setName(scala.util.Random.nextString(10))
     channel.configure(channelContext)
 
diff --git a/external/flume/src/main/scala/org/apache/spark/streaming/flume/EventTransformer.scala b/external/flume/src/main/scala/org/apache/spark/streaming/flume/EventTransformer.scala
index 65c49c1315..48df27b268 100644
--- a/external/flume/src/main/scala/org/apache/spark/streaming/flume/EventTransformer.scala
+++ b/external/flume/src/main/scala/org/apache/spark/streaming/flume/EventTransformer.scala
@@ -19,7 +19,7 @@ package org.apache.spark.streaming.flume
 
 import java.io.{ObjectOutput, ObjectInput}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.util.Utils
 import org.apache.spark.Logging
@@ -60,7 +60,7 @@ private[streaming] object EventTransformer extends Logging {
     out.write(body)
     val numHeaders = headers.size()
     out.writeInt(numHeaders)
-    for ((k, v) <- headers) {
+    for ((k, v) <- headers.asScala) {
       val keyBuff = Utils.serialize(k.toString)
       out.writeInt(keyBuff.length)
       out.write(keyBuff)
diff --git a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeBatchFetcher.scala b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeBatchFetcher.scala
index 88cc2aa3bf..b9d4e762ca 100644
--- a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeBatchFetcher.scala
+++ b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeBatchFetcher.scala
@@ -16,7 +16,6 @@
  */
 package org.apache.spark.streaming.flume
 
-import scala.collection.JavaConversions._
 import scala.collection.mutable.ArrayBuffer
 
 import com.google.common.base.Throwables
@@ -155,7 +154,7 @@ private[flume] class FlumeBatchFetcher(receiver: FlumePollingReceiver) extends R
     val buffer = new ArrayBuffer[SparkFlumeEvent](events.size())
     var j = 0
     while (j < events.size()) {
-      val event = events(j)
+      val event = events.get(j)
       val sparkFlumeEvent = new SparkFlumeEvent()
       sparkFlumeEvent.event.setBody(event.getBody)
       sparkFlumeEvent.event.setHeaders(event.getHeaders)
diff --git a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeInputDStream.scala b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeInputDStream.scala
index 1e32a365a1..2bf99cb3cb 100644
--- a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeInputDStream.scala
+++ b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeInputDStream.scala
@@ -22,7 +22,7 @@ import java.io.{ObjectInput, ObjectOutput, Externalizable}
 import java.nio.ByteBuffer
 import java.util.concurrent.Executors
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
 import org.apache.flume.source.avro.AvroSourceProtocol
@@ -99,7 +99,7 @@ class SparkFlumeEvent() extends Externalizable {
 
     val numHeaders = event.getHeaders.size()
     out.writeInt(numHeaders)
-    for ((k, v) <- event.getHeaders) {
+    for ((k, v) <- event.getHeaders.asScala) {
       val keyBuff = Utils.serialize(k.toString)
       out.writeInt(keyBuff.length)
       out.write(keyBuff)
@@ -127,8 +127,7 @@ class FlumeEventServer(receiver : FlumeReceiver) extends AvroSourceProtocol {
   }
 
   override def appendBatch(events : java.util.List[AvroFlumeEvent]) : Status = {
-    events.foreach (event =>
-      receiver.store(SparkFlumeEvent.fromAvroFlumeEvent(event)))
+    events.asScala.foreach(event => receiver.store(SparkFlumeEvent.fromAvroFlumeEvent(event)))
     Status.OK
   }
 }
diff --git a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumePollingInputDStream.scala b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumePollingInputDStream.scala
index 583e7dca31..0bc46209b8 100644
--- a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumePollingInputDStream.scala
+++ b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumePollingInputDStream.scala
@@ -20,7 +20,7 @@ package org.apache.spark.streaming.flume
 import java.net.InetSocketAddress
 import java.util.concurrent.{LinkedBlockingQueue, Executors}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
 import com.google.common.util.concurrent.ThreadFactoryBuilder
@@ -94,9 +94,7 @@ private[streaming] class FlumePollingReceiver(
   override def onStop(): Unit = {
     logInfo("Shutting down Flume Polling Receiver")
     receiverExecutor.shutdownNow()
-    connections.foreach(connection => {
-      connection.transceiver.close()
-    })
+    connections.asScala.foreach(_.transceiver.close())
     channelFactory.releaseExternalResources()
   }
 
diff --git a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeTestUtils.scala b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeTestUtils.scala
index 9d9c3b1894..70018c86f9 100644
--- a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeTestUtils.scala
+++ b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeTestUtils.scala
@@ -19,9 +19,9 @@ package org.apache.spark.streaming.flume
 
 import java.net.{InetSocketAddress, ServerSocket}
 import java.nio.ByteBuffer
-import java.util.{List => JList}
+import java.util.Collections
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import com.google.common.base.Charsets.UTF_8
 import org.apache.avro.ipc.NettyTransceiver
@@ -59,13 +59,13 @@ private[flume] class FlumeTestUtils {
   }
 
   /** Send data to the flume receiver */
-  def writeInput(input: JList[String], enableCompression: Boolean): Unit = {
+  def writeInput(input: Seq[String], enableCompression: Boolean): Unit = {
     val testAddress = new InetSocketAddress("localhost", testPort)
 
     val inputEvents = input.map { item =>
       val event = new AvroFlumeEvent
       event.setBody(ByteBuffer.wrap(item.getBytes(UTF_8)))
-      event.setHeaders(Map[CharSequence, CharSequence]("test" -> "header"))
+      event.setHeaders(Collections.singletonMap("test", "header"))
       event
     }
 
@@ -88,7 +88,7 @@ private[flume] class FlumeTestUtils {
     }
 
     // Send data
-    val status = client.appendBatch(inputEvents.toList)
+    val status = client.appendBatch(inputEvents.asJava)
     if (status != avro.Status.OK) {
       throw new AssertionError("Sent events unsuccessfully")
     }
diff --git a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeUtils.scala b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeUtils.scala
index a65a9b921a..c719b80aca 100644
--- a/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeUtils.scala
+++ b/external/flume/src/main/scala/org/apache/spark/streaming/flume/FlumeUtils.scala
@@ -21,7 +21,7 @@ import java.net.InetSocketAddress
 import java.io.{DataOutputStream, ByteArrayOutputStream}
 import java.util.{List => JList, Map => JMap}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.api.java.function.PairFunction
 import org.apache.spark.api.python.PythonRDD
@@ -268,8 +268,8 @@ private[flume] class FlumeUtilsPythonHelper {
       maxBatchSize: Int,
       parallelism: Int
     ): JavaPairDStream[Array[Byte], Array[Byte]] = {
-    assert(hosts.length == ports.length)
-    val addresses = hosts.zip(ports).map {
+    assert(hosts.size() == ports.size())
+    val addresses = hosts.asScala.zip(ports.asScala).map {
       case (host, port) => new InetSocketAddress(host, port)
     }
     val dstream = FlumeUtils.createPollingStream(
@@ -286,7 +286,7 @@ private object FlumeUtilsPythonHelper {
     val output = new DataOutputStream(byteStream)
     try {
       output.writeInt(map.size)
-      map.foreach { kv =>
+      map.asScala.foreach { kv =>
         PythonRDD.writeUTF(kv._1.toString, output)
         PythonRDD.writeUTF(kv._2.toString, output)
       }
diff --git a/external/flume/src/main/scala/org/apache/spark/streaming/flume/PollingFlumeTestUtils.scala b/external/flume/src/main/scala/org/apache/spark/streaming/flume/PollingFlumeTestUtils.scala
index 91d63d49db..a2ab320957 100644
--- a/external/flume/src/main/scala/org/apache/spark/streaming/flume/PollingFlumeTestUtils.scala
+++ b/external/flume/src/main/scala/org/apache/spark/streaming/flume/PollingFlumeTestUtils.scala
@@ -18,9 +18,8 @@
 package org.apache.spark.streaming.flume
 
 import java.util.concurrent._
-import java.util.{List => JList, Map => JMap}
+import java.util.{Map => JMap, Collections}
 
-import scala.collection.JavaConversions._
 import scala.collection.mutable.ArrayBuffer
 
 import com.google.common.base.Charsets.UTF_8
@@ -77,7 +76,7 @@ private[flume] class PollingFlumeTestUtils {
   /**
    * Start 2 sinks and return the ports
    */
-  def startMultipleSinks(): JList[Int] = {
+  def startMultipleSinks(): Seq[Int] = {
     channels.clear()
     sinks.clear()
 
@@ -138,8 +137,7 @@ private[flume] class PollingFlumeTestUtils {
   /**
    * A Python-friendly method to assert the output
    */
-  def assertOutput(
-      outputHeaders: JList[JMap[String, String]], outputBodies: JList[String]): Unit = {
+  def assertOutput(outputHeaders: Seq[JMap[String, String]], outputBodies: Seq[String]): Unit = {
     require(outputHeaders.size == outputBodies.size)
     val eventSize = outputHeaders.size
     if (eventSize != totalEventsPerChannel * channels.size) {
@@ -149,12 +147,12 @@ private[flume] class PollingFlumeTestUtils {
     var counter = 0
     for (k <- 0 until channels.size; i <- 0 until totalEventsPerChannel) {
       val eventBodyToVerify = s"${channels(k).getName}-$i"
-      val eventHeaderToVerify: JMap[String, String] = Map[String, String](s"test-$i" -> "header")
+      val eventHeaderToVerify: JMap[String, String] = Collections.singletonMap(s"test-$i", "header")
       var found = false
       var j = 0
       while (j < eventSize && !found) {
-        if (eventBodyToVerify == outputBodies.get(j) &&
-          eventHeaderToVerify == outputHeaders.get(j)) {
+        if (eventBodyToVerify == outputBodies(j) &&
+          eventHeaderToVerify == outputHeaders(j)) {
           found = true
           counter += 1
         }
@@ -195,7 +193,7 @@ private[flume] class PollingFlumeTestUtils {
         tx.begin()
         for (j <- 0 until eventsPerBatch) {
           channel.put(EventBuilder.withBody(s"${channel.getName}-$t".getBytes(UTF_8),
-            Map[String, String](s"test-$t" -> "header")))
+            Collections.singletonMap(s"test-$t", "header")))
           t += 1
         }
         tx.commit()
diff --git a/external/flume/src/test/scala/org/apache/spark/streaming/flume/FlumePollingStreamSuite.scala b/external/flume/src/test/scala/org/apache/spark/streaming/flume/FlumePollingStreamSuite.scala
index d5f9a0aa38..ff2fb8eed2 100644
--- a/external/flume/src/test/scala/org/apache/spark/streaming/flume/FlumePollingStreamSuite.scala
+++ b/external/flume/src/test/scala/org/apache/spark/streaming/flume/FlumePollingStreamSuite.scala
@@ -19,7 +19,7 @@ package org.apache.spark.streaming.flume
 
 import java.net.InetSocketAddress
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{SynchronizedBuffer, ArrayBuffer}
 import scala.concurrent.duration._
 import scala.language.postfixOps
@@ -116,9 +116,9 @@ class FlumePollingStreamSuite extends SparkFunSuite with BeforeAndAfter with Log
       // The eventually is required to ensure that all data in the batch has been processed.
       eventually(timeout(10 seconds), interval(100 milliseconds)) {
         val flattenOutputBuffer = outputBuffer.flatten
-        val headers = flattenOutputBuffer.map(_.event.getHeaders.map {
-          case kv => (kv._1.toString, kv._2.toString)
-        }).map(mapAsJavaMap)
+        val headers = flattenOutputBuffer.map(_.event.getHeaders.asScala.map {
+          case (key, value) => (key.toString, value.toString)
+        }).map(_.asJava)
         val bodies = flattenOutputBuffer.map(e => new String(e.event.getBody.array(), UTF_8))
         utils.assertOutput(headers, bodies)
       }
diff --git a/external/flume/src/test/scala/org/apache/spark/streaming/flume/FlumeStreamSuite.scala b/external/flume/src/test/scala/org/apache/spark/streaming/flume/FlumeStreamSuite.scala
index 5bc4cdf653..5ffb60bd60 100644
--- a/external/flume/src/test/scala/org/apache/spark/streaming/flume/FlumeStreamSuite.scala
+++ b/external/flume/src/test/scala/org/apache/spark/streaming/flume/FlumeStreamSuite.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.streaming.flume
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{ArrayBuffer, SynchronizedBuffer}
 import scala.concurrent.duration._
 import scala.language.postfixOps
diff --git a/external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaTestUtils.scala b/external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaTestUtils.scala
index 79a9db4291..c9fd715d3d 100644
--- a/external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaTestUtils.scala
+++ b/external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaTestUtils.scala
@@ -24,6 +24,7 @@ import java.util.concurrent.TimeoutException
 import java.util.{Map => JMap, Properties}
 
 import scala.annotation.tailrec
+import scala.collection.JavaConverters._
 import scala.language.postfixOps
 import scala.util.control.NonFatal
 
@@ -159,8 +160,7 @@ private[kafka] class KafkaTestUtils extends Logging {
 
   /** Java-friendly function for sending messages to the Kafka broker */
   def sendMessages(topic: String, messageToFreq: JMap[String, JInt]): Unit = {
-    import scala.collection.JavaConversions._
-    sendMessages(topic, Map(messageToFreq.mapValues(_.intValue()).toSeq: _*))
+    sendMessages(topic, Map(messageToFreq.asScala.mapValues(_.intValue()).toSeq: _*))
   }
 
   /** Send the messages to the Kafka broker */
diff --git a/external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaUtils.scala b/external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaUtils.scala
index 388dbb8184..3128222077 100644
--- a/external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaUtils.scala
+++ b/external/kafka/src/main/scala/org/apache/spark/streaming/kafka/KafkaUtils.scala
@@ -20,7 +20,7 @@ package org.apache.spark.streaming.kafka
 import java.lang.{Integer => JInt, Long => JLong}
 import java.util.{List => JList, Map => JMap, Set => JSet}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
 import kafka.common.TopicAndPartition
@@ -96,7 +96,7 @@ object KafkaUtils {
       groupId: String,
       topics: JMap[String, JInt]
     ): JavaPairReceiverInputDStream[String, String] = {
-    createStream(jssc.ssc, zkQuorum, groupId, Map(topics.mapValues(_.intValue()).toSeq: _*))
+    createStream(jssc.ssc, zkQuorum, groupId, Map(topics.asScala.mapValues(_.intValue()).toSeq: _*))
   }
 
   /**
@@ -115,7 +115,7 @@ object KafkaUtils {
       topics: JMap[String, JInt],
       storageLevel: StorageLevel
     ): JavaPairReceiverInputDStream[String, String] = {
-    createStream(jssc.ssc, zkQuorum, groupId, Map(topics.mapValues(_.intValue()).toSeq: _*),
+    createStream(jssc.ssc, zkQuorum, groupId, Map(topics.asScala.mapValues(_.intValue()).toSeq: _*),
       storageLevel)
   }
 
@@ -149,7 +149,10 @@ object KafkaUtils {
     implicit val valueCmd: ClassTag[T] = ClassTag(valueDecoderClass)
 
     createStream[K, V, U, T](
-      jssc.ssc, kafkaParams.toMap, Map(topics.mapValues(_.intValue()).toSeq: _*), storageLevel)
+      jssc.ssc,
+      kafkaParams.asScala.toMap,
+      Map(topics.asScala.mapValues(_.intValue()).toSeq: _*),
+      storageLevel)
   }
 
   /** get leaders for the given offset ranges, or throw an exception */
@@ -275,7 +278,7 @@ object KafkaUtils {
     implicit val keyDecoderCmt: ClassTag[KD] = ClassTag(keyDecoderClass)
     implicit val valueDecoderCmt: ClassTag[VD] = ClassTag(valueDecoderClass)
     new JavaPairRDD(createRDD[K, V, KD, VD](
-      jsc.sc, Map(kafkaParams.toSeq: _*), offsetRanges))
+      jsc.sc, Map(kafkaParams.asScala.toSeq: _*), offsetRanges))
   }
 
   /**
@@ -311,9 +314,9 @@ object KafkaUtils {
     implicit val keyDecoderCmt: ClassTag[KD] = ClassTag(keyDecoderClass)
     implicit val valueDecoderCmt: ClassTag[VD] = ClassTag(valueDecoderClass)
     implicit val recordCmt: ClassTag[R] = ClassTag(recordClass)
-    val leaderMap = Map(leaders.toSeq: _*)
+    val leaderMap = Map(leaders.asScala.toSeq: _*)
     createRDD[K, V, KD, VD, R](
-      jsc.sc, Map(kafkaParams.toSeq: _*), offsetRanges, leaderMap, messageHandler.call _)
+      jsc.sc, Map(kafkaParams.asScala.toSeq: _*), offsetRanges, leaderMap, messageHandler.call(_))
   }
 
   /**
@@ -476,8 +479,8 @@ object KafkaUtils {
     val cleanedHandler = jssc.sparkContext.clean(messageHandler.call _)
     createDirectStream[K, V, KD, VD, R](
       jssc.ssc,
-      Map(kafkaParams.toSeq: _*),
-      Map(fromOffsets.mapValues { _.longValue() }.toSeq: _*),
+      Map(kafkaParams.asScala.toSeq: _*),
+      Map(fromOffsets.asScala.mapValues(_.longValue()).toSeq: _*),
       cleanedHandler
     )
   }
@@ -531,8 +534,8 @@ object KafkaUtils {
     implicit val valueDecoderCmt: ClassTag[VD] = ClassTag(valueDecoderClass)
     createDirectStream[K, V, KD, VD](
       jssc.ssc,
-      Map(kafkaParams.toSeq: _*),
-      Set(topics.toSeq: _*)
+      Map(kafkaParams.asScala.toSeq: _*),
+      Set(topics.asScala.toSeq: _*)
     )
   }
 }
@@ -602,10 +605,10 @@ private[kafka] class KafkaUtilsPythonHelper {
     ): JavaPairInputDStream[Array[Byte], Array[Byte]] = {
 
     if (!fromOffsets.isEmpty) {
-      import scala.collection.JavaConversions._
-      val topicsFromOffsets = fromOffsets.keySet().map(_.topic)
-      if (topicsFromOffsets != topics.toSet) {
-        throw new IllegalStateException(s"The specified topics: ${topics.toSet.mkString(" ")} " +
+      val topicsFromOffsets = fromOffsets.keySet().asScala.map(_.topic)
+      if (topicsFromOffsets != topics.asScala.toSet) {
+        throw new IllegalStateException(
+          s"The specified topics: ${topics.asScala.toSet.mkString(" ")} " +
           s"do not equal to the topic from offsets: ${topicsFromOffsets.mkString(" ")}")
       }
     }
@@ -663,6 +666,6 @@ private[kafka] class KafkaUtilsPythonHelper {
         "with this RDD, please call this method only on a Kafka RDD.")
 
     val kafkaRDD = kafkaRDDs.head.asInstanceOf[KafkaRDD[_, _, _, _, _]]
-    kafkaRDD.offsetRanges.toSeq
+    kafkaRDD.offsetRanges.toSeq.asJava
   }
 }
diff --git a/external/zeromq/src/main/scala/org/apache/spark/streaming/zeromq/ZeroMQUtils.scala b/external/zeromq/src/main/scala/org/apache/spark/streaming/zeromq/ZeroMQUtils.scala
index 0469d0af88..4ea218eaa4 100644
--- a/external/zeromq/src/main/scala/org/apache/spark/streaming/zeromq/ZeroMQUtils.scala
+++ b/external/zeromq/src/main/scala/org/apache/spark/streaming/zeromq/ZeroMQUtils.scala
@@ -18,15 +18,17 @@
 package org.apache.spark.streaming.zeromq
 
 import scala.reflect.ClassTag
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
+
 import akka.actor.{Props, SupervisorStrategy}
 import akka.util.ByteString
 import akka.zeromq.Subscribe
+
 import org.apache.spark.api.java.function.{Function => JFunction}
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.streaming.StreamingContext
 import org.apache.spark.streaming.api.java.{JavaReceiverInputDStream, JavaStreamingContext}
-import org.apache.spark.streaming.dstream.{ReceiverInputDStream}
+import org.apache.spark.streaming.dstream.ReceiverInputDStream
 import org.apache.spark.streaming.receiver.ActorSupervisorStrategy
 
 object ZeroMQUtils {
@@ -75,7 +77,8 @@ object ZeroMQUtils {
     ): JavaReceiverInputDStream[T] = {
     implicit val cm: ClassTag[T] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[T]]
-    val fn = (x: Seq[ByteString]) => bytesToObjects.call(x.map(_.toArray).toArray).toIterator
+    val fn =
+      (x: Seq[ByteString]) => bytesToObjects.call(x.map(_.toArray).toArray).iterator().asScala
     createStream[T](jssc.ssc, publisherUrl, subscribe, fn, storageLevel, supervisorStrategy)
   }
 
@@ -99,7 +102,8 @@ object ZeroMQUtils {
     ): JavaReceiverInputDStream[T] = {
     implicit val cm: ClassTag[T] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[T]]
-    val fn = (x: Seq[ByteString]) => bytesToObjects.call(x.map(_.toArray).toArray).toIterator
+    val fn =
+      (x: Seq[ByteString]) => bytesToObjects.call(x.map(_.toArray).toArray).iterator().asScala
     createStream[T](jssc.ssc, publisherUrl, subscribe, fn, storageLevel)
   }
 
@@ -122,7 +126,8 @@ object ZeroMQUtils {
     ): JavaReceiverInputDStream[T] = {
     implicit val cm: ClassTag[T] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[T]]
-    val fn = (x: Seq[ByteString]) => bytesToObjects.call(x.map(_.toArray).toArray).toIterator
+    val fn =
+      (x: Seq[ByteString]) => bytesToObjects.call(x.map(_.toArray).toArray).iterator().asScala
     createStream[T](jssc.ssc, publisherUrl, subscribe, fn)
   }
 }
diff --git a/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisBackedBlockRDD.scala b/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisBackedBlockRDD.scala
index a003ddf325..5d32fa699a 100644
--- a/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisBackedBlockRDD.scala
+++ b/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisBackedBlockRDD.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.streaming.kinesis
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.control.NonFatal
 
 import com.amazonaws.auth.{AWSCredentials, DefaultAWSCredentialsProviderChain}
@@ -213,7 +213,7 @@ class KinesisSequenceRangeIterator(
       s"getting records using shard iterator") {
         client.getRecords(getRecordsRequest)
       }
-    (getRecordsResult.getRecords.iterator(), getRecordsResult.getNextShardIterator)
+    (getRecordsResult.getRecords.iterator().asScala, getRecordsResult.getNextShardIterator)
   }
 
   /**
diff --git a/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisReceiver.scala b/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisReceiver.scala
index 22324e821c..6e0988c1af 100644
--- a/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisReceiver.scala
+++ b/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisReceiver.scala
@@ -18,7 +18,7 @@ package org.apache.spark.streaming.kinesis
 
 import java.util.UUID
 
-import scala.collection.JavaConversions.asScalaIterator
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.util.control.NonFatal
 
@@ -202,7 +202,7 @@ private[kinesis] class KinesisReceiver(
   /** Add records of the given shard to the current block being generated */
   private[kinesis] def addRecords(shardId: String, records: java.util.List[Record]): Unit = {
     if (records.size > 0) {
-      val dataIterator = records.iterator().map { record =>
+      val dataIterator = records.iterator().asScala.map { record =>
         val byteBuffer = record.getData()
         val byteArray = new Array[Byte](byteBuffer.remaining())
         byteBuffer.get(byteArray)
diff --git a/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisTestUtils.scala b/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisTestUtils.scala
index c8eec13ec7..634bf94521 100644
--- a/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisTestUtils.scala
+++ b/extras/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisTestUtils.scala
@@ -20,6 +20,7 @@ package org.apache.spark.streaming.kinesis
 import java.nio.ByteBuffer
 import java.util.concurrent.TimeUnit
 
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
 import scala.util.{Failure, Random, Success, Try}
@@ -115,7 +116,7 @@ private[kinesis] class KinesisTestUtils extends Logging {
    * Expose a Python friendly API.
    */
   def pushData(testData: java.util.List[Int]): Unit = {
-    pushData(scala.collection.JavaConversions.asScalaBuffer(testData))
+    pushData(testData.asScala)
   }
 
   def deleteStream(): Unit = {
diff --git a/extras/kinesis-asl/src/test/scala/org/apache/spark/streaming/kinesis/KinesisReceiverSuite.scala b/extras/kinesis-asl/src/test/scala/org/apache/spark/streaming/kinesis/KinesisReceiverSuite.scala
index ceb135e065..3d136aec2e 100644
--- a/extras/kinesis-asl/src/test/scala/org/apache/spark/streaming/kinesis/KinesisReceiverSuite.scala
+++ b/extras/kinesis-asl/src/test/scala/org/apache/spark/streaming/kinesis/KinesisReceiverSuite.scala
@@ -17,10 +17,10 @@
 package org.apache.spark.streaming.kinesis
 
 import java.nio.ByteBuffer
+import java.nio.charset.StandardCharsets
+import java.util.Arrays
 
-import scala.collection.JavaConversions.seqAsJavaList
-
-import com.amazonaws.services.kinesis.clientlibrary.exceptions.{InvalidStateException, KinesisClientLibDependencyException, ShutdownException, ThrottlingException}
+import com.amazonaws.services.kinesis.clientlibrary.exceptions._
 import com.amazonaws.services.kinesis.clientlibrary.interfaces.IRecordProcessorCheckpointer
 import com.amazonaws.services.kinesis.clientlibrary.types.ShutdownReason
 import com.amazonaws.services.kinesis.model.Record
@@ -47,10 +47,10 @@ class KinesisReceiverSuite extends TestSuiteBase with Matchers with BeforeAndAft
   val someSeqNum = Some(seqNum)
 
   val record1 = new Record()
-  record1.setData(ByteBuffer.wrap("Spark In Action".getBytes()))
+  record1.setData(ByteBuffer.wrap("Spark In Action".getBytes(StandardCharsets.UTF_8)))
   val record2 = new Record()
-  record2.setData(ByteBuffer.wrap("Learning Spark".getBytes()))
-  val batch = List[Record](record1, record2)
+  record2.setData(ByteBuffer.wrap("Learning Spark".getBytes(StandardCharsets.UTF_8)))
+  val batch = Arrays.asList(record1, record2)
 
   var receiverMock: KinesisReceiver = _
   var checkpointerMock: IRecordProcessorCheckpointer = _
diff --git a/mllib/src/main/scala/org/apache/spark/mllib/util/LinearDataGenerator.scala b/mllib/src/main/scala/org/apache/spark/mllib/util/LinearDataGenerator.scala
index 87eeb5db05..7a1c779606 100644
--- a/mllib/src/main/scala/org/apache/spark/mllib/util/LinearDataGenerator.scala
+++ b/mllib/src/main/scala/org/apache/spark/mllib/util/LinearDataGenerator.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.mllib.util
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.Random
 
 import com.github.fommil.netlib.BLAS.{getInstance => blas}
@@ -52,7 +52,7 @@ object LinearDataGenerator {
       nPoints: Int,
       seed: Int,
       eps: Double): java.util.List[LabeledPoint] = {
-    seqAsJavaList(generateLinearInput(intercept, weights, nPoints, seed, eps))
+    generateLinearInput(intercept, weights, nPoints, seed, eps).asJava
   }
 
   /**
diff --git a/mllib/src/test/java/org/apache/spark/ml/classification/JavaOneVsRestSuite.java b/mllib/src/test/java/org/apache/spark/ml/classification/JavaOneVsRestSuite.java
index a1ee554152..2744e020e9 100644
--- a/mllib/src/test/java/org/apache/spark/ml/classification/JavaOneVsRestSuite.java
+++ b/mllib/src/test/java/org/apache/spark/ml/classification/JavaOneVsRestSuite.java
@@ -20,7 +20,7 @@ package org.apache.spark.ml.classification;
 import java.io.Serializable;
 import java.util.List;
 
-import static scala.collection.JavaConversions.seqAsJavaList;
+import scala.collection.JavaConverters;
 
 import org.junit.After;
 import org.junit.Assert;
@@ -55,8 +55,9 @@ public class JavaOneVsRestSuite implements Serializable {
 
         double[] xMean = {5.843, 3.057, 3.758, 1.199};
         double[] xVariance = {0.6856, 0.1899, 3.116, 0.581};
-        List<LabeledPoint> points = seqAsJavaList(generateMultinomialLogisticInput(
-                weights, xMean, xVariance, true, nPoints, 42));
+        List<LabeledPoint> points = JavaConverters.asJavaListConverter(
+            generateMultinomialLogisticInput(weights, xMean, xVariance, true, nPoints, 42)
+        ).asJava();
         datasetRDD = jsc.parallelize(points, 2);
         dataset = jsql.createDataFrame(datasetRDD, LabeledPoint.class);
     }
diff --git a/mllib/src/test/scala/org/apache/spark/mllib/classification/LogisticRegressionSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/classification/LogisticRegressionSuite.scala
index 2473510e13..8d14bb6572 100644
--- a/mllib/src/test/scala/org/apache/spark/mllib/classification/LogisticRegressionSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/mllib/classification/LogisticRegressionSuite.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.mllib.classification
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.Random
 import scala.util.control.Breaks._
 
@@ -38,7 +38,7 @@ object LogisticRegressionSuite {
     scale: Double,
     nPoints: Int,
     seed: Int): java.util.List[LabeledPoint] = {
-    seqAsJavaList(generateLogisticInput(offset, scale, nPoints, seed))
+    generateLogisticInput(offset, scale, nPoints, seed).asJava
   }
 
   // Generate input of the form Y = logistic(offset + scale*X)
diff --git a/mllib/src/test/scala/org/apache/spark/mllib/classification/SVMSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/classification/SVMSuite.scala
index b1d78cba9e..ee3c85d09a 100644
--- a/mllib/src/test/scala/org/apache/spark/mllib/classification/SVMSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/mllib/classification/SVMSuite.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.mllib.classification
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.Random
 
 import org.jblas.DoubleMatrix
@@ -35,7 +35,7 @@ object SVMSuite {
     weights: Array[Double],
     nPoints: Int,
     seed: Int): java.util.List[LabeledPoint] = {
-    seqAsJavaList(generateSVMInput(intercept, weights, nPoints, seed))
+    generateSVMInput(intercept, weights, nPoints, seed).asJava
   }
 
   // Generate noisy input of the form Y = signum(x.dot(weights) + intercept + noise)
diff --git a/mllib/src/test/scala/org/apache/spark/mllib/optimization/GradientDescentSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/optimization/GradientDescentSuite.scala
index 13b754a039..36ac7d2672 100644
--- a/mllib/src/test/scala/org/apache/spark/mllib/optimization/GradientDescentSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/mllib/optimization/GradientDescentSuite.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.mllib.optimization
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.Random
 
 import org.scalatest.Matchers
@@ -35,7 +35,7 @@ object GradientDescentSuite {
       scale: Double,
       nPoints: Int,
       seed: Int): java.util.List[LabeledPoint] = {
-    seqAsJavaList(generateGDInput(offset, scale, nPoints, seed))
+    generateGDInput(offset, scale, nPoints, seed).asJava
   }
 
   // Generate input of the form Y = logistic(offset + scale * X)
diff --git a/mllib/src/test/scala/org/apache/spark/mllib/recommendation/ALSSuite.scala b/mllib/src/test/scala/org/apache/spark/mllib/recommendation/ALSSuite.scala
index 05b87728d6..045135f7f8 100644
--- a/mllib/src/test/scala/org/apache/spark/mllib/recommendation/ALSSuite.scala
+++ b/mllib/src/test/scala/org/apache/spark/mllib/recommendation/ALSSuite.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.mllib.recommendation
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.math.abs
 import scala.util.Random
 
@@ -38,7 +38,7 @@ object ALSSuite {
       negativeWeights: Boolean): (java.util.List[Rating], DoubleMatrix, DoubleMatrix) = {
     val (sampledRatings, trueRatings, truePrefs) =
       generateRatings(users, products, features, samplingRate, implicitPrefs)
-    (seqAsJavaList(sampledRatings), trueRatings, truePrefs)
+    (sampledRatings.asJava, trueRatings, truePrefs)
   }
 
   def generateRatings(
diff --git a/project/SparkBuild.scala b/project/SparkBuild.scala
index 04e0d49b17..ea52bfd679 100644
--- a/project/SparkBuild.scala
+++ b/project/SparkBuild.scala
@@ -18,13 +18,13 @@
 import java.io._
 
 import scala.util.Properties
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import sbt._
 import sbt.Classpaths.publishTask
 import sbt.Keys._
 import sbtunidoc.Plugin.UnidocKeys.unidocGenjavadocVersion
-import com.typesafe.sbt.pom.{loadEffectivePom, PomBuild, SbtPomKeys}
+import com.typesafe.sbt.pom.{PomBuild, SbtPomKeys}
 import net.virtualvoid.sbt.graph.Plugin.graphSettings
 
 import spray.revolver.RevolverPlugin._
@@ -120,7 +120,7 @@ object SparkBuild extends PomBuild {
     case _ =>
   }
 
-  override val userPropertiesMap = System.getProperties.toMap
+  override val userPropertiesMap = System.getProperties.asScala.toMap
 
   lazy val MavenCompile = config("m2r") extend(Compile)
   lazy val publishLocalBoth = TaskKey[Unit]("publish-local", "publish local for m2 and ivy")
@@ -559,7 +559,7 @@ object TestSettings {
     javaOptions in Test += "-Dspark.unsafe.exceptionOnMemoryLeak=true",
     javaOptions in Test += "-Dsun.io.serialization.extendedDebugInfo=true",
     javaOptions in Test += "-Dderby.system.durability=test",
-    javaOptions in Test ++= System.getProperties.filter(_._1 startsWith "spark")
+    javaOptions in Test ++= System.getProperties.asScala.filter(_._1.startsWith("spark"))
       .map { case (k,v) => s"-D$k=$v" }.toSeq,
     javaOptions in Test += "-ea",
     javaOptions in Test ++= "-Xmx3g -Xss4096k -XX:PermSize=128M -XX:MaxNewSize=256m -XX:MaxPermSize=1g"
diff --git a/python/pyspark/sql/column.py b/python/pyspark/sql/column.py
index 8af8637cf9..0948f9b27c 100644
--- a/python/pyspark/sql/column.py
+++ b/python/pyspark/sql/column.py
@@ -61,6 +61,18 @@ def _to_seq(sc, cols, converter=None):
     return sc._jvm.PythonUtils.toSeq(cols)
 
 
+def _to_list(sc, cols, converter=None):
+    """
+    Convert a list of Column (or names) into a JVM (Scala) List of Column.
+
+    An optional `converter` could be used to convert items in `cols`
+    into JVM Column objects.
+    """
+    if converter:
+        cols = [converter(c) for c in cols]
+    return sc._jvm.PythonUtils.toList(cols)
+
+
 def _unary_op(name, doc="unary operator"):
     """ Create a method for given unary operator """
     def _(self):
diff --git a/python/pyspark/sql/dataframe.py b/python/pyspark/sql/dataframe.py
index 025811f519..e269ef4304 100644
--- a/python/pyspark/sql/dataframe.py
+++ b/python/pyspark/sql/dataframe.py
@@ -32,7 +32,7 @@ from pyspark.storagelevel import StorageLevel
 from pyspark.traceback_utils import SCCallSiteSync
 from pyspark.sql import since
 from pyspark.sql.types import _parse_datatype_json_string
-from pyspark.sql.column import Column, _to_seq, _to_java_column
+from pyspark.sql.column import Column, _to_seq, _to_list, _to_java_column
 from pyspark.sql.readwriter import DataFrameWriter
 from pyspark.sql.types import *
 
@@ -494,7 +494,7 @@ class DataFrame(object):
             if w < 0.0:
                 raise ValueError("Weights must be positive. Found weight value: %s" % w)
         seed = seed if seed is not None else random.randint(0, sys.maxsize)
-        rdd_array = self._jdf.randomSplit(_to_seq(self.sql_ctx._sc, weights), long(seed))
+        rdd_array = self._jdf.randomSplit(_to_list(self.sql_ctx._sc, weights), long(seed))
         return [DataFrame(rdd, self.sql_ctx) for rdd in rdd_array]
 
     @property
diff --git a/scalastyle-config.xml b/scalastyle-config.xml
index b5e2e882d2..68fdb4141c 100644
--- a/scalastyle-config.xml
+++ b/scalastyle-config.xml
@@ -161,6 +161,13 @@ This file is divided into 3 sections:
     ]]></customMessage>
   </check>
 
+  <!-- As of SPARK-9613 JavaConversions should be replaced with JavaConverters -->
+  <check customId="javaconversions" level="error" class="org.scalastyle.scalariform.TokenChecker" enabled="true">
+    <parameters><parameter name="regex">JavaConversions</parameter></parameters>
+    <customMessage>Instead of importing implicits in scala.collection.JavaConversions._, import
+    scala.collection.JavaConverters._ and use .asScala / .asJava methods</customMessage>
+  </check>
+
   <!-- ================================================================================ -->
   <!--       rules we'd like to enforce, but haven't cleaned up the codebase yet        -->
   <!-- ================================================================================ -->
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/Row.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/Row.scala
index ec895af9c3..cfd9cb0e62 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/Row.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/Row.scala
@@ -17,6 +17,8 @@
 
 package org.apache.spark.sql
 
+import scala.collection.JavaConverters._
+
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.expressions.GenericRow
 import org.apache.spark.sql.types.StructType
@@ -280,9 +282,8 @@ trait Row extends Serializable {
    *
    * @throws ClassCastException when data type does not match.
    */
-  def getList[T](i: Int): java.util.List[T] = {
-    scala.collection.JavaConversions.seqAsJavaList(getSeq[T](i))
-  }
+  def getList[T](i: Int): java.util.List[T] =
+    getSeq[T](i).asJava
 
   /**
    * Returns the value at position i of map type as a Scala Map.
@@ -296,9 +297,8 @@ trait Row extends Serializable {
    *
    * @throws ClassCastException when data type does not match.
    */
-  def getJavaMap[K, V](i: Int): java.util.Map[K, V] = {
-    scala.collection.JavaConversions.mapAsJavaMap(getMap[K, V](i))
-  }
+  def getJavaMap[K, V](i: Int): java.util.Map[K, V] =
+    getMap[K, V](i).asJava
 
   /**
    * Returns the value at position i of struct type as an [[Row]] object.
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Catalog.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Catalog.scala
index 503c4f4b20..4cc9a5520a 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Catalog.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Catalog.scala
@@ -19,7 +19,7 @@ package org.apache.spark.sql.catalyst.analysis
 
 import java.util.concurrent.ConcurrentHashMap
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
 
@@ -147,7 +147,7 @@ class SimpleCatalog(val conf: CatalystConf) extends Catalog {
 
   override def getTables(databaseName: Option[String]): Seq[(String, Boolean)] = {
     val result = ArrayBuffer.empty[(String, Boolean)]
-    for (name <- tables.keySet()) {
+    for (name <- tables.keySet().asScala) {
       result += ((name, true))
     }
     result
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/DataFrameNaFunctions.scala b/sql/core/src/main/scala/org/apache/spark/sql/DataFrameNaFunctions.scala
index a4fd4cf3b3..77a42c0873 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/DataFrameNaFunctions.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/DataFrameNaFunctions.scala
@@ -19,7 +19,7 @@ package org.apache.spark.sql
 
 import java.{lang => jl}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.annotation.Experimental
 import org.apache.spark.sql.catalyst.expressions._
@@ -209,7 +209,7 @@ final class DataFrameNaFunctions private[sql](df: DataFrame) {
    *
    * @since 1.3.1
    */
-  def fill(valueMap: java.util.Map[String, Any]): DataFrame = fill0(valueMap.toSeq)
+  def fill(valueMap: java.util.Map[String, Any]): DataFrame = fill0(valueMap.asScala.toSeq)
 
   /**
    * (Scala-specific) Returns a new [[DataFrame]] that replaces null values.
@@ -254,7 +254,7 @@ final class DataFrameNaFunctions private[sql](df: DataFrame) {
    * @since 1.3.1
    */
   def replace[T](col: String, replacement: java.util.Map[T, T]): DataFrame = {
-    replace[T](col, replacement.toMap : Map[T, T])
+    replace[T](col, replacement.asScala.toMap)
   }
 
   /**
@@ -277,7 +277,7 @@ final class DataFrameNaFunctions private[sql](df: DataFrame) {
    * @since 1.3.1
    */
   def replace[T](cols: Array[String], replacement: java.util.Map[T, T]): DataFrame = {
-    replace(cols.toSeq, replacement.toMap)
+    replace(cols.toSeq, replacement.asScala.toMap)
   }
 
   /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/DataFrameReader.scala b/sql/core/src/main/scala/org/apache/spark/sql/DataFrameReader.scala
index 6dc7bfe333..97a8b6518a 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/DataFrameReader.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/DataFrameReader.scala
@@ -19,6 +19,8 @@ package org.apache.spark.sql
 
 import java.util.Properties
 
+import scala.collection.JavaConverters._
+
 import org.apache.hadoop.fs.Path
 
 import org.apache.spark.annotation.Experimental
@@ -90,7 +92,7 @@ class DataFrameReader private[sql](sqlContext: SQLContext) extends Logging {
    * @since 1.4.0
    */
   def options(options: java.util.Map[String, String]): DataFrameReader = {
-    this.options(scala.collection.JavaConversions.mapAsScalaMap(options))
+    this.options(options.asScala)
     this
   }
 
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala b/sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala
index ce8744b531..b2a66dd417 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/DataFrameWriter.scala
@@ -19,6 +19,8 @@ package org.apache.spark.sql
 
 import java.util.Properties
 
+import scala.collection.JavaConverters._
+
 import org.apache.spark.annotation.Experimental
 import org.apache.spark.sql.catalyst.{SqlParser, TableIdentifier}
 import org.apache.spark.sql.catalyst.analysis.UnresolvedRelation
@@ -109,7 +111,7 @@ final class DataFrameWriter private[sql](df: DataFrame) {
    * @since 1.4.0
    */
   def options(options: java.util.Map[String, String]): DataFrameWriter = {
-    this.options(scala.collection.JavaConversions.mapAsScalaMap(options))
+    this.options(options.asScala)
     this
   }
 
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/GroupedData.scala b/sql/core/src/main/scala/org/apache/spark/sql/GroupedData.scala
index 99d557b03a..ee31d83cce 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/GroupedData.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/GroupedData.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.language.implicitConversions
 
 import org.apache.spark.annotation.Experimental
@@ -188,7 +188,7 @@ class GroupedData protected[sql](
    * @since 1.3.0
    */
   def agg(exprs: java.util.Map[String, String]): DataFrame = {
-    agg(exprs.toMap)
+    agg(exprs.asScala.toMap)
   }
 
   /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala b/sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala
index e9de14f025..e6f7619519 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/SQLConf.scala
@@ -20,7 +20,7 @@ package org.apache.spark.sql
 import java.util.Properties
 
 import scala.collection.immutable
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.parquet.hadoop.ParquetOutputCommitter
 
@@ -531,7 +531,7 @@ private[sql] class SQLConf extends Serializable with CatalystConf {
 
   /** Set Spark SQL configuration properties. */
   def setConf(props: Properties): Unit = settings.synchronized {
-    props.foreach { case (k, v) => setConfString(k, v) }
+    props.asScala.foreach { case (k, v) => setConfString(k, v) }
   }
 
   /** Set the given Spark SQL configuration property using a `string` value. */
@@ -601,24 +601,25 @@ private[sql] class SQLConf extends Serializable with CatalystConf {
    * Return all the configuration properties that have been set (i.e. not the default).
    * This creates a new copy of the config properties in the form of a Map.
    */
-  def getAllConfs: immutable.Map[String, String] = settings.synchronized { settings.toMap }
+  def getAllConfs: immutable.Map[String, String] =
+    settings.synchronized { settings.asScala.toMap }
 
   /**
    * Return all the configuration definitions that have been defined in [[SQLConf]]. Each
    * definition contains key, defaultValue and doc.
    */
   def getAllDefinedConfs: Seq[(String, String, String)] = sqlConfEntries.synchronized {
-    sqlConfEntries.values.filter(_.isPublic).map { entry =>
+    sqlConfEntries.values.asScala.filter(_.isPublic).map { entry =>
       (entry.key, entry.defaultValueString, entry.doc)
     }.toSeq
   }
 
   private[spark] def unsetConf(key: String): Unit = {
-    settings -= key
+    settings.remove(key)
   }
 
   private[spark] def unsetConf(entry: SQLConfEntry[_]): Unit = {
-    settings -= entry.key
+    settings.remove(entry.key)
   }
 
   private[spark] def clear(): Unit = {
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala b/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
index a1eea09e04..4e8414af50 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
@@ -21,7 +21,7 @@ import java.beans.Introspector
 import java.util.Properties
 import java.util.concurrent.atomic.AtomicReference
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.immutable
 import scala.reflect.runtime.universe.TypeTag
 import scala.util.control.NonFatal
@@ -225,7 +225,7 @@ class SQLContext(@transient val sparkContext: SparkContext)
     conf.setConf(properties)
     // After we have populated SQLConf, we call setConf to populate other confs in the subclass
     // (e.g. hiveconf in HiveContext).
-    properties.foreach {
+    properties.asScala.foreach {
       case (key, value) => setConf(key, value)
     }
   }
@@ -567,7 +567,7 @@ class SQLContext(@transient val sparkContext: SparkContext)
       tableName: String,
       source: String,
       options: java.util.Map[String, String]): DataFrame = {
-    createExternalTable(tableName, source, options.toMap)
+    createExternalTable(tableName, source, options.asScala.toMap)
   }
 
   /**
@@ -612,7 +612,7 @@ class SQLContext(@transient val sparkContext: SparkContext)
       source: String,
       schema: StructType,
       options: java.util.Map[String, String]): DataFrame = {
-    createExternalTable(tableName, source, schema, options.toMap)
+    createExternalTable(tableName, source, schema, options.asScala.toMap)
   }
 
   /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/ResolvedDataSource.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/ResolvedDataSource.scala
index 8fbaf3a305..0117244366 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/ResolvedDataSource.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/ResolvedDataSource.scala
@@ -19,7 +19,7 @@ package org.apache.spark.sql.execution.datasources
 
 import java.util.ServiceLoader
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.language.{existentials, implicitConversions}
 import scala.util.{Success, Failure, Try}
 
@@ -55,7 +55,7 @@ object ResolvedDataSource extends Logging {
     val loader = Utils.getContextOrSparkClassLoader
     val serviceLoader = ServiceLoader.load(classOf[DataSourceRegister], loader)
 
-    serviceLoader.iterator().filter(_.shortName().equalsIgnoreCase(provider)).toList match {
+    serviceLoader.asScala.filter(_.shortName().equalsIgnoreCase(provider)).toList match {
       /** the provider format did not match any given registered aliases */
       case Nil => Try(loader.loadClass(provider)).orElse(Try(loader.loadClass(provider2))) match {
         case Success(dataSource) => dataSource
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystReadSupport.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystReadSupport.scala
index 3f8353af6e..0a6bb44445 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystReadSupport.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystReadSupport.scala
@@ -19,7 +19,7 @@ package org.apache.spark.sql.execution.datasources.parquet
 
 import java.util.{Map => JMap}
 
-import scala.collection.JavaConversions.{iterableAsScalaIterable, mapAsJavaMap, mapAsScalaMap}
+import scala.collection.JavaConverters._
 
 import org.apache.hadoop.conf.Configuration
 import org.apache.parquet.hadoop.api.ReadSupport.ReadContext
@@ -44,7 +44,7 @@ private[parquet] class CatalystReadSupport extends ReadSupport[InternalRow] with
     val parquetRequestedSchema = readContext.getRequestedSchema
 
     val catalystRequestedSchema =
-      Option(readContext.getReadSupportMetadata).map(_.toMap).flatMap { metadata =>
+      Option(readContext.getReadSupportMetadata).map(_.asScala).flatMap { metadata =>
         metadata
           // First tries to read requested schema, which may result from projections
           .get(CatalystReadSupport.SPARK_ROW_REQUESTED_SCHEMA)
@@ -123,7 +123,7 @@ private[parquet] class CatalystReadSupport extends ReadSupport[InternalRow] with
       maybeRequestedSchema.fold(context.getFileSchema) { schemaString =>
         val toParquet = new CatalystSchemaConverter(conf)
         val fileSchema = context.getFileSchema.asGroupType()
-        val fileFieldNames = fileSchema.getFields.map(_.getName).toSet
+        val fileFieldNames = fileSchema.getFields.asScala.map(_.getName).toSet
 
         StructType
           // Deserializes the Catalyst schema of requested columns
@@ -152,7 +152,7 @@ private[parquet] class CatalystReadSupport extends ReadSupport[InternalRow] with
         maybeRequestedSchema.map(CatalystReadSupport.SPARK_ROW_REQUESTED_SCHEMA -> _) ++
         maybeRowSchema.map(RowWriteSupport.SPARK_ROW_SCHEMA -> _)
 
-    new ReadContext(parquetRequestedSchema, metadata)
+    new ReadContext(parquetRequestedSchema, metadata.asJava)
   }
 }
 
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystRowConverter.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystRowConverter.scala
index cbf0704c4a..f682ca0d8f 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystRowConverter.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystRowConverter.scala
@@ -20,7 +20,7 @@ package org.apache.spark.sql.execution.datasources.parquet
 import java.math.{BigDecimal, BigInteger}
 import java.nio.ByteOrder
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 
 import org.apache.parquet.column.Dictionary
@@ -183,7 +183,7 @@ private[parquet] class CatalystRowConverter(
     // those missing fields and create converters for them, although values of these fields are
     // always null.
     val paddedParquetFields = {
-      val parquetFields = parquetType.getFields
+      val parquetFields = parquetType.getFields.asScala
       val parquetFieldNames = parquetFields.map(_.getName).toSet
       val missingFields = catalystType.filterNot(f => parquetFieldNames.contains(f.name))
 
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystSchemaConverter.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystSchemaConverter.scala
index 535f0684e9..be6c0545f5 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystSchemaConverter.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/CatalystSchemaConverter.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.execution.datasources.parquet
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.hadoop.conf.Configuration
 import org.apache.parquet.schema.OriginalType._
@@ -82,7 +82,7 @@ private[parquet] class CatalystSchemaConverter(
   def convert(parquetSchema: MessageType): StructType = convert(parquetSchema.asGroupType())
 
   private def convert(parquetSchema: GroupType): StructType = {
-    val fields = parquetSchema.getFields.map { field =>
+    val fields = parquetSchema.getFields.asScala.map { field =>
       field.getRepetition match {
         case OPTIONAL =>
           StructField(field.getName, convertField(field), nullable = true)
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala
index bbf682aec0..64982f37cf 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetRelation.scala
@@ -21,7 +21,7 @@ import java.net.URI
 import java.util.logging.{Logger => JLogger}
 import java.util.{List => JList}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.util.{Failure, Try}
 
@@ -336,7 +336,7 @@ private[sql] class ParquetRelation(
         override def getPartitions: Array[SparkPartition] = {
           val inputFormat = new ParquetInputFormat[InternalRow] {
             override def listStatus(jobContext: JobContext): JList[FileStatus] = {
-              if (cacheMetadata) cachedStatuses else super.listStatus(jobContext)
+              if (cacheMetadata) cachedStatuses.asJava else super.listStatus(jobContext)
             }
           }
 
@@ -344,7 +344,8 @@ private[sql] class ParquetRelation(
           val rawSplits = inputFormat.getSplits(jobContext)
 
           Array.tabulate[SparkPartition](rawSplits.size) { i =>
-            new SqlNewHadoopPartition(id, i, rawSplits(i).asInstanceOf[InputSplit with Writable])
+            new SqlNewHadoopPartition(
+              id, i, rawSplits.get(i).asInstanceOf[InputSplit with Writable])
           }
         }
       }.asInstanceOf[RDD[Row]]  // type erasure hack to pass RDD[InternalRow] as RDD[Row]
@@ -588,7 +589,7 @@ private[sql] object ParquetRelation extends Logging {
       val metadata = footer.getParquetMetadata.getFileMetaData
       val serializedSchema = metadata
         .getKeyValueMetaData
-        .toMap
+        .asScala.toMap
         .get(CatalystReadSupport.SPARK_METADATA_KEY)
       if (serializedSchema.isEmpty) {
         // Falls back to Parquet schema if no Spark SQL schema found.
@@ -745,7 +746,7 @@ private[sql] object ParquetRelation extends Logging {
           // Reads footers in multi-threaded manner within each task
           val footers =
             ParquetFileReader.readAllFootersInParallel(
-              serializedConf.value, fakeFileStatuses, skipRowGroups)
+              serializedConf.value, fakeFileStatuses.asJava, skipRowGroups).asScala
 
           // Converter used to convert Parquet `MessageType` to Spark SQL `StructType`
           val converter =
@@ -772,7 +773,7 @@ private[sql] object ParquetRelation extends Logging {
     val fileMetaData = footer.getParquetMetadata.getFileMetaData
     fileMetaData
       .getKeyValueMetaData
-      .toMap
+      .asScala.toMap
       .get(CatalystReadSupport.SPARK_METADATA_KEY)
       .flatMap(deserializeSchemaString)
       .getOrElse(converter.convert(fileMetaData.getSchema))
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetTypesConverter.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetTypesConverter.scala
index 42376ef7a9..142301fe87 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetTypesConverter.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetTypesConverter.scala
@@ -18,8 +18,8 @@
 package org.apache.spark.sql.execution.datasources.parquet
 
 import java.io.IOException
+import java.util.{Collections, Arrays}
 
-import scala.collection.JavaConversions._
 import scala.util.Try
 
 import org.apache.hadoop.conf.Configuration
@@ -107,7 +107,7 @@ private[parquet] object ParquetTypesConverter extends Logging {
     ParquetFileWriter.writeMetadataFile(
       conf,
       path,
-      new Footer(path, new ParquetMetadata(metaData, Nil)) :: Nil)
+      Arrays.asList(new Footer(path, new ParquetMetadata(metaData, Collections.emptyList()))))
   }
 
   /**
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/ShuffledHashOuterJoin.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/ShuffledHashOuterJoin.scala
index ed282f98b7..d800c7456b 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/ShuffledHashOuterJoin.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/ShuffledHashOuterJoin.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.execution.joins
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.rdd.RDD
@@ -92,9 +92,9 @@ case class ShuffledHashOuterJoin(
         case FullOuter =>
           // TODO(davies): use UnsafeRow
           val leftHashTable =
-            buildHashTable(leftIter, numLeftRows, newProjection(leftKeys, left.output))
+            buildHashTable(leftIter, numLeftRows, newProjection(leftKeys, left.output)).asScala
           val rightHashTable =
-            buildHashTable(rightIter, numRightRows, newProjection(rightKeys, right.output))
+            buildHashTable(rightIter, numRightRows, newProjection(rightKeys, right.output)).asScala
           (leftHashTable.keySet ++ rightHashTable.keySet).iterator.flatMap { key =>
             fullOuterIterator(key,
               leftHashTable.getOrElse(key, EMPTY_LIST),
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/pythonUDFs.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/pythonUDFs.scala
index 59f8b079ab..5a58d846ad 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/pythonUDFs.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/pythonUDFs.scala
@@ -20,7 +20,7 @@ package org.apache.spark.sql.execution
 import java.io.OutputStream
 import java.util.{List => JList, Map => JMap}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import net.razorvine.pickle._
 
@@ -196,14 +196,15 @@ object EvaluatePython {
     case (c, BinaryType) if c.getClass.isArray && c.getClass.getComponentType.getName == "byte" => c
 
     case (c: java.util.List[_], ArrayType(elementType, _)) =>
-      new GenericArrayData(c.map { e => fromJava(e, elementType)}.toArray)
+      new GenericArrayData(c.asScala.map { e => fromJava(e, elementType)}.toArray)
 
     case (c, ArrayType(elementType, _)) if c.getClass.isArray =>
       new GenericArrayData(c.asInstanceOf[Array[_]].map(e => fromJava(e, elementType)))
 
     case (c: java.util.Map[_, _], MapType(keyType, valueType, _)) =>
-      val keys = c.keysIterator.map(fromJava(_, keyType)).toArray
-      val values = c.valuesIterator.map(fromJava(_, valueType)).toArray
+      val keyValues = c.asScala.toSeq
+      val keys = keyValues.map(kv => fromJava(kv._1, keyType)).toArray
+      val values = keyValues.map(kv => fromJava(kv._2, valueType)).toArray
       ArrayBasedMapData(keys, values)
 
     case (c, StructType(fields)) if c.getClass.isArray =>
@@ -367,7 +368,7 @@ case class BatchPythonEvaluation(udf: PythonUDF, output: Seq[Attribute], child:
       val pickle = new Unpickler
       iter.flatMap { pickedResult =>
         val unpickledBatch = pickle.loads(pickedResult)
-        unpickledBatch.asInstanceOf[java.util.ArrayList[Any]]
+        unpickledBatch.asInstanceOf[java.util.ArrayList[Any]].asScala
       }
     }.mapPartitions { iter =>
       val row = new GenericMutableRow(1)
diff --git a/sql/core/src/test/java/test/org/apache/spark/sql/JavaDataFrameSuite.java b/sql/core/src/test/java/test/org/apache/spark/sql/JavaDataFrameSuite.java
index 7abdd3db80..4867cebf53 100644
--- a/sql/core/src/test/java/test/org/apache/spark/sql/JavaDataFrameSuite.java
+++ b/sql/core/src/test/java/test/org/apache/spark/sql/JavaDataFrameSuite.java
@@ -23,7 +23,7 @@ import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 
-import scala.collection.JavaConversions;
+import scala.collection.JavaConverters;
 import scala.collection.Seq;
 
 import com.google.common.collect.ImmutableMap;
@@ -96,7 +96,7 @@ public class JavaDataFrameSuite {
     df.groupBy().agg(countDistinct("key", "value"));
     df.groupBy().agg(countDistinct(col("key"), col("value")));
     df.select(coalesce(col("key")));
-    
+
     // Varargs with mathfunctions
     DataFrame df2 = context.table("testData2");
     df2.select(exp("a"), exp("b"));
@@ -172,7 +172,7 @@ public class JavaDataFrameSuite {
     Seq<Integer> outputBuffer = (Seq<Integer>) first.getJavaMap(2).get("hello");
     Assert.assertArrayEquals(
       bean.getC().get("hello"),
-      Ints.toArray(JavaConversions.seqAsJavaList(outputBuffer)));
+      Ints.toArray(JavaConverters.seqAsJavaListConverter(outputBuffer).asJava()));
     Seq<String> d = first.getAs(3);
     Assert.assertEquals(bean.getD().size(), d.length());
     for (int i = 0; i < d.length(); i++) {
@@ -206,7 +206,7 @@ public class JavaDataFrameSuite {
       count++;
     }
   }
-  
+
   @Test
   public void testFrequentItems() {
     DataFrame df = context.table("testData2");
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameNaFunctionsSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameNaFunctionsSuite.scala
index cdaa14ac80..329ffb6608 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/DataFrameNaFunctionsSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/DataFrameNaFunctionsSuite.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.sql.test.SharedSQLContext
 
@@ -153,11 +153,11 @@ class DataFrameNaFunctionsSuite extends QueryTest with SharedSQLContext {
 
     // Test Java version
     checkAnswer(
-      df.na.fill(mapAsJavaMap(Map(
+      df.na.fill(Map(
         "a" -> "test",
         "c" -> 1,
         "d" -> 2.2
-      ))),
+      ).asJava),
       Row("test", null, 1, 2.2))
   }
 
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala b/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala
index 4adcefb7dc..3649c2a97b 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala
@@ -19,7 +19,7 @@ package org.apache.spark.sql
 
 import java.util.{Locale, TimeZone}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.sql.catalyst.plans._
 import org.apache.spark.sql.catalyst.util._
@@ -145,7 +145,7 @@ object QueryTest {
   }
 
   def checkAnswer(df: DataFrame, expectedAnswer: java.util.List[Row]): String = {
-    checkAnswer(df, expectedAnswer.toSeq) match {
+    checkAnswer(df, expectedAnswer.asScala) match {
       case Some(errorMessage) => errorMessage
       case None => null
     }
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetAvroCompatibilitySuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetAvroCompatibilitySuite.scala
index 45db619567..bd7cf8c10a 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetAvroCompatibilitySuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetAvroCompatibilitySuite.scala
@@ -20,8 +20,7 @@ package org.apache.spark.sql.execution.datasources.parquet
 import java.nio.ByteBuffer
 import java.util.{List => JList, Map => JMap}
 
-import scala.collection.JavaConverters.seqAsJavaListConverter
-import scala.collection.JavaConverters.mapAsJavaMapConverter
+import scala.collection.JavaConverters._
 
 import org.apache.avro.Schema
 import org.apache.avro.generic.IndexedRecord
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetCompatibilityTest.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetCompatibilityTest.scala
index d85c564e3e..df68432fae 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetCompatibilityTest.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetCompatibilityTest.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.execution.datasources.parquet
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.hadoop.fs.{Path, PathFilter}
 import org.apache.parquet.hadoop.ParquetFileReader
@@ -40,8 +40,9 @@ private[sql] abstract class ParquetCompatibilityTest extends QueryTest with Parq
       override def accept(path: Path): Boolean = pathFilter(path)
     }).toSeq
 
-    val footers = ParquetFileReader.readAllFootersInParallel(configuration, parquetFiles, true)
-    footers.head.getParquetMetadata.getFileMetaData.getSchema
+    val footers =
+      ParquetFileReader.readAllFootersInParallel(configuration, parquetFiles.asJava, true)
+    footers.iterator().next().getParquetMetadata.getFileMetaData.getSchema
   }
 
   protected def logParquetSchema(path: String): Unit = {
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetIOSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetIOSuite.scala
index e6b0a2ea95..08d2b9dee9 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetIOSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetIOSuite.scala
@@ -17,7 +17,9 @@
 
 package org.apache.spark.sql.execution.datasources.parquet
 
-import scala.collection.JavaConversions._
+import java.util.Collections
+
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 import scala.reflect.runtime.universe.TypeTag
 
@@ -28,7 +30,7 @@ import org.apache.parquet.example.data.simple.SimpleGroup
 import org.apache.parquet.example.data.{Group, GroupWriter}
 import org.apache.parquet.hadoop.api.WriteSupport
 import org.apache.parquet.hadoop.api.WriteSupport.WriteContext
-import org.apache.parquet.hadoop.metadata.{CompressionCodecName, FileMetaData, ParquetMetadata}
+import org.apache.parquet.hadoop.metadata.{BlockMetaData, CompressionCodecName, FileMetaData, ParquetMetadata}
 import org.apache.parquet.hadoop.{Footer, ParquetFileWriter, ParquetOutputCommitter, ParquetWriter}
 import org.apache.parquet.io.api.RecordConsumer
 import org.apache.parquet.schema.{MessageType, MessageTypeParser}
@@ -205,9 +207,8 @@ class ParquetIOSuite extends QueryTest with ParquetTest with SharedSQLContext {
   test("compression codec") {
     def compressionCodecFor(path: String): String = {
       val codecs = ParquetTypesConverter
-        .readMetaData(new Path(path), Some(configuration))
-        .getBlocks
-        .flatMap(_.getColumns)
+        .readMetaData(new Path(path), Some(configuration)).getBlocks.asScala
+        .flatMap(_.getColumns.asScala)
         .map(_.getCodec.name())
         .distinct
 
@@ -348,14 +349,16 @@ class ParquetIOSuite extends QueryTest with ParquetTest with SharedSQLContext {
       """.stripMargin)
 
     withTempPath { location =>
-      val extraMetadata = Map(CatalystReadSupport.SPARK_METADATA_KEY -> sparkSchema.toString)
+      val extraMetadata = Collections.singletonMap(
+        CatalystReadSupport.SPARK_METADATA_KEY, sparkSchema.toString)
       val fileMetadata = new FileMetaData(parquetSchema, extraMetadata, "Spark")
       val path = new Path(location.getCanonicalPath)
 
       ParquetFileWriter.writeMetadataFile(
         sqlContext.sparkContext.hadoopConfiguration,
         path,
-        new Footer(path, new ParquetMetadata(fileMetadata, Nil)) :: Nil)
+        Collections.singletonList(
+          new Footer(path, new ParquetMetadata(fileMetadata, Collections.emptyList()))))
 
       assertResult(sqlContext.read.parquet(path.toString).schema) {
         StructType(
@@ -386,7 +389,7 @@ class ParquetIOSuite extends QueryTest with ParquetTest with SharedSQLContext {
     } finally {
       // Hadoop 1 doesn't have `Configuration.unset`
       configuration.clear()
-      clonedConf.foreach(entry => configuration.set(entry.getKey, entry.getValue))
+      clonedConf.asScala.foreach(entry => configuration.set(entry.getKey, entry.getValue))
     }
   }
 
@@ -410,7 +413,7 @@ class ParquetIOSuite extends QueryTest with ParquetTest with SharedSQLContext {
     } finally {
       // Hadoop 1 doesn't have `Configuration.unset`
       configuration.clear()
-      clonedConf.foreach(entry => configuration.set(entry.getKey, entry.getValue))
+      clonedConf.asScala.foreach(entry => configuration.set(entry.getKey, entry.getValue))
     }
   }
 
@@ -434,7 +437,7 @@ class ParquetIOSuite extends QueryTest with ParquetTest with SharedSQLContext {
       } finally {
         // Hadoop 1 doesn't have `Configuration.unset`
         configuration.clear()
-        clonedConf.foreach(entry => configuration.set(entry.getKey, entry.getValue))
+        clonedConf.asScala.foreach(entry => configuration.set(entry.getKey, entry.getValue))
       }
     }
   }
@@ -481,7 +484,7 @@ class ParquetIOSuite extends QueryTest with ParquetTest with SharedSQLContext {
     } finally {
       // Hadoop 1 doesn't have `Configuration.unset`
       configuration.clear()
-      clonedConf.foreach(entry => configuration.set(entry.getKey, entry.getValue))
+      clonedConf.asScala.foreach(entry => configuration.set(entry.getKey, entry.getValue))
     }
   }
 }
diff --git a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkExecuteStatementOperation.scala b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkExecuteStatementOperation.scala
index 02cc7e5efa..306f98bcb5 100644
--- a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkExecuteStatementOperation.scala
+++ b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkExecuteStatementOperation.scala
@@ -20,9 +20,9 @@ package org.apache.spark.sql.hive.thriftserver
 import java.security.PrivilegedExceptionAction
 import java.sql.{Date, Timestamp}
 import java.util.concurrent.RejectedExecutionException
-import java.util.{Map => JMap, UUID}
+import java.util.{Arrays, Map => JMap, UUID}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{ArrayBuffer, Map => SMap}
 import scala.util.control.NonFatal
 
@@ -126,13 +126,13 @@ private[hive] class SparkExecuteStatementOperation(
 
   def getResultSetSchema: TableSchema = {
     if (result == null || result.queryExecution.analyzed.output.size == 0) {
-      new TableSchema(new FieldSchema("Result", "string", "") :: Nil)
+      new TableSchema(Arrays.asList(new FieldSchema("Result", "string", "")))
     } else {
       logInfo(s"Result Schema: ${result.queryExecution.analyzed.output}")
       val schema = result.queryExecution.analyzed.output.map { attr =>
         new FieldSchema(attr.name, HiveMetastoreTypes.toMetastoreType(attr.dataType), "")
       }
-      new TableSchema(schema)
+      new TableSchema(schema.asJava)
     }
   }
 
@@ -298,7 +298,7 @@ private[hive] class SparkExecuteStatementOperation(
       sqlOperationConf = new HiveConf(sqlOperationConf)
 
       // apply overlay query specific settings, if any
-      getConfOverlay().foreach { case (k, v) =>
+      getConfOverlay().asScala.foreach { case (k, v) =>
         try {
           sqlOperationConf.verifyAndSet(k, v)
         } catch {
diff --git a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIDriver.scala b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIDriver.scala
index 7799704c81..a29df56798 100644
--- a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIDriver.scala
+++ b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIDriver.scala
@@ -17,11 +17,11 @@
 
 package org.apache.spark.sql.hive.thriftserver
 
-import scala.collection.JavaConversions._
-
 import java.io._
 import java.util.{ArrayList => JArrayList, Locale}
 
+import scala.collection.JavaConverters._
+
 import jline.console.ConsoleReader
 import jline.console.history.FileHistory
 
@@ -101,9 +101,9 @@ private[hive] object SparkSQLCLIDriver extends Logging {
 
     // Set all properties specified via command line.
     val conf: HiveConf = sessionState.getConf
-    sessionState.cmdProperties.entrySet().foreach { item =>
-      val key = item.getKey.asInstanceOf[String]
-      val value = item.getValue.asInstanceOf[String]
+    sessionState.cmdProperties.entrySet().asScala.foreach { item =>
+      val key = item.getKey.toString
+      val value = item.getValue.toString
       // We do not propagate metastore options to the execution copy of hive.
       if (key != "javax.jdo.option.ConnectionURL") {
         conf.set(key, value)
@@ -316,15 +316,15 @@ private[hive] class SparkSQLCLIDriver extends CliDriver with Logging {
 
           if (HiveConf.getBoolVar(conf, HiveConf.ConfVars.HIVE_CLI_PRINT_HEADER)) {
             // Print the column names.
-            Option(driver.getSchema.getFieldSchemas).map { fields =>
-              out.println(fields.map(_.getName).mkString("\t"))
+            Option(driver.getSchema.getFieldSchemas).foreach { fields =>
+              out.println(fields.asScala.map(_.getName).mkString("\t"))
             }
           }
 
           var counter = 0
           try {
             while (!out.checkError() && driver.getResults(res)) {
-              res.foreach{ l =>
+              res.asScala.foreach { l =>
                 counter += 1
                 out.println(l)
               }
diff --git a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIService.scala b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIService.scala
index 644165acf7..5ad8c54f29 100644
--- a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIService.scala
+++ b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLCLIService.scala
@@ -21,6 +21,8 @@ import java.io.IOException
 import java.util.{List => JList}
 import javax.security.auth.login.LoginException
 
+import scala.collection.JavaConverters._
+
 import org.apache.commons.logging.Log
 import org.apache.hadoop.hive.conf.HiveConf
 import org.apache.hadoop.hive.shims.Utils
@@ -34,8 +36,6 @@ import org.apache.hive.service.{AbstractService, Service, ServiceException}
 import org.apache.spark.sql.hive.HiveContext
 import org.apache.spark.sql.hive.thriftserver.ReflectionUtils._
 
-import scala.collection.JavaConversions._
-
 private[hive] class SparkSQLCLIService(hiveServer: HiveServer2, hiveContext: HiveContext)
   extends CLIService(hiveServer)
   with ReflectedCompositeService {
@@ -76,7 +76,7 @@ private[thriftserver] trait ReflectedCompositeService { this: AbstractService =>
   def initCompositeService(hiveConf: HiveConf) {
     // Emulating `CompositeService.init(hiveConf)`
     val serviceList = getAncestorField[JList[Service]](this, 2, "serviceList")
-    serviceList.foreach(_.init(hiveConf))
+    serviceList.asScala.foreach(_.init(hiveConf))
 
     // Emulating `AbstractService.init(hiveConf)`
     invoke(classOf[AbstractService], this, "ensureCurrentState", classOf[STATE] -> STATE.NOTINITED)
diff --git a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLDriver.scala b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLDriver.scala
index 77272aecf2..2619286afc 100644
--- a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLDriver.scala
+++ b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLDriver.scala
@@ -17,7 +17,9 @@
 
 package org.apache.spark.sql.hive.thriftserver
 
-import java.util.{ArrayList => JArrayList, List => JList}
+import java.util.{Arrays, ArrayList => JArrayList, List => JList}
+
+import scala.collection.JavaConverters._
 
 import org.apache.commons.lang3.exception.ExceptionUtils
 import org.apache.hadoop.hive.metastore.api.{FieldSchema, Schema}
@@ -27,8 +29,6 @@ import org.apache.hadoop.hive.ql.processors.CommandProcessorResponse
 import org.apache.spark.Logging
 import org.apache.spark.sql.hive.{HiveContext, HiveMetastoreTypes}
 
-import scala.collection.JavaConversions._
-
 private[hive] class SparkSQLDriver(
     val context: HiveContext = SparkSQLEnv.hiveContext)
   extends Driver
@@ -43,14 +43,14 @@ private[hive] class SparkSQLDriver(
   private def getResultSetSchema(query: context.QueryExecution): Schema = {
     val analyzed = query.analyzed
     logDebug(s"Result Schema: ${analyzed.output}")
-    if (analyzed.output.size == 0) {
-      new Schema(new FieldSchema("Response code", "string", "") :: Nil, null)
+    if (analyzed.output.isEmpty) {
+      new Schema(Arrays.asList(new FieldSchema("Response code", "string", "")), null)
     } else {
       val fieldSchemas = analyzed.output.map { attr =>
         new FieldSchema(attr.name, HiveMetastoreTypes.toMetastoreType(attr.dataType), "")
       }
 
-      new Schema(fieldSchemas, null)
+      new Schema(fieldSchemas.asJava, null)
     }
   }
 
@@ -79,7 +79,7 @@ private[hive] class SparkSQLDriver(
     if (hiveResponse == null) {
       false
     } else {
-      res.asInstanceOf[JArrayList[String]].addAll(hiveResponse)
+      res.asInstanceOf[JArrayList[String]].addAll(hiveResponse.asJava)
       hiveResponse = null
       true
     }
diff --git a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLEnv.scala b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLEnv.scala
index 1d41c46131..bacf6cc458 100644
--- a/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLEnv.scala
+++ b/sql/hive-thriftserver/src/main/scala/org/apache/spark/sql/hive/thriftserver/SparkSQLEnv.scala
@@ -19,7 +19,7 @@ package org.apache.spark.sql.hive.thriftserver
 
 import java.io.PrintStream
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.scheduler.StatsReportListener
 import org.apache.spark.sql.hive.HiveContext
@@ -64,7 +64,7 @@ private[hive] object SparkSQLEnv extends Logging {
       hiveContext.setConf("spark.sql.hive.version", HiveContext.hiveExecutionVersion)
 
       if (log.isDebugEnabled) {
-        hiveContext.hiveconf.getAllProperties.toSeq.sorted.foreach { case (k, v) =>
+        hiveContext.hiveconf.getAllProperties.asScala.toSeq.sorted.foreach { case (k, v) =>
           logDebug(s"HiveConf var: $k=$v")
         }
       }
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
index 17cc83087f..c0a458fa9a 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveContext.scala
@@ -22,7 +22,7 @@ import java.net.{URL, URLClassLoader}
 import java.sql.Timestamp
 import java.util.concurrent.TimeUnit
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.HashMap
 import scala.language.implicitConversions
 import scala.concurrent.duration._
@@ -194,7 +194,7 @@ class HiveContext(sc: SparkContext) extends SQLContext(sc) with Logging {
     logInfo("defalt warehouse location is " + defaltWarehouseLocation)
 
     // `configure` goes second to override other settings.
-    val allConfig = metadataConf.iterator.map(e => e.getKey -> e.getValue).toMap ++ configure
+    val allConfig = metadataConf.asScala.map(e => e.getKey -> e.getValue).toMap ++ configure
 
     val isolatedLoader = if (hiveMetastoreJars == "builtin") {
       if (hiveExecutionVersion != hiveMetastoreVersion) {
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveInspectors.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveInspectors.scala
index 64fffdbf9b..cfe2bb05ad 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveInspectors.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveInspectors.scala
@@ -17,6 +17,8 @@
 
 package org.apache.spark.sql.hive
 
+import scala.collection.JavaConverters._
+
 import org.apache.hadoop.hive.common.`type`.{HiveDecimal, HiveVarchar}
 import org.apache.hadoop.hive.serde2.objectinspector.primitive._
 import org.apache.hadoop.hive.serde2.objectinspector.{StructField => HiveStructField, _}
@@ -31,9 +33,6 @@ import org.apache.spark.sql.types._
 import org.apache.spark.sql.{AnalysisException, types}
 import org.apache.spark.unsafe.types.UTF8String
 
-/* Implicit conversions */
-import scala.collection.JavaConversions._
-
 /**
  * 1. The Underlying data type in catalyst and in Hive
  * In catalyst:
@@ -290,13 +289,13 @@ private[hive] trait HiveInspectors {
       DateTimeUtils.fromJavaDate(poi.getWritableConstantValue.get())
     case mi: StandardConstantMapObjectInspector =>
       // take the value from the map inspector object, rather than the input data
-      val map = mi.getWritableConstantValue
-      val keys = map.keysIterator.map(unwrap(_, mi.getMapKeyObjectInspector)).toArray
-      val values = map.valuesIterator.map(unwrap(_, mi.getMapValueObjectInspector)).toArray
+      val keyValues = mi.getWritableConstantValue.asScala.toSeq
+      val keys = keyValues.map(kv => unwrap(kv._1, mi.getMapKeyObjectInspector)).toArray
+      val values = keyValues.map(kv => unwrap(kv._2, mi.getMapValueObjectInspector)).toArray
       ArrayBasedMapData(keys, values)
     case li: StandardConstantListObjectInspector =>
       // take the value from the list inspector object, rather than the input data
-      val values = li.getWritableConstantValue
+      val values = li.getWritableConstantValue.asScala
         .map(unwrap(_, li.getListElementObjectInspector))
         .toArray
       new GenericArrayData(values)
@@ -342,7 +341,7 @@ private[hive] trait HiveInspectors {
     case li: ListObjectInspector =>
       Option(li.getList(data))
         .map { l =>
-          val values = l.map(unwrap(_, li.getListElementObjectInspector)).toArray
+          val values = l.asScala.map(unwrap(_, li.getListElementObjectInspector)).toArray
           new GenericArrayData(values)
         }
         .orNull
@@ -351,15 +350,16 @@ private[hive] trait HiveInspectors {
       if (map == null) {
         null
       } else {
-        val keys = map.keysIterator.map(unwrap(_, mi.getMapKeyObjectInspector)).toArray
-        val values = map.valuesIterator.map(unwrap(_, mi.getMapValueObjectInspector)).toArray
+        val keyValues = map.asScala.toSeq
+        val keys = keyValues.map(kv => unwrap(kv._1, mi.getMapKeyObjectInspector)).toArray
+        val values = keyValues.map(kv => unwrap(kv._2, mi.getMapValueObjectInspector)).toArray
         ArrayBasedMapData(keys, values)
       }
     // currently, hive doesn't provide the ConstantStructObjectInspector
     case si: StructObjectInspector =>
       val allRefs = si.getAllStructFieldRefs
-      InternalRow.fromSeq(
-        allRefs.map(r => unwrap(si.getStructFieldData(data, r), r.getFieldObjectInspector)))
+      InternalRow.fromSeq(allRefs.asScala.map(
+        r => unwrap(si.getStructFieldData(data, r), r.getFieldObjectInspector)))
   }
 
 
@@ -403,14 +403,14 @@ private[hive] trait HiveInspectors {
 
     case soi: StandardStructObjectInspector =>
       val schema = dataType.asInstanceOf[StructType]
-      val wrappers = soi.getAllStructFieldRefs.zip(schema.fields).map { case (ref, field) =>
-        wrapperFor(ref.getFieldObjectInspector, field.dataType)
+      val wrappers = soi.getAllStructFieldRefs.asScala.zip(schema.fields).map {
+        case (ref, field) => wrapperFor(ref.getFieldObjectInspector, field.dataType)
       }
       (o: Any) => {
         if (o != null) {
           val struct = soi.create()
           val row = o.asInstanceOf[InternalRow]
-          soi.getAllStructFieldRefs.zip(wrappers).zipWithIndex.foreach {
+          soi.getAllStructFieldRefs.asScala.zip(wrappers).zipWithIndex.foreach {
             case ((field, wrapper), i) =>
               soi.setStructFieldData(struct, field, wrapper(row.get(i, schema(i).dataType)))
           }
@@ -537,7 +537,7 @@ private[hive] trait HiveInspectors {
       // 1. create the pojo (most likely) object
       val result = x.create()
       var i = 0
-      while (i < fieldRefs.length) {
+      while (i < fieldRefs.size) {
         // 2. set the property for the pojo
         val tpe = structType(i).dataType
         x.setStructFieldData(
@@ -552,9 +552,9 @@ private[hive] trait HiveInspectors {
       val fieldRefs = x.getAllStructFieldRefs
       val structType = dataType.asInstanceOf[StructType]
       val row = a.asInstanceOf[InternalRow]
-      val result = new java.util.ArrayList[AnyRef](fieldRefs.length)
+      val result = new java.util.ArrayList[AnyRef](fieldRefs.size)
       var i = 0
-      while (i < fieldRefs.length) {
+      while (i < fieldRefs.size) {
         val tpe = structType(i).dataType
         result.add(wrap(row.get(i, tpe), fieldRefs.get(i).getFieldObjectInspector, tpe))
         i += 1
@@ -712,10 +712,10 @@ private[hive] trait HiveInspectors {
 
   def inspectorToDataType(inspector: ObjectInspector): DataType = inspector match {
     case s: StructObjectInspector =>
-      StructType(s.getAllStructFieldRefs.map(f => {
+      StructType(s.getAllStructFieldRefs.asScala.map(f =>
         types.StructField(
           f.getFieldName, inspectorToDataType(f.getFieldObjectInspector), nullable = true)
-      }))
+      ))
     case l: ListObjectInspector => ArrayType(inspectorToDataType(l.getListElementObjectInspector))
     case m: MapObjectInspector =>
       MapType(
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
index 98d21aa76d..b8da0840ae 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveMetastoreCatalog.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.hive
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 
 import com.google.common.base.Objects
@@ -483,7 +483,7 @@ private[hive] class HiveMetastoreCatalog(val client: ClientInterface, hive: Hive
       // are empty.
       val partitions = metastoreRelation.getHiveQlPartitions().map { p =>
         val location = p.getLocation
-        val values = InternalRow.fromSeq(p.getValues.zip(partitionColumnDataTypes).map {
+        val values = InternalRow.fromSeq(p.getValues.asScala.zip(partitionColumnDataTypes).map {
           case (rawValue, dataType) => Cast(Literal(rawValue), dataType).eval(null)
         })
         ParquetPartition(values, location)
@@ -798,9 +798,9 @@ private[hive] case class MetastoreRelation
 
     val sd = new org.apache.hadoop.hive.metastore.api.StorageDescriptor()
     tTable.setSd(sd)
-    sd.setCols(table.schema.map(c => new FieldSchema(c.name, c.hiveType, c.comment)))
+    sd.setCols(table.schema.map(c => new FieldSchema(c.name, c.hiveType, c.comment)).asJava)
     tTable.setPartitionKeys(
-      table.partitionColumns.map(c => new FieldSchema(c.name, c.hiveType, c.comment)))
+      table.partitionColumns.map(c => new FieldSchema(c.name, c.hiveType, c.comment)).asJava)
 
     table.location.foreach(sd.setLocation)
     table.inputFormat.foreach(sd.setInputFormat)
@@ -852,11 +852,11 @@ private[hive] case class MetastoreRelation
       val tPartition = new org.apache.hadoop.hive.metastore.api.Partition
       tPartition.setDbName(databaseName)
       tPartition.setTableName(tableName)
-      tPartition.setValues(p.values)
+      tPartition.setValues(p.values.asJava)
 
       val sd = new org.apache.hadoop.hive.metastore.api.StorageDescriptor()
       tPartition.setSd(sd)
-      sd.setCols(table.schema.map(c => new FieldSchema(c.name, c.hiveType, c.comment)))
+      sd.setCols(table.schema.map(c => new FieldSchema(c.name, c.hiveType, c.comment)).asJava)
 
       sd.setLocation(p.storage.location)
       sd.setInputFormat(p.storage.inputFormat)
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
index ad33dee555..d5cd7e98b5 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveQl.scala
@@ -20,6 +20,9 @@ package org.apache.spark.sql.hive
 import java.sql.Date
 import java.util.Locale
 
+import scala.collection.JavaConverters._
+import scala.collection.mutable.ArrayBuffer
+
 import org.apache.hadoop.hive.conf.HiveConf
 import org.apache.hadoop.hive.conf.HiveConf.ConfVars
 import org.apache.hadoop.hive.serde.serdeConstants
@@ -48,10 +51,6 @@ import org.apache.spark.sql.types._
 import org.apache.spark.unsafe.types.CalendarInterval
 import org.apache.spark.util.random.RandomSampler
 
-/* Implicit conversions */
-import scala.collection.JavaConversions._
-import scala.collection.mutable.ArrayBuffer
-
 /**
  * Used when we need to start parsing the AST before deciding that we are going to pass the command
  * back for Hive to execute natively.  Will be replaced with a native command that contains the
@@ -202,7 +201,7 @@ private[hive] object HiveQl extends Logging {
      * Returns a scala.Seq equivalent to [s] or Nil if [s] is null.
      */
     private def nilIfEmpty[A](s: java.util.List[A]): Seq[A] =
-      Option(s).map(_.toSeq).getOrElse(Nil)
+      Option(s).map(_.asScala).getOrElse(Nil)
 
     /**
      * Returns this ASTNode with the text changed to `newText`.
@@ -217,7 +216,7 @@ private[hive] object HiveQl extends Logging {
      */
     def withChildren(newChildren: Seq[ASTNode]): ASTNode = {
       (1 to n.getChildCount).foreach(_ => n.deleteChild(0))
-      n.addChildren(newChildren)
+      n.addChildren(newChildren.asJava)
       n
     }
 
@@ -323,11 +322,11 @@ private[hive] object HiveQl extends Logging {
     assert(tree.asInstanceOf[ASTNode].getText == "TOK_CREATETABLE", "Only CREATE TABLE supported.")
     val tableOps = tree.getChildren
     val colList =
-      tableOps
+      tableOps.asScala
         .find(_.asInstanceOf[ASTNode].getText == "TOK_TABCOLLIST")
         .getOrElse(sys.error("No columnList!")).getChildren
 
-    colList.map(nodeToAttribute)
+    colList.asScala.map(nodeToAttribute)
   }
 
   /** Extractor for matching Hive's AST Tokens. */
@@ -337,7 +336,7 @@ private[hive] object HiveQl extends Logging {
       case t: ASTNode =>
         CurrentOrigin.setPosition(t.getLine, t.getCharPositionInLine)
         Some((t.getText,
-          Option(t.getChildren).map(_.toList).getOrElse(Nil).asInstanceOf[Seq[ASTNode]]))
+          Option(t.getChildren).map(_.asScala.toList).getOrElse(Nil).asInstanceOf[Seq[ASTNode]]))
       case _ => None
     }
   }
@@ -424,7 +423,9 @@ private[hive] object HiveQl extends Logging {
 
   protected def extractDbNameTableName(tableNameParts: Node): (Option[String], String) = {
     val (db, tableName) =
-      tableNameParts.getChildren.map { case Token(part, Nil) => cleanIdentifier(part) } match {
+      tableNameParts.getChildren.asScala.map {
+        case Token(part, Nil) => cleanIdentifier(part)
+      } match {
         case Seq(tableOnly) => (None, tableOnly)
         case Seq(databaseName, table) => (Some(databaseName), table)
       }
@@ -433,7 +434,9 @@ private[hive] object HiveQl extends Logging {
   }
 
   protected def extractTableIdent(tableNameParts: Node): Seq[String] = {
-    tableNameParts.getChildren.map { case Token(part, Nil) => cleanIdentifier(part) } match {
+    tableNameParts.getChildren.asScala.map {
+      case Token(part, Nil) => cleanIdentifier(part)
+    } match {
       case Seq(tableOnly) => Seq(tableOnly)
       case Seq(databaseName, table) => Seq(databaseName, table)
       case other => sys.error("Hive only supports tables names like 'tableName' " +
@@ -624,7 +627,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
           val cols = BaseSemanticAnalyzer.getColumns(list, true)
           if (cols != null) {
             tableDesc = tableDesc.copy(
-              schema = cols.map { field =>
+              schema = cols.asScala.map { field =>
                 HiveColumn(field.getName, field.getType, field.getComment)
               })
           }
@@ -636,7 +639,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
           val cols = BaseSemanticAnalyzer.getColumns(list(0), false)
           if (cols != null) {
             tableDesc = tableDesc.copy(
-              partitionColumns = cols.map { field =>
+              partitionColumns = cols.asScala.map { field =>
                 HiveColumn(field.getName, field.getType, field.getComment)
               })
           }
@@ -672,7 +675,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
             case _ => assert(false)
           }
           tableDesc = tableDesc.copy(
-            serdeProperties = tableDesc.serdeProperties ++ serdeParams)
+            serdeProperties = tableDesc.serdeProperties ++ serdeParams.asScala)
         case Token("TOK_TABLELOCATION", child :: Nil) =>
           var location = BaseSemanticAnalyzer.unescapeSQLString(child.getText)
           location = EximUtil.relativeToAbsolutePath(hiveConf, location)
@@ -684,7 +687,8 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
             val serdeParams = new java.util.HashMap[String, String]()
             BaseSemanticAnalyzer.readProps(
               (child.getChild(1).getChild(0)).asInstanceOf[ASTNode], serdeParams)
-            tableDesc = tableDesc.copy(serdeProperties = tableDesc.serdeProperties ++ serdeParams)
+            tableDesc = tableDesc.copy(
+              serdeProperties = tableDesc.serdeProperties ++ serdeParams.asScala)
           }
         case Token("TOK_FILEFORMAT_GENERIC", child :: Nil) =>
           child.getText().toLowerCase(Locale.ENGLISH) match {
@@ -847,7 +851,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
         }
 
         val withWhere = whereClause.map { whereNode =>
-          val Seq(whereExpr) = whereNode.getChildren.toSeq
+          val Seq(whereExpr) = whereNode.getChildren.asScala
           Filter(nodeToExpr(whereExpr), relations)
         }.getOrElse(relations)
 
@@ -856,7 +860,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
 
         // Script transformations are expressed as a select clause with a single expression of type
         // TOK_TRANSFORM
-        val transformation = select.getChildren.head match {
+        val transformation = select.getChildren.iterator().next() match {
           case Token("TOK_SELEXPR",
                  Token("TOK_TRANSFORM",
                    Token("TOK_EXPLIST", inputExprs) ::
@@ -925,10 +929,10 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
 
         val withLateralView = lateralViewClause.map { lv =>
           val Token("TOK_SELECT",
-          Token("TOK_SELEXPR", clauses) :: Nil) = lv.getChildren.head
+          Token("TOK_SELEXPR", clauses) :: Nil) = lv.getChildren.iterator().next()
 
-          val alias =
-            getClause("TOK_TABALIAS", clauses).getChildren.head.asInstanceOf[ASTNode].getText
+          val alias = getClause("TOK_TABALIAS", clauses).getChildren.iterator().next()
+            .asInstanceOf[ASTNode].getText
 
           val (generator, attributes) = nodesToGenerator(clauses)
             Generate(
@@ -944,7 +948,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
         // (if there is a group by) or a script transformation.
         val withProject: LogicalPlan = transformation.getOrElse {
           val selectExpressions =
-            select.getChildren.flatMap(selExprNodeToExpr).map(UnresolvedAlias(_)).toSeq
+            select.getChildren.asScala.flatMap(selExprNodeToExpr).map(UnresolvedAlias)
           Seq(
             groupByClause.map(e => e match {
               case Token("TOK_GROUPBY", children) =>
@@ -973,7 +977,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
 
         // Handle HAVING clause.
         val withHaving = havingClause.map { h =>
-          val havingExpr = h.getChildren.toSeq match { case Seq(hexpr) => nodeToExpr(hexpr) }
+          val havingExpr = h.getChildren.asScala match { case Seq(hexpr) => nodeToExpr(hexpr) }
           // Note that we added a cast to boolean. If the expression itself is already boolean,
           // the optimizer will get rid of the unnecessary cast.
           Filter(Cast(havingExpr, BooleanType), withProject)
@@ -983,32 +987,42 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
         val withDistinct =
           if (selectDistinctClause.isDefined) Distinct(withHaving) else withHaving
 
-        // Handle ORDER BY, SORT BY, DISTRIBETU BY, and CLUSTER BY clause.
+        // Handle ORDER BY, SORT BY, DISTRIBUTE BY, and CLUSTER BY clause.
         val withSort =
           (orderByClause, sortByClause, distributeByClause, clusterByClause) match {
             case (Some(totalOrdering), None, None, None) =>
-              Sort(totalOrdering.getChildren.map(nodeToSortOrder), true, withDistinct)
+              Sort(totalOrdering.getChildren.asScala.map(nodeToSortOrder), true, withDistinct)
             case (None, Some(perPartitionOrdering), None, None) =>
-              Sort(perPartitionOrdering.getChildren.map(nodeToSortOrder), false, withDistinct)
+              Sort(
+                perPartitionOrdering.getChildren.asScala.map(nodeToSortOrder),
+                false, withDistinct)
             case (None, None, Some(partitionExprs), None) =>
-              RepartitionByExpression(partitionExprs.getChildren.map(nodeToExpr), withDistinct)
+              RepartitionByExpression(
+                partitionExprs.getChildren.asScala.map(nodeToExpr), withDistinct)
             case (None, Some(perPartitionOrdering), Some(partitionExprs), None) =>
-              Sort(perPartitionOrdering.getChildren.map(nodeToSortOrder), false,
-                RepartitionByExpression(partitionExprs.getChildren.map(nodeToExpr), withDistinct))
+              Sort(
+                perPartitionOrdering.getChildren.asScala.map(nodeToSortOrder), false,
+                RepartitionByExpression(
+                  partitionExprs.getChildren.asScala.map(nodeToExpr),
+                  withDistinct))
             case (None, None, None, Some(clusterExprs)) =>
-              Sort(clusterExprs.getChildren.map(nodeToExpr).map(SortOrder(_, Ascending)), false,
-                RepartitionByExpression(clusterExprs.getChildren.map(nodeToExpr), withDistinct))
+              Sort(
+                clusterExprs.getChildren.asScala.map(nodeToExpr).map(SortOrder(_, Ascending)),
+                false,
+                RepartitionByExpression(
+                  clusterExprs.getChildren.asScala.map(nodeToExpr),
+                  withDistinct))
             case (None, None, None, None) => withDistinct
             case _ => sys.error("Unsupported set of ordering / distribution clauses.")
           }
 
         val withLimit =
-          limitClause.map(l => nodeToExpr(l.getChildren.head))
+          limitClause.map(l => nodeToExpr(l.getChildren.iterator().next()))
             .map(Limit(_, withSort))
             .getOrElse(withSort)
 
         // Collect all window specifications defined in the WINDOW clause.
-        val windowDefinitions = windowClause.map(_.getChildren.toSeq.collect {
+        val windowDefinitions = windowClause.map(_.getChildren.asScala.collect {
           case Token("TOK_WINDOWDEF",
           Token(windowName, Nil) :: Token("TOK_WINDOWSPEC", spec) :: Nil) =>
             windowName -> nodesToWindowSpecification(spec)
@@ -1063,7 +1077,8 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
       val Token("TOK_SELECT",
             Token("TOK_SELEXPR", clauses) :: Nil) = selectClause
 
-      val alias = getClause("TOK_TABALIAS", clauses).getChildren.head.asInstanceOf[ASTNode].getText
+      val alias = getClause("TOK_TABALIAS", clauses).getChildren.iterator().next()
+        .asInstanceOf[ASTNode].getText
 
       val (generator, attributes) = nodesToGenerator(clauses)
         Generate(
@@ -1092,7 +1107,9 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
       }
 
       val tableIdent =
-        tableNameParts.getChildren.map{ case Token(part, Nil) => cleanIdentifier(part)} match {
+        tableNameParts.getChildren.asScala.map {
+          case Token(part, Nil) => cleanIdentifier(part)
+        } match {
           case Seq(tableOnly) => Seq(tableOnly)
           case Seq(databaseName, table) => Seq(databaseName, table)
           case other => sys.error("Hive only supports tables names like 'tableName' " +
@@ -1139,7 +1156,8 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
 
       val isPreserved = tableOrdinals.map(i => (i - 1 < 0) || joinArgs(i - 1).getText == "PRESERVE")
       val tables = tableOrdinals.map(i => nodeToRelation(joinArgs(i)))
-      val joinExpressions = tableOrdinals.map(i => joinArgs(i + 1).getChildren.map(nodeToExpr))
+      val joinExpressions =
+        tableOrdinals.map(i => joinArgs(i + 1).getChildren.asScala.map(nodeToExpr))
 
       val joinConditions = joinExpressions.sliding(2).map {
         case Seq(c1, c2) =>
@@ -1164,7 +1182,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
             joinType = joinType.remove(joinType.length - 1))
       }
 
-      val groups = (0 until joinExpressions.head.size).map(i => Coalesce(joinExpressions.map(_(i))))
+      val groups = joinExpressions.head.indices.map(i => Coalesce(joinExpressions.map(_(i))))
 
       // Unique join is not really the same as an outer join so we must group together results where
       // the joinExpressions are the same, taking the First of each value is only okay because the
@@ -1229,7 +1247,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
 
       val tableIdent = extractTableIdent(tableNameParts)
 
-      val partitionKeys = partitionClause.map(_.getChildren.map {
+      val partitionKeys = partitionClause.map(_.getChildren.asScala.map {
         // Parse partitions. We also make keys case insensitive.
         case Token("TOK_PARTVAL", Token(key, Nil) :: Token(value, Nil) :: Nil) =>
           cleanIdentifier(key.toLowerCase) -> Some(PlanUtils.stripQuotes(value))
@@ -1249,7 +1267,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
 
       val tableIdent = extractTableIdent(tableNameParts)
 
-      val partitionKeys = partitionClause.map(_.getChildren.map {
+      val partitionKeys = partitionClause.map(_.getChildren.asScala.map {
         // Parse partitions. We also make keys case insensitive.
         case Token("TOK_PARTVAL", Token(key, Nil) :: Token(value, Nil) :: Nil) =>
           cleanIdentifier(key.toLowerCase) -> Some(PlanUtils.stripQuotes(value))
@@ -1590,18 +1608,18 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
         val (partitionByClause :: orderByClause :: sortByClause :: clusterByClause :: Nil) =
           getClauses(
             Seq("TOK_DISTRIBUTEBY", "TOK_ORDERBY", "TOK_SORTBY", "TOK_CLUSTERBY"),
-            partitionAndOrdering.getChildren.toSeq.asInstanceOf[Seq[ASTNode]])
+            partitionAndOrdering.getChildren.asScala.asInstanceOf[Seq[ASTNode]])
 
         (partitionByClause, orderByClause.orElse(sortByClause), clusterByClause) match {
           case (Some(partitionByExpr), Some(orderByExpr), None) =>
-            (partitionByExpr.getChildren.map(nodeToExpr),
-              orderByExpr.getChildren.map(nodeToSortOrder))
+            (partitionByExpr.getChildren.asScala.map(nodeToExpr),
+              orderByExpr.getChildren.asScala.map(nodeToSortOrder))
           case (Some(partitionByExpr), None, None) =>
-            (partitionByExpr.getChildren.map(nodeToExpr), Nil)
+            (partitionByExpr.getChildren.asScala.map(nodeToExpr), Nil)
           case (None, Some(orderByExpr), None) =>
-            (Nil, orderByExpr.getChildren.map(nodeToSortOrder))
+            (Nil, orderByExpr.getChildren.asScala.map(nodeToSortOrder))
           case (None, None, Some(clusterByExpr)) =>
-            val expressions = clusterByExpr.getChildren.map(nodeToExpr)
+            val expressions = clusterByExpr.getChildren.asScala.map(nodeToExpr)
             (expressions, expressions.map(SortOrder(_, Ascending)))
           case _ =>
             throw new NotImplementedError(
@@ -1639,7 +1657,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
           }
 
           rowFrame.orElse(rangeFrame).map { frame =>
-            frame.getChildren.toList match {
+            frame.getChildren.asScala.toList match {
               case precedingNode :: followingNode :: Nil =>
                 SpecifiedWindowFrame(
                   frameType,
@@ -1701,7 +1719,7 @@ https://cwiki.apache.org/confluence/display/Hive/Enhanced+Aggregation%2C+Cube%2C
       case other => sys.error(s"Non ASTNode encountered: $other")
     }
 
-    Option(node.getChildren).map(_.toList).getOrElse(Nil).foreach(dumpTree(_, builder, indent + 1))
+    Option(node.getChildren).map(_.asScala).getOrElse(Nil).foreach(dumpTree(_, builder, indent + 1))
     builder
   }
 }
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveShim.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveShim.scala
index 267074f3ad..004805f3ae 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveShim.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/HiveShim.scala
@@ -22,8 +22,7 @@ import java.rmi.server.UID
 
 import org.apache.avro.Schema
 
-/* Implicit conversions */
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.language.implicitConversions
 import scala.reflect.ClassTag
 
@@ -73,7 +72,7 @@ private[hive] object HiveShim {
    */
   def appendReadColumns(conf: Configuration, ids: Seq[Integer], names: Seq[String]) {
     if (ids != null && ids.nonEmpty) {
-      ColumnProjectionUtils.appendReadColumns(conf, ids)
+      ColumnProjectionUtils.appendReadColumns(conf, ids.asJava)
     }
     if (names != null && names.nonEmpty) {
       appendReadColumnNames(conf, names)
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/ClientWrapper.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/ClientWrapper.scala
index f49c97de8f..4d1e3ed919 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/ClientWrapper.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/ClientWrapper.scala
@@ -21,7 +21,7 @@ import java.io.{File, PrintStream}
 import java.util.{Map => JMap}
 import javax.annotation.concurrent.GuardedBy
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.language.reflectiveCalls
 
 import org.apache.hadoop.fs.Path
@@ -305,10 +305,11 @@ private[hive] class ClientWrapper(
       HiveTable(
         name = h.getTableName,
         specifiedDatabase = Option(h.getDbName),
-        schema = h.getCols.map(f => HiveColumn(f.getName, f.getType, f.getComment)),
-        partitionColumns = h.getPartCols.map(f => HiveColumn(f.getName, f.getType, f.getComment)),
-        properties = h.getParameters.toMap,
-        serdeProperties = h.getTTable.getSd.getSerdeInfo.getParameters.toMap,
+        schema = h.getCols.asScala.map(f => HiveColumn(f.getName, f.getType, f.getComment)),
+        partitionColumns = h.getPartCols.asScala.map(f =>
+          HiveColumn(f.getName, f.getType, f.getComment)),
+        properties = h.getParameters.asScala.toMap,
+        serdeProperties = h.getTTable.getSd.getSerdeInfo.getParameters.asScala.toMap,
         tableType = h.getTableType match {
           case HTableType.MANAGED_TABLE => ManagedTable
           case HTableType.EXTERNAL_TABLE => ExternalTable
@@ -334,9 +335,9 @@ private[hive] class ClientWrapper(
   private def toQlTable(table: HiveTable): metadata.Table = {
     val qlTable = new metadata.Table(table.database, table.name)
 
-    qlTable.setFields(table.schema.map(c => new FieldSchema(c.name, c.hiveType, c.comment)))
+    qlTable.setFields(table.schema.map(c => new FieldSchema(c.name, c.hiveType, c.comment)).asJava)
     qlTable.setPartCols(
-      table.partitionColumns.map(c => new FieldSchema(c.name, c.hiveType, c.comment)))
+      table.partitionColumns.map(c => new FieldSchema(c.name, c.hiveType, c.comment)).asJava)
     table.properties.foreach { case (k, v) => qlTable.setProperty(k, v) }
     table.serdeProperties.foreach { case (k, v) => qlTable.setSerdeParam(k, v) }
 
@@ -366,13 +367,13 @@ private[hive] class ClientWrapper(
   private def toHivePartition(partition: metadata.Partition): HivePartition = {
     val apiPartition = partition.getTPartition
     HivePartition(
-      values = Option(apiPartition.getValues).map(_.toSeq).getOrElse(Seq.empty),
+      values = Option(apiPartition.getValues).map(_.asScala).getOrElse(Seq.empty),
       storage = HiveStorageDescriptor(
         location = apiPartition.getSd.getLocation,
         inputFormat = apiPartition.getSd.getInputFormat,
         outputFormat = apiPartition.getSd.getOutputFormat,
         serde = apiPartition.getSd.getSerdeInfo.getSerializationLib,
-        serdeProperties = apiPartition.getSd.getSerdeInfo.getParameters.toMap))
+        serdeProperties = apiPartition.getSd.getSerdeInfo.getParameters.asScala.toMap))
   }
 
   override def getPartitionOption(
@@ -397,7 +398,7 @@ private[hive] class ClientWrapper(
   }
 
   override def listTables(dbName: String): Seq[String] = withHiveState {
-    client.getAllTables(dbName)
+    client.getAllTables(dbName).asScala
   }
 
   /**
@@ -514,17 +515,17 @@ private[hive] class ClientWrapper(
   }
 
   def reset(): Unit = withHiveState {
-    client.getAllTables("default").foreach { t =>
+    client.getAllTables("default").asScala.foreach { t =>
         logDebug(s"Deleting table $t")
         val table = client.getTable("default", t)
-        client.getIndexes("default", t, 255).foreach { index =>
+        client.getIndexes("default", t, 255).asScala.foreach { index =>
           shim.dropIndex(client, "default", t, index.getIndexName)
         }
         if (!table.isIndexTable) {
           client.dropTable("default", t)
         }
       }
-      client.getAllDatabases.filterNot(_ == "default").foreach { db =>
+      client.getAllDatabases.asScala.filterNot(_ == "default").foreach { db =>
         logDebug(s"Dropping Database: $db")
         client.dropDatabase(db, true, false, true)
       }
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveShim.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveShim.scala
index 8fc8935b1d..48bbb21e6c 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveShim.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveShim.scala
@@ -23,7 +23,7 @@ import java.net.URI
 import java.util.{ArrayList => JArrayList, List => JList, Map => JMap, Set => JSet}
 import java.util.concurrent.TimeUnit
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.hadoop.fs.{FileSystem, Path}
 import org.apache.hadoop.hive.conf.HiveConf
@@ -201,7 +201,7 @@ private[client] class Shim_v0_12 extends Shim with Logging {
     setDataLocationMethod.invoke(table, new URI(loc))
 
   override def getAllPartitions(hive: Hive, table: Table): Seq[Partition] =
-    getAllPartitionsMethod.invoke(hive, table).asInstanceOf[JSet[Partition]].toSeq
+    getAllPartitionsMethod.invoke(hive, table).asInstanceOf[JSet[Partition]].asScala.toSeq
 
   override def getPartitionsByFilter(
       hive: Hive,
@@ -220,7 +220,7 @@ private[client] class Shim_v0_12 extends Shim with Logging {
   override def getDriverResults(driver: Driver): Seq[String] = {
     val res = new JArrayList[String]()
     getDriverResultsMethod.invoke(driver, res)
-    res.toSeq
+    res.asScala
   }
 
   override def getMetastoreClientConnectRetryDelayMillis(conf: HiveConf): Long = {
@@ -310,7 +310,7 @@ private[client] class Shim_v0_13 extends Shim_v0_12 {
     setDataLocationMethod.invoke(table, new Path(loc))
 
   override def getAllPartitions(hive: Hive, table: Table): Seq[Partition] =
-    getAllPartitionsMethod.invoke(hive, table).asInstanceOf[JSet[Partition]].toSeq
+    getAllPartitionsMethod.invoke(hive, table).asInstanceOf[JSet[Partition]].asScala.toSeq
 
   /**
    * Converts catalyst expression to the format that Hive's getPartitionsByFilter() expects, i.e.
@@ -320,7 +320,7 @@ private[client] class Shim_v0_13 extends Shim_v0_12 {
    */
   def convertFilters(table: Table, filters: Seq[Expression]): String = {
     // hive varchar is treated as catalyst string, but hive varchar can't be pushed down.
-    val varcharKeys = table.getPartitionKeys
+    val varcharKeys = table.getPartitionKeys.asScala
       .filter(col => col.getType.startsWith(serdeConstants.VARCHAR_TYPE_NAME))
       .map(col => col.getName).toSet
 
@@ -354,7 +354,7 @@ private[client] class Shim_v0_13 extends Shim_v0_12 {
         getPartitionsByFilterMethod.invoke(hive, table, filter).asInstanceOf[JArrayList[Partition]]
       }
 
-    partitions.toSeq
+    partitions.asScala.toSeq
   }
 
   override def getCommandProcessor(token: String, conf: HiveConf): CommandProcessor =
@@ -363,7 +363,7 @@ private[client] class Shim_v0_13 extends Shim_v0_12 {
   override def getDriverResults(driver: Driver): Seq[String] = {
     val res = new JArrayList[Object]()
     getDriverResultsMethod.invoke(driver, res)
-    res.map { r =>
+    res.asScala.map { r =>
       r match {
         case s: String => s
         case a: Array[Object] => a(0).asInstanceOf[String]
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/DescribeHiveTableCommand.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/DescribeHiveTableCommand.scala
index 5f0ed5393d..441b6b6033 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/DescribeHiveTableCommand.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/DescribeHiveTableCommand.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.hive.execution
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.hadoop.hive.metastore.api.FieldSchema
 
@@ -39,8 +39,8 @@ case class DescribeHiveTableCommand(
     // Trying to mimic the format of Hive's output. But not exactly the same.
     var results: Seq[(String, String, String)] = Nil
 
-    val columns: Seq[FieldSchema] = table.hiveQlTable.getCols
-    val partitionColumns: Seq[FieldSchema] = table.hiveQlTable.getPartCols
+    val columns: Seq[FieldSchema] = table.hiveQlTable.getCols.asScala
+    val partitionColumns: Seq[FieldSchema] = table.hiveQlTable.getPartCols.asScala
     results ++= columns.map(field => (field.getName, field.getType, field.getComment))
     if (partitionColumns.nonEmpty) {
       val partColumnInfo =
@@ -48,7 +48,7 @@ case class DescribeHiveTableCommand(
       results ++=
         partColumnInfo ++
           Seq(("# Partition Information", "", "")) ++
-          Seq((s"# ${output.get(0).name}", output.get(1).name, output.get(2).name)) ++
+          Seq((s"# ${output(0).name}", output(1).name, output(2).name)) ++
           partColumnInfo
     }
 
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/HiveTableScan.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/HiveTableScan.scala
index ba7eb15a1c..806d2b9b0b 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/HiveTableScan.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/HiveTableScan.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.hive.execution
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.hadoop.hive.conf.HiveConf
 import org.apache.hadoop.hive.ql.metadata.{Partition => HivePartition}
@@ -98,7 +98,7 @@ case class HiveTableScan(
       .asInstanceOf[StructObjectInspector]
 
     val columnTypeNames = structOI
-      .getAllStructFieldRefs
+      .getAllStructFieldRefs.asScala
       .map(_.getFieldObjectInspector)
       .map(TypeInfoUtils.getTypeInfoFromObjectInspector(_).getTypeName)
       .mkString(",")
@@ -118,9 +118,8 @@ case class HiveTableScan(
       case None => partitions
       case Some(shouldKeep) => partitions.filter { part =>
         val dataTypes = relation.partitionKeys.map(_.dataType)
-        val castedValues = for ((value, dataType) <- part.getValues.zip(dataTypes)) yield {
-          castFromString(value, dataType)
-        }
+        val castedValues = part.getValues.asScala.zip(dataTypes)
+          .map { case (value, dataType) => castFromString(value, dataType) }
 
         // Only partitioned values are needed here, since the predicate has already been bound to
         // partition key attribute references.
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/InsertIntoHiveTable.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/InsertIntoHiveTable.scala
index 62efda613a..58f7fa640e 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/InsertIntoHiveTable.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/InsertIntoHiveTable.scala
@@ -19,9 +19,10 @@ package org.apache.spark.sql.hive.execution
 
 import java.util
 
+import scala.collection.JavaConverters._
+
 import org.apache.hadoop.hive.conf.HiveConf
 import org.apache.hadoop.hive.conf.HiveConf.ConfVars
-import org.apache.hadoop.hive.metastore.MetaStoreUtils
 import org.apache.hadoop.hive.ql.plan.TableDesc
 import org.apache.hadoop.hive.ql.{Context, ErrorMsg}
 import org.apache.hadoop.hive.serde2.Serializer
@@ -38,8 +39,6 @@ import org.apache.spark.sql.hive.HiveShim.{ShimFileSinkDesc => FileSinkDesc}
 import org.apache.spark.sql.hive._
 import org.apache.spark.sql.types.DataType
 import org.apache.spark.{SparkException, TaskContext}
-
-import scala.collection.JavaConversions._
 import org.apache.spark.util.SerializableJobConf
 
 private[hive]
@@ -94,7 +93,8 @@ case class InsertIntoHiveTable(
           ObjectInspectorCopyOption.JAVA)
         .asInstanceOf[StructObjectInspector]
 
-      val fieldOIs = standardOI.getAllStructFieldRefs.map(_.getFieldObjectInspector).toArray
+      val fieldOIs = standardOI.getAllStructFieldRefs.asScala
+        .map(_.getFieldObjectInspector).toArray
       val dataTypes: Array[DataType] = child.output.map(_.dataType).toArray
       val wrappers = fieldOIs.zip(dataTypes).map { case (f, dt) => wrapperFor(f, dt)}
       val outputData = new Array[Any](fieldOIs.length)
@@ -198,7 +198,7 @@ case class InsertIntoHiveTable(
 
       // loadPartition call orders directories created on the iteration order of the this map
       val orderedPartitionSpec = new util.LinkedHashMap[String, String]()
-      table.hiveQlTable.getPartCols().foreach { entry =>
+      table.hiveQlTable.getPartCols.asScala.foreach { entry =>
         orderedPartitionSpec.put(entry.getName, partitionSpec.get(entry.getName).getOrElse(""))
       }
 
@@ -226,7 +226,7 @@ case class InsertIntoHiveTable(
         val oldPart =
           catalog.client.getPartitionOption(
             catalog.client.getTable(table.databaseName, table.tableName),
-            partitionSpec)
+            partitionSpec.asJava)
 
         if (oldPart.isEmpty || !ifNotExists) {
             catalog.client.loadPartition(
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/ScriptTransformation.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/ScriptTransformation.scala
index ade27454b9..c7651daffe 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/ScriptTransformation.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/execution/ScriptTransformation.scala
@@ -21,7 +21,7 @@ import java.io._
 import java.util.Properties
 import javax.annotation.Nullable
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.control.NonFatal
 
 import org.apache.hadoop.hive.serde.serdeConstants
@@ -61,7 +61,7 @@ case class ScriptTransformation(
   protected override def doExecute(): RDD[InternalRow] = {
     def processIterator(inputIterator: Iterator[InternalRow]): Iterator[InternalRow] = {
       val cmd = List("/bin/bash", "-c", script)
-      val builder = new ProcessBuilder(cmd)
+      val builder = new ProcessBuilder(cmd.asJava)
 
       val proc = builder.start()
       val inputStream = proc.getInputStream
@@ -172,10 +172,10 @@ case class ScriptTransformation(
             val fieldList = outputSoi.getAllStructFieldRefs()
             var i = 0
             while (i < dataList.size()) {
-              if (dataList(i) == null) {
+              if (dataList.get(i) == null) {
                 mutableRow.setNullAt(i)
               } else {
-                mutableRow(i) = unwrap(dataList(i), fieldList(i).getFieldObjectInspector)
+                mutableRow(i) = unwrap(dataList.get(i), fieldList.get(i).getFieldObjectInspector)
               }
               i += 1
             }
@@ -307,7 +307,7 @@ case class HiveScriptIOSchema (
       val serde = initSerDe(serdeClass, columns, columnTypes, inputSerdeProps)
       val fieldObjectInspectors = columnTypes.map(toInspector)
       val objectInspector = ObjectInspectorFactory
-        .getStandardStructObjectInspector(columns, fieldObjectInspectors)
+        .getStandardStructObjectInspector(columns.asJava, fieldObjectInspectors.asJava)
         .asInstanceOf[ObjectInspector]
       (serde, objectInspector)
     }
@@ -342,7 +342,7 @@ case class HiveScriptIOSchema (
     propsMap = propsMap + (serdeConstants.LIST_COLUMN_TYPES -> columnTypesNames)
 
     val properties = new Properties()
-    properties.putAll(propsMap)
+    properties.putAll(propsMap.asJava)
     serde.initialize(null, properties)
 
     serde
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala
index 7182246e46..cad02373e5 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/hiveUDFs.scala
@@ -18,7 +18,7 @@
 package org.apache.spark.sql.hive
 
 import scala.collection.mutable.ArrayBuffer
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.Try
 
 import org.apache.hadoop.hive.serde2.objectinspector.{ObjectInspector, ConstantObjectInspector}
@@ -81,8 +81,7 @@ private[hive] class HiveFunctionRegistry(underlying: analysis.FunctionRegistry)
 
   /* List all of the registered function names. */
   override def listFunction(): Seq[String] = {
-    val a = FunctionRegistry.getFunctionNames ++ underlying.listFunction()
-    a.toList.sorted
+    (FunctionRegistry.getFunctionNames.asScala ++ underlying.listFunction()).toList.sorted
   }
 
   /* Get the class of the registered function by specified name. */
@@ -116,7 +115,7 @@ private[hive] case class HiveSimpleUDF(funcWrapper: HiveFunctionWrapper, childre
 
   @transient
   private lazy val method =
-    function.getResolver.getEvalMethod(children.map(_.dataType.toTypeInfo))
+    function.getResolver.getEvalMethod(children.map(_.dataType.toTypeInfo).asJava)
 
   @transient
   private lazy val arguments = children.map(toInspector).toArray
@@ -541,7 +540,7 @@ private[hive] case class HiveGenericUDTF(
   @transient
   protected lazy val collector = new UDTFCollector
 
-  lazy val elementTypes = outputInspector.getAllStructFieldRefs.map {
+  lazy val elementTypes = outputInspector.getAllStructFieldRefs.asScala.map {
     field => (inspectorToDataType(field.getFieldObjectInspector), true)
   }
 
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/orc/OrcRelation.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/orc/OrcRelation.scala
index 9f4f8b5789..1cff5cf9c3 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/orc/OrcRelation.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/orc/OrcRelation.scala
@@ -19,6 +19,8 @@ package org.apache.spark.sql.hive.orc
 
 import java.util.Properties
 
+import scala.collection.JavaConverters._
+
 import com.google.common.base.Objects
 import org.apache.hadoop.conf.Configuration
 import org.apache.hadoop.fs.{FileStatus, Path}
@@ -43,9 +45,6 @@ import org.apache.spark.sql.types.StructType
 import org.apache.spark.sql.{Row, SQLContext}
 import org.apache.spark.util.SerializableConfiguration
 
-/* Implicit conversions */
-import scala.collection.JavaConversions._
-
 private[sql] class DefaultSource extends HadoopFsRelationProvider with DataSourceRegister {
 
   override def shortName(): String = "orc"
@@ -97,7 +96,8 @@ private[orc] class OrcOutputWriter(
   private val reusableOutputBuffer = new Array[Any](dataSchema.length)
 
   // Used to convert Catalyst values into Hadoop `Writable`s.
-  private val wrappers = structOI.getAllStructFieldRefs.zip(dataSchema.fields.map(_.dataType))
+  private val wrappers = structOI.getAllStructFieldRefs.asScala
+    .zip(dataSchema.fields.map(_.dataType))
     .map { case (ref, dt) =>
       wrapperFor(ref.getFieldObjectInspector, dt)
     }.toArray
diff --git a/sql/hive/src/main/scala/org/apache/spark/sql/hive/test/TestHive.scala b/sql/hive/src/main/scala/org/apache/spark/sql/hive/test/TestHive.scala
index 4da86636ac..572eaebe81 100644
--- a/sql/hive/src/main/scala/org/apache/spark/sql/hive/test/TestHive.scala
+++ b/sql/hive/src/main/scala/org/apache/spark/sql/hive/test/TestHive.scala
@@ -20,6 +20,7 @@ package org.apache.spark.sql.hive.test
 import java.io.File
 import java.util.{Set => JavaSet}
 
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.language.implicitConversions
 
@@ -37,9 +38,6 @@ import org.apache.spark.sql.hive.execution.HiveNativeCommand
 import org.apache.spark.util.{ShutdownHookManager, Utils}
 import org.apache.spark.{SparkConf, SparkContext}
 
-/* Implicit conversions */
-import scala.collection.JavaConversions._
-
 // SPARK-3729: Test key required to check for initialization errors with config.
 object TestHive
   extends TestHiveContext(
@@ -405,7 +403,7 @@ class TestHiveContext(sc: SparkContext) extends HiveContext(sc) {
   def reset() {
     try {
       // HACK: Hive is too noisy by default.
-      org.apache.log4j.LogManager.getCurrentLoggers.foreach { log =>
+      org.apache.log4j.LogManager.getCurrentLoggers.asScala.foreach { log =>
         log.asInstanceOf[org.apache.log4j.Logger].setLevel(org.apache.log4j.Level.WARN)
       }
 
@@ -415,9 +413,8 @@ class TestHiveContext(sc: SparkContext) extends HiveContext(sc) {
       catalog.client.reset()
       catalog.unregisterAllTables()
 
-      FunctionRegistry.getFunctionNames.filterNot(originalUDFs.contains(_)).foreach { udfName =>
-        FunctionRegistry.unregisterTemporaryUDF(udfName)
-      }
+      FunctionRegistry.getFunctionNames.asScala.filterNot(originalUDFs.contains(_)).
+        foreach { udfName => FunctionRegistry.unregisterTemporaryUDF(udfName) }
 
       // Some tests corrupt this value on purpose, which breaks the RESET call below.
       hiveconf.set("fs.default.name", new File(".").toURI.toString)
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/client/FiltersSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/client/FiltersSuite.scala
index 0efcf80bd4..5e7b93d457 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/client/FiltersSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/client/FiltersSuite.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.hive.client
 
-import scala.collection.JavaConversions._
+import java.util.Collections
 
 import org.apache.hadoop.hive.metastore.api.FieldSchema
 import org.apache.hadoop.hive.serde.serdeConstants
@@ -38,7 +38,7 @@ class FiltersSuite extends SparkFunSuite with Logging {
   private val varCharCol = new FieldSchema()
   varCharCol.setName("varchar")
   varCharCol.setType(serdeConstants.VARCHAR_TYPE_NAME)
-  testTable.setPartCols(varCharCol :: Nil)
+  testTable.setPartCols(Collections.singletonList(varCharCol))
 
   filterTest("string filter",
     (a("stringcol", StringType) > Literal("test")) :: Nil,
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveUDFSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveUDFSuite.scala
index b03a351323..9c10ffe111 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveUDFSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/HiveUDFSuite.scala
@@ -18,8 +18,7 @@
 package org.apache.spark.sql.hive.execution
 
 import java.io.{DataInput, DataOutput}
-import java.util
-import java.util.Properties
+import java.util.{ArrayList, Arrays, Properties}
 
 import org.apache.hadoop.conf.Configuration
 import org.apache.hadoop.hive.ql.udf.generic.{GenericUDAFAverage, GenericUDF}
@@ -33,8 +32,6 @@ import org.apache.spark.sql.hive.test.TestHive
 
 import org.apache.spark.util.Utils
 
-import scala.collection.JavaConversions._
-
 case class Fields(f1: Int, f2: Int, f3: Int, f4: Int, f5: Int)
 
 // Case classes for the custom UDF's.
@@ -326,11 +323,11 @@ class PairSerDe extends AbstractSerDe {
   override def getObjectInspector: ObjectInspector = {
     ObjectInspectorFactory
       .getStandardStructObjectInspector(
-        Seq("pair"),
-        Seq(ObjectInspectorFactory.getStandardStructObjectInspector(
-          Seq("id", "value"),
-          Seq(PrimitiveObjectInspectorFactory.javaIntObjectInspector,
-              PrimitiveObjectInspectorFactory.javaIntObjectInspector))
+        Arrays.asList("pair"),
+        Arrays.asList(ObjectInspectorFactory.getStandardStructObjectInspector(
+          Arrays.asList("id", "value"),
+          Arrays.asList(PrimitiveObjectInspectorFactory.javaIntObjectInspector,
+                        PrimitiveObjectInspectorFactory.javaIntObjectInspector))
     ))
   }
 
@@ -343,10 +340,10 @@ class PairSerDe extends AbstractSerDe {
   override def deserialize(value: Writable): AnyRef = {
     val pair = value.asInstanceOf[TestPair]
 
-    val row = new util.ArrayList[util.ArrayList[AnyRef]]
-    row.add(new util.ArrayList[AnyRef](2))
-    row(0).add(Integer.valueOf(pair.entry._1))
-    row(0).add(Integer.valueOf(pair.entry._2))
+    val row = new ArrayList[ArrayList[AnyRef]]
+    row.add(new ArrayList[AnyRef](2))
+    row.get(0).add(Integer.valueOf(pair.entry._1))
+    row.get(0).add(Integer.valueOf(pair.entry._2))
 
     row
   }
@@ -355,9 +352,9 @@ class PairSerDe extends AbstractSerDe {
 class PairUDF extends GenericUDF {
   override def initialize(p1: Array[ObjectInspector]): ObjectInspector =
     ObjectInspectorFactory.getStandardStructObjectInspector(
-      Seq("id", "value"),
-      Seq(PrimitiveObjectInspectorFactory.javaIntObjectInspector,
-        PrimitiveObjectInspectorFactory.javaIntObjectInspector)
+      Arrays.asList("id", "value"),
+      Arrays.asList(PrimitiveObjectInspectorFactory.javaIntObjectInspector,
+                    PrimitiveObjectInspectorFactory.javaIntObjectInspector)
   )
 
   override def evaluate(args: Array[DeferredObject]): AnyRef = {
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/PruningSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/PruningSuite.scala
index 3bf8f3ac20..210d566745 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/PruningSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/PruningSuite.scala
@@ -17,13 +17,12 @@
 
 package org.apache.spark.sql.hive.execution
 
+import scala.collection.JavaConverters._
+
 import org.scalatest.BeforeAndAfter
 
 import org.apache.spark.sql.hive.test.TestHive
 
-/* Implicit conversions */
-import scala.collection.JavaConversions._
-
 /**
  * A set of test cases that validate partition and column pruning.
  */
@@ -161,7 +160,7 @@ class PruningSuite extends HiveComparisonTest with BeforeAndAfter {
       assert(actualOutputColumns === expectedOutputColumns, "Output columns mismatch")
       assert(actualScannedColumns === expectedScannedColumns, "Scanned columns mismatch")
 
-      val actualPartitions = actualPartValues.map(_.toSeq.mkString(",")).sorted
+      val actualPartitions = actualPartValues.map(_.asScala.mkString(",")).sorted
       val expectedPartitions = expectedPartValues.map(_.mkString(",")).sorted
 
       assert(actualPartitions === expectedPartitions, "Partitions selected do not match")
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
index 55ecbd5b5f..1ff1d9a293 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/hive/execution/SQLQuerySuite.scala
@@ -19,7 +19,7 @@ package org.apache.spark.sql.hive.execution
 
 import java.sql.{Date, Timestamp}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.sql._
 import org.apache.spark.sql.catalyst.DefaultParserDialect
@@ -164,7 +164,7 @@ class SQLQuerySuite extends QueryTest with SQLTestUtils {
   test("show functions") {
     val allFunctions =
       (FunctionRegistry.builtin.listFunction().toSet[String] ++
-        org.apache.hadoop.hive.ql.exec.FunctionRegistry.getFunctionNames).toList.sorted
+        org.apache.hadoop.hive.ql.exec.FunctionRegistry.getFunctionNames.asScala).toList.sorted
     checkAnswer(sql("SHOW functions"), allFunctions.map(Row(_)))
     checkAnswer(sql("SHOW functions abs"), Row("abs"))
     checkAnswer(sql("SHOW functions 'abs'"), Row("abs"))
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/sources/hadoopFsRelationSuites.scala b/sql/hive/src/test/scala/org/apache/spark/sql/sources/hadoopFsRelationSuites.scala
index 5bbca14bad..7966b43596 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/sources/hadoopFsRelationSuites.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/sources/hadoopFsRelationSuites.scala
@@ -17,9 +17,7 @@
 
 package org.apache.spark.sql.sources
 
-import java.sql.Date
-
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.hadoop.conf.Configuration
 import org.apache.hadoop.fs.Path
@@ -552,7 +550,7 @@ abstract class HadoopFsRelationTest extends QueryTest with SQLTestUtils {
     } finally {
       // Hadoop 1 doesn't have `Configuration.unset`
       configuration.clear()
-      clonedConf.foreach(entry => configuration.set(entry.getKey, entry.getValue))
+      clonedConf.asScala.foreach(entry => configuration.set(entry.getKey, entry.getValue))
     }
   }
 
@@ -600,7 +598,7 @@ abstract class HadoopFsRelationTest extends QueryTest with SQLTestUtils {
     } finally {
       // Hadoop 1 doesn't have `Configuration.unset`
       configuration.clear()
-      clonedConf.foreach(entry => configuration.set(entry.getKey, entry.getValue))
+      clonedConf.asScala.foreach(entry => configuration.set(entry.getKey, entry.getValue))
       sqlContext.sparkContext.conf.set("spark.speculation", speculationEnabled.toString)
     }
   }
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStreamLike.scala b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStreamLike.scala
index 214cd80108..edfa474677 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStreamLike.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaDStreamLike.scala
@@ -17,11 +17,10 @@
 
 package org.apache.spark.streaming.api.java
 
-import java.util
 import java.lang.{Long => JLong}
 import java.util.{List => JList}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.language.implicitConversions
 import scala.reflect.ClassTag
 
@@ -145,8 +144,7 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This, R], R <: JavaRDDLike[T
    * an array.
    */
   def glom(): JavaDStream[JList[T]] =
-    new JavaDStream(dstream.glom().map(x => new java.util.ArrayList[T](x.toSeq)))
-
+    new JavaDStream(dstream.glom().map(_.toSeq.asJava))
 
 
   /** Return the [[org.apache.spark.streaming.StreamingContext]] associated with this DStream */
@@ -191,7 +189,7 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This, R], R <: JavaRDDLike[T
    */
   def mapPartitions[U](f: FlatMapFunction[java.util.Iterator[T], U]): JavaDStream[U] = {
     def fn: (Iterator[T]) => Iterator[U] = {
-      (x: Iterator[T]) => asScalaIterator(f.call(asJavaIterator(x)).iterator())
+      (x: Iterator[T]) => f.call(x.asJava).iterator().asScala
     }
     new JavaDStream(dstream.mapPartitions(fn)(fakeClassTag[U]))(fakeClassTag[U])
   }
@@ -204,7 +202,7 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This, R], R <: JavaRDDLike[T
   def mapPartitionsToPair[K2, V2](f: PairFlatMapFunction[java.util.Iterator[T], K2, V2])
   : JavaPairDStream[K2, V2] = {
     def fn: (Iterator[T]) => Iterator[(K2, V2)] = {
-      (x: Iterator[T]) => asScalaIterator(f.call(asJavaIterator(x)).iterator())
+      (x: Iterator[T]) => f.call(x.asJava).iterator().asScala
     }
     new JavaPairDStream(dstream.mapPartitions(fn))(fakeClassTag[K2], fakeClassTag[V2])
   }
@@ -282,7 +280,7 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This, R], R <: JavaRDDLike[T
    * Return all the RDDs between 'fromDuration' to 'toDuration' (both included)
    */
   def slice(fromTime: Time, toTime: Time): JList[R] = {
-    new util.ArrayList(dstream.slice(fromTime, toTime).map(wrapRDD(_)).toSeq)
+    dstream.slice(fromTime, toTime).map(wrapRDD).asJava
   }
 
   /**
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaPairDStream.scala b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaPairDStream.scala
index 26383e4201..e2aec6c2f6 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaPairDStream.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaPairDStream.scala
@@ -20,7 +20,7 @@ package org.apache.spark.streaming.api.java
 import java.lang.{Long => JLong, Iterable => JIterable}
 import java.util.{List => JList}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.language.implicitConversions
 import scala.reflect.ClassTag
 
@@ -116,14 +116,14 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
    * generate the RDDs with Spark's default number of partitions.
    */
   def groupByKey(): JavaPairDStream[K, JIterable[V]] =
-    dstream.groupByKey().mapValues(asJavaIterable _)
+    dstream.groupByKey().mapValues(_.asJava)
 
   /**
    * Return a new DStream by applying `groupByKey` to each RDD. Hash partitioning is used to
    * generate the RDDs with `numPartitions` partitions.
    */
   def groupByKey(numPartitions: Int): JavaPairDStream[K, JIterable[V]] =
-    dstream.groupByKey(numPartitions).mapValues(asJavaIterable _)
+    dstream.groupByKey(numPartitions).mapValues(_.asJava)
 
   /**
    * Return a new DStream by applying `groupByKey` on each RDD of `this` DStream.
@@ -132,7 +132,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
    * is used to control the partitioning of each RDD.
    */
   def groupByKey(partitioner: Partitioner): JavaPairDStream[K, JIterable[V]] =
-    dstream.groupByKey(partitioner).mapValues(asJavaIterable _)
+    dstream.groupByKey(partitioner).mapValues(_.asJava)
 
   /**
    * Return a new DStream by applying `reduceByKey` to each RDD. The values for each key are
@@ -197,7 +197,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
    *                       batching interval
    */
   def groupByKeyAndWindow(windowDuration: Duration): JavaPairDStream[K, JIterable[V]] = {
-    dstream.groupByKeyAndWindow(windowDuration).mapValues(asJavaIterable _)
+    dstream.groupByKeyAndWindow(windowDuration).mapValues(_.asJava)
   }
 
   /**
@@ -212,7 +212,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
    */
   def groupByKeyAndWindow(windowDuration: Duration, slideDuration: Duration)
   : JavaPairDStream[K, JIterable[V]] = {
-    dstream.groupByKeyAndWindow(windowDuration, slideDuration).mapValues(asJavaIterable _)
+    dstream.groupByKeyAndWindow(windowDuration, slideDuration).mapValues(_.asJava)
   }
 
   /**
@@ -228,8 +228,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
    */
   def groupByKeyAndWindow(windowDuration: Duration, slideDuration: Duration, numPartitions: Int)
     : JavaPairDStream[K, JIterable[V]] = {
-    dstream.groupByKeyAndWindow(windowDuration, slideDuration, numPartitions)
-      .mapValues(asJavaIterable _)
+    dstream.groupByKeyAndWindow(windowDuration, slideDuration, numPartitions).mapValues(_.asJava)
   }
 
   /**
@@ -248,8 +247,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
       slideDuration: Duration,
       partitioner: Partitioner
     ): JavaPairDStream[K, JIterable[V]] = {
-    dstream.groupByKeyAndWindow(windowDuration, slideDuration, partitioner)
-      .mapValues(asJavaIterable _)
+    dstream.groupByKeyAndWindow(windowDuration, slideDuration, partitioner).mapValues(_.asJava)
   }
 
   /**
@@ -431,7 +429,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
   private def convertUpdateStateFunction[S](in: JFunction2[JList[V], Optional[S], Optional[S]]):
   (Seq[V], Option[S]) => Option[S] = {
     val scalaFunc: (Seq[V], Option[S]) => Option[S] = (values, state) => {
-      val list: JList[V] = values
+      val list: JList[V] = values.asJava
       val scalaState: Optional[S] = JavaUtils.optionToOptional(state)
       val result: Optional[S] = in.apply(list, scalaState)
       result.isPresent match {
@@ -539,7 +537,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
    */
   def cogroup[W](other: JavaPairDStream[K, W]): JavaPairDStream[K, (JIterable[V], JIterable[W])] = {
     implicit val cm: ClassTag[W] = fakeClassTag
-    dstream.cogroup(other.dstream).mapValues(t => (asJavaIterable(t._1), asJavaIterable((t._2))))
+    dstream.cogroup(other.dstream).mapValues(t => (t._1.asJava, t._2.asJava))
   }
 
   /**
@@ -551,8 +549,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
       numPartitions: Int
     ): JavaPairDStream[K, (JIterable[V], JIterable[W])] = {
     implicit val cm: ClassTag[W] = fakeClassTag
-    dstream.cogroup(other.dstream, numPartitions)
-           .mapValues(t => (asJavaIterable(t._1), asJavaIterable((t._2))))
+    dstream.cogroup(other.dstream, numPartitions).mapValues(t => (t._1.asJava, t._2.asJava))
   }
 
   /**
@@ -564,8 +561,7 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
       partitioner: Partitioner
     ): JavaPairDStream[K, (JIterable[V], JIterable[W])] = {
     implicit val cm: ClassTag[W] = fakeClassTag
-    dstream.cogroup(other.dstream, partitioner)
-           .mapValues(t => (asJavaIterable(t._1), asJavaIterable((t._2))))
+    dstream.cogroup(other.dstream, partitioner).mapValues(t => (t._1.asJava, t._2.asJava))
   }
 
   /**
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaStreamingContext.scala b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaStreamingContext.scala
index 35cc3ce5cf..13f371f296 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaStreamingContext.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaStreamingContext.scala
@@ -21,7 +21,7 @@ import java.lang.{Boolean => JBoolean}
 import java.io.{Closeable, InputStream}
 import java.util.{List => JList, Map => JMap}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
 import akka.actor.{Props, SupervisorStrategy}
@@ -115,7 +115,13 @@ class JavaStreamingContext(val ssc: StreamingContext) extends Closeable {
     sparkHome: String,
     jars: Array[String],
     environment: JMap[String, String]) =
-    this(new StreamingContext(master, appName, batchDuration, sparkHome, jars, environment))
+    this(new StreamingContext(
+      master,
+      appName,
+      batchDuration,
+      sparkHome,
+      jars,
+      environment.asScala))
 
   /**
    * Create a JavaStreamingContext using an existing JavaSparkContext.
@@ -197,7 +203,7 @@ class JavaStreamingContext(val ssc: StreamingContext) extends Closeable {
       converter: JFunction[InputStream, java.lang.Iterable[T]],
       storageLevel: StorageLevel)
   : JavaReceiverInputDStream[T] = {
-    def fn: (InputStream) => Iterator[T] = (x: InputStream) => converter.call(x).toIterator
+    def fn: (InputStream) => Iterator[T] = (x: InputStream) => converter.call(x).iterator().asScala
     implicit val cmt: ClassTag[T] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[T]]
     ssc.socketStream(hostname, port, fn, storageLevel)
@@ -432,7 +438,7 @@ class JavaStreamingContext(val ssc: StreamingContext) extends Closeable {
     implicit val cm: ClassTag[T] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[T]]
     val sQueue = new scala.collection.mutable.Queue[RDD[T]]
-    sQueue.enqueue(queue.map(_.rdd).toSeq: _*)
+    sQueue.enqueue(queue.asScala.map(_.rdd).toSeq: _*)
     ssc.queueStream(sQueue)
   }
 
@@ -456,7 +462,7 @@ class JavaStreamingContext(val ssc: StreamingContext) extends Closeable {
     implicit val cm: ClassTag[T] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[T]]
     val sQueue = new scala.collection.mutable.Queue[RDD[T]]
-    sQueue.enqueue(queue.map(_.rdd).toSeq: _*)
+    sQueue.enqueue(queue.asScala.map(_.rdd).toSeq: _*)
     ssc.queueStream(sQueue, oneAtATime)
   }
 
@@ -481,7 +487,7 @@ class JavaStreamingContext(val ssc: StreamingContext) extends Closeable {
     implicit val cm: ClassTag[T] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[T]]
     val sQueue = new scala.collection.mutable.Queue[RDD[T]]
-    sQueue.enqueue(queue.map(_.rdd).toSeq: _*)
+    sQueue.enqueue(queue.asScala.map(_.rdd).toSeq: _*)
     ssc.queueStream(sQueue, oneAtATime, defaultRDD.rdd)
   }
 
@@ -500,7 +506,7 @@ class JavaStreamingContext(val ssc: StreamingContext) extends Closeable {
    * Create a unified DStream from multiple DStreams of the same type and same slide duration.
    */
   def union[T](first: JavaDStream[T], rest: JList[JavaDStream[T]]): JavaDStream[T] = {
-    val dstreams: Seq[DStream[T]] = (Seq(first) ++ asScalaBuffer(rest)).map(_.dstream)
+    val dstreams: Seq[DStream[T]] = (Seq(first) ++ rest.asScala).map(_.dstream)
     implicit val cm: ClassTag[T] = first.classTag
     ssc.union(dstreams)(cm)
   }
@@ -512,7 +518,7 @@ class JavaStreamingContext(val ssc: StreamingContext) extends Closeable {
       first: JavaPairDStream[K, V],
       rest: JList[JavaPairDStream[K, V]]
     ): JavaPairDStream[K, V] = {
-    val dstreams: Seq[DStream[(K, V)]] = (Seq(first) ++ asScalaBuffer(rest)).map(_.dstream)
+    val dstreams: Seq[DStream[(K, V)]] = (Seq(first) ++ rest.asScala).map(_.dstream)
     implicit val cm: ClassTag[(K, V)] = first.classTag
     implicit val kcm: ClassTag[K] = first.kManifest
     implicit val vcm: ClassTag[V] = first.vManifest
@@ -534,12 +540,11 @@ class JavaStreamingContext(val ssc: StreamingContext) extends Closeable {
     ): JavaDStream[T] = {
     implicit val cmt: ClassTag[T] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[T]]
-    val scalaDStreams = dstreams.map(_.dstream).toSeq
     val scalaTransformFunc = (rdds: Seq[RDD[_]], time: Time) => {
-      val jrdds = rdds.map(rdd => JavaRDD.fromRDD[AnyRef](rdd.asInstanceOf[RDD[AnyRef]])).toList
+      val jrdds = rdds.map(JavaRDD.fromRDD(_)).asJava
       transformFunc.call(jrdds, time).rdd
     }
-    ssc.transform(scalaDStreams, scalaTransformFunc)
+    ssc.transform(dstreams.asScala.map(_.dstream).toSeq, scalaTransformFunc)
   }
 
   /**
@@ -559,12 +564,11 @@ class JavaStreamingContext(val ssc: StreamingContext) extends Closeable {
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[K]]
     implicit val cmv: ClassTag[V] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[V]]
-    val scalaDStreams = dstreams.map(_.dstream).toSeq
     val scalaTransformFunc = (rdds: Seq[RDD[_]], time: Time) => {
-      val jrdds = rdds.map(rdd => JavaRDD.fromRDD[AnyRef](rdd.asInstanceOf[RDD[AnyRef]])).toList
+      val jrdds = rdds.map(JavaRDD.fromRDD(_)).asJava
       transformFunc.call(jrdds, time).rdd
     }
-    ssc.transform(scalaDStreams, scalaTransformFunc)
+    ssc.transform(dstreams.asScala.map(_.dstream).toSeq, scalaTransformFunc)
   }
 
   /**
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/api/python/PythonDStream.scala b/streaming/src/main/scala/org/apache/spark/streaming/api/python/PythonDStream.scala
index d06401245f..2c373640d2 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/api/python/PythonDStream.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/api/python/PythonDStream.scala
@@ -20,14 +20,13 @@ package org.apache.spark.streaming.api.python
 import java.io.{ObjectInputStream, ObjectOutputStream}
 import java.lang.reflect.Proxy
 import java.util.{ArrayList => JArrayList, List => JList}
-import scala.collection.JavaConversions._
+
 import scala.collection.JavaConverters._
 import scala.language.existentials
 
 import py4j.GatewayServer
 
 import org.apache.spark.api.java._
-import org.apache.spark.api.python._
 import org.apache.spark.rdd.RDD
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.streaming.{Interval, Duration, Time}
@@ -161,7 +160,7 @@ private[python] object PythonDStream {
    */
   def toRDDQueue(rdds: JArrayList[JavaRDD[Array[Byte]]]): java.util.Queue[JavaRDD[Array[Byte]]] = {
     val queue = new java.util.LinkedList[JavaRDD[Array[Byte]]]
-    rdds.forall(queue.add(_))
+    rdds.asScala.foreach(queue.add)
     queue
   }
 }
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/receiver/Receiver.scala b/streaming/src/main/scala/org/apache/spark/streaming/receiver/Receiver.scala
index 554aae0117..2252e28f22 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/receiver/Receiver.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/receiver/Receiver.scala
@@ -20,7 +20,7 @@ package org.apache.spark.streaming.receiver
 import java.nio.ByteBuffer
 
 import scala.collection.mutable.ArrayBuffer
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import org.apache.spark.storage.StorageLevel
 import org.apache.spark.annotation.DeveloperApi
@@ -144,12 +144,12 @@ abstract class Receiver[T](val storageLevel: StorageLevel) extends Serializable
    * for being used in the corresponding InputDStream.
    */
   def store(dataIterator: java.util.Iterator[T], metadata: Any) {
-    supervisor.pushIterator(dataIterator, Some(metadata), None)
+    supervisor.pushIterator(dataIterator.asScala, Some(metadata), None)
   }
 
   /** Store an iterator of received data as a data block into Spark's memory. */
   def store(dataIterator: java.util.Iterator[T]) {
-    supervisor.pushIterator(dataIterator, None, None)
+    supervisor.pushIterator(dataIterator.asScala, None, None)
   }
 
   /**
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/scheduler/JobScheduler.scala b/streaming/src/main/scala/org/apache/spark/streaming/scheduler/JobScheduler.scala
index 6d4cdc4aa6..0cd39594ee 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/scheduler/JobScheduler.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/scheduler/JobScheduler.scala
@@ -19,7 +19,7 @@ package org.apache.spark.streaming.scheduler
 
 import java.util.concurrent.{ConcurrentHashMap, TimeUnit}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.util.{Failure, Success}
 
 import org.apache.spark.Logging
@@ -128,7 +128,7 @@ class JobScheduler(val ssc: StreamingContext) extends Logging {
   }
 
   def getPendingTimes(): Seq[Time] = {
-    jobSets.keySet.toSeq
+    jobSets.asScala.keys.toSeq
   }
 
   def reportError(msg: String, e: Throwable) {
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/scheduler/ReceivedBlockTracker.scala b/streaming/src/main/scala/org/apache/spark/streaming/scheduler/ReceivedBlockTracker.scala
index 53b96d51c9..f2711d1355 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/scheduler/ReceivedBlockTracker.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/scheduler/ReceivedBlockTracker.scala
@@ -19,6 +19,7 @@ package org.apache.spark.streaming.scheduler
 
 import java.nio.ByteBuffer
 
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.language.implicitConversions
 
@@ -196,8 +197,7 @@ private[streaming] class ReceivedBlockTracker(
 
     writeAheadLogOption.foreach { writeAheadLog =>
       logInfo(s"Recovering from write ahead logs in ${checkpointDirOption.get}")
-      import scala.collection.JavaConversions._
-      writeAheadLog.readAll().foreach { byteBuffer =>
+      writeAheadLog.readAll().asScala.foreach { byteBuffer =>
         logTrace("Recovering record " + byteBuffer)
         Utils.deserialize[ReceivedBlockTrackerLogEvent](
           byteBuffer.array, Thread.currentThread().getContextClassLoader) match {
diff --git a/streaming/src/main/scala/org/apache/spark/streaming/util/FileBasedWriteAheadLog.scala b/streaming/src/main/scala/org/apache/spark/streaming/util/FileBasedWriteAheadLog.scala
index fe6328b1ce..9f4a4d6806 100644
--- a/streaming/src/main/scala/org/apache/spark/streaming/util/FileBasedWriteAheadLog.scala
+++ b/streaming/src/main/scala/org/apache/spark/streaming/util/FileBasedWriteAheadLog.scala
@@ -19,6 +19,7 @@ package org.apache.spark.streaming.util
 import java.nio.ByteBuffer
 import java.util.{Iterator => JIterator}
 
+import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 import scala.concurrent.{Await, ExecutionContext, Future}
 import scala.language.postfixOps
@@ -118,7 +119,6 @@ private[streaming] class FileBasedWriteAheadLog(
    * hence the implementation is kept simple.
    */
   def readAll(): JIterator[ByteBuffer] = synchronized {
-    import scala.collection.JavaConversions._
     val logFilesToRead = pastLogs.map{ _.path} ++ currentLogPath
     logInfo("Reading from the logs: " + logFilesToRead.mkString("\n"))
 
@@ -126,7 +126,7 @@ private[streaming] class FileBasedWriteAheadLog(
       logDebug(s"Creating log reader with $file")
       val reader = new FileBasedWriteAheadLogReader(file, hadoopConf)
       CompletionIterator[ByteBuffer, Iterator[ByteBuffer]](reader, reader.close _)
-    } flatMap { x => x }
+    }.flatten.asJava
   }
 
   /**
diff --git a/streaming/src/test/java/org/apache/spark/streaming/JavaTestUtils.scala b/streaming/src/test/java/org/apache/spark/streaming/JavaTestUtils.scala
index bb80bff6dc..57b50bdfd6 100644
--- a/streaming/src/test/java/org/apache/spark/streaming/JavaTestUtils.scala
+++ b/streaming/src/test/java/org/apache/spark/streaming/JavaTestUtils.scala
@@ -17,16 +17,13 @@
 
 package org.apache.spark.streaming
 
-import scala.collection.mutable.{SynchronizedBuffer, ArrayBuffer}
+import java.util.{List => JList}
+
+import scala.collection.JavaConverters._
 import scala.reflect.ClassTag
 
-import java.util.{List => JList}
-import org.apache.spark.streaming.api.java.{JavaPairDStream, JavaDStreamLike, JavaDStream, JavaStreamingContext}
-import org.apache.spark.streaming._
-import java.util.ArrayList
-import collection.JavaConversions._
 import org.apache.spark.api.java.JavaRDDLike
-import org.apache.spark.streaming.dstream.DStream
+import org.apache.spark.streaming.api.java.{JavaDStreamLike, JavaDStream, JavaStreamingContext}
 
 /** Exposes streaming test functionality in a Java-friendly way. */
 trait JavaTestBase extends TestSuiteBase {
@@ -39,7 +36,7 @@ trait JavaTestBase extends TestSuiteBase {
       ssc: JavaStreamingContext,
       data: JList[JList[T]],
       numPartitions: Int) = {
-    val seqData = data.map(Seq(_:_*))
+    val seqData = data.asScala.map(_.asScala)
 
     implicit val cm: ClassTag[T] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[T]]
@@ -72,9 +69,7 @@ trait JavaTestBase extends TestSuiteBase {
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[V]]
     ssc.getState()
     val res = runStreams[V](ssc.ssc, numBatches, numExpectedOutput)
-    val out = new ArrayList[JList[V]]()
-    res.map(entry => out.append(new ArrayList[V](entry)))
-    out
+    res.map(_.asJava).asJava
   }
 
   /**
@@ -90,12 +85,7 @@ trait JavaTestBase extends TestSuiteBase {
     implicit val cm: ClassTag[V] =
       implicitly[ClassTag[AnyRef]].asInstanceOf[ClassTag[V]]
     val res = runStreamsWithPartitions[V](ssc.ssc, numBatches, numExpectedOutput)
-    val out = new ArrayList[JList[JList[V]]]()
-    res.map{entry =>
-      val lists = entry.map(new ArrayList[V](_))
-      out.append(new ArrayList[JList[V]](lists))
-    }
-    out
+    res.map(entry => entry.map(_.asJava).asJava).asJava
   }
 }
 
diff --git a/streaming/src/test/scala/org/apache/spark/streaming/util/WriteAheadLogSuite.scala b/streaming/src/test/scala/org/apache/spark/streaming/util/WriteAheadLogSuite.scala
index 325ff7c74c..5e49fd0076 100644
--- a/streaming/src/test/scala/org/apache/spark/streaming/util/WriteAheadLogSuite.scala
+++ b/streaming/src/test/scala/org/apache/spark/streaming/util/WriteAheadLogSuite.scala
@@ -20,6 +20,7 @@ import java.io._
 import java.nio.ByteBuffer
 import java.util
 
+import scala.collection.JavaConverters._
 import scala.collection.mutable.ArrayBuffer
 import scala.concurrent.duration._
 import scala.language.{implicitConversions, postfixOps}
@@ -417,9 +418,8 @@ object WriteAheadLogSuite {
 
   /** Read all the data in the log file in a directory using the WriteAheadLog class. */
   def readDataUsingWriteAheadLog(logDirectory: String): Seq[String] = {
-    import scala.collection.JavaConversions._
     val wal = new FileBasedWriteAheadLog(new SparkConf(), logDirectory, hadoopConf, 1, 1)
-    val data = wal.readAll().map(byteBufferToString).toSeq
+    val data = wal.readAll().asScala.map(byteBufferToString).toSeq
     wal.close()
     data
   }
diff --git a/tools/src/main/scala/org/apache/spark/tools/GenerateMIMAIgnore.scala b/tools/src/main/scala/org/apache/spark/tools/GenerateMIMAIgnore.scala
index 9418beb6b3..a0524cabff 100644
--- a/tools/src/main/scala/org/apache/spark/tools/GenerateMIMAIgnore.scala
+++ b/tools/src/main/scala/org/apache/spark/tools/GenerateMIMAIgnore.scala
@@ -22,7 +22,7 @@ import java.io.File
 import java.util.jar.JarFile
 
 import scala.collection.mutable
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.reflect.runtime.universe.runtimeMirror
 import scala.reflect.runtime.{universe => unv}
 import scala.util.Try
@@ -161,7 +161,7 @@ object GenerateMIMAIgnore {
     val path = packageName.replace('.', '/')
     val resources = classLoader.getResources(path)
 
-    val jars = resources.filter(x => x.getProtocol == "jar")
+    val jars = resources.asScala.filter(_.getProtocol == "jar")
       .map(_.getFile.split(":")(1).split("!")(0)).toSeq
 
     jars.flatMap(getClassesFromJar(_, path))
@@ -175,7 +175,7 @@ object GenerateMIMAIgnore {
   private def getClassesFromJar(jarPath: String, packageName: String) = {
     import scala.collection.mutable
     val jar = new JarFile(new File(jarPath))
-    val enums = jar.entries().map(_.getName).filter(_.startsWith(packageName))
+    val enums = jar.entries().asScala.map(_.getName).filter(_.startsWith(packageName))
     val classes = mutable.HashSet[Class[_]]()
     for (entry <- enums if entry.endsWith(".class")) {
       try {
diff --git a/yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala b/yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala
index bff585b46c..e9a02baafd 100644
--- a/yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala
+++ b/yarn/src/main/scala/org/apache/spark/deploy/yarn/Client.scala
@@ -25,7 +25,7 @@ import java.security.PrivilegedExceptionAction
 import java.util.{Properties, UUID}
 import java.util.zip.{ZipEntry, ZipOutputStream}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet, ListBuffer, Map}
 import scala.reflect.runtime.universe
 import scala.util.{Try, Success, Failure}
@@ -511,7 +511,7 @@ private[spark] class Client(
     val nns = YarnSparkHadoopUtil.get.getNameNodesToAccess(sparkConf) + stagingDirPath
     YarnSparkHadoopUtil.get.obtainTokensForNamenodes(
       nns, hadoopConf, creds, Some(sparkConf.get("spark.yarn.principal")))
-    val t = creds.getAllTokens
+    val t = creds.getAllTokens.asScala
       .filter(_.getKind == DelegationTokenIdentifier.HDFS_DELEGATION_KIND)
       .head
     val newExpiration = t.renew(hadoopConf)
@@ -650,8 +650,8 @@ private[spark] class Client(
     distCacheMgr.setDistArchivesEnv(launchEnv)
 
     val amContainer = Records.newRecord(classOf[ContainerLaunchContext])
-    amContainer.setLocalResources(localResources)
-    amContainer.setEnvironment(launchEnv)
+    amContainer.setLocalResources(localResources.asJava)
+    amContainer.setEnvironment(launchEnv.asJava)
 
     val javaOpts = ListBuffer[String]()
 
@@ -782,7 +782,7 @@ private[spark] class Client(
 
     // TODO: it would be nicer to just make sure there are no null commands here
     val printableCommands = commands.map(s => if (s == null) "null" else s).toList
-    amContainer.setCommands(printableCommands)
+    amContainer.setCommands(printableCommands.asJava)
 
     logDebug("===============================================================================")
     logDebug("YARN AM launch context:")
@@ -797,7 +797,8 @@ private[spark] class Client(
 
     // send the acl settings into YARN to control who has access via YARN interfaces
     val securityManager = new SecurityManager(sparkConf)
-    amContainer.setApplicationACLs(YarnSparkHadoopUtil.getApplicationAclsForYarn(securityManager))
+    amContainer.setApplicationACLs(
+      YarnSparkHadoopUtil.getApplicationAclsForYarn(securityManager).asJava)
     setupSecurityToken(amContainer)
     UserGroupInformation.getCurrentUser().addCredentials(credentials)
 
diff --git a/yarn/src/main/scala/org/apache/spark/deploy/yarn/ExecutorRunnable.scala b/yarn/src/main/scala/org/apache/spark/deploy/yarn/ExecutorRunnable.scala
index 4cc50483a1..9abd09b3cc 100644
--- a/yarn/src/main/scala/org/apache/spark/deploy/yarn/ExecutorRunnable.scala
+++ b/yarn/src/main/scala/org/apache/spark/deploy/yarn/ExecutorRunnable.scala
@@ -20,14 +20,13 @@ package org.apache.spark.deploy.yarn
 import java.io.File
 import java.net.URI
 import java.nio.ByteBuffer
+import java.util.Collections
 
-import org.apache.hadoop.fs.Path
-import org.apache.hadoop.yarn.api.ApplicationConstants.Environment
-import org.apache.spark.util.Utils
-
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{HashMap, ListBuffer}
 
+import org.apache.hadoop.fs.Path
+import org.apache.hadoop.yarn.api.ApplicationConstants.Environment
 import org.apache.hadoop.conf.Configuration
 import org.apache.hadoop.io.DataOutputBuffer
 import org.apache.hadoop.security.UserGroupInformation
@@ -40,6 +39,7 @@ import org.apache.hadoop.yarn.util.{ConverterUtils, Records}
 
 import org.apache.spark.{Logging, SecurityManager, SparkConf, SparkException}
 import org.apache.spark.network.util.JavaUtils
+import org.apache.spark.util.Utils
 
 class ExecutorRunnable(
     container: Container,
@@ -74,9 +74,9 @@ class ExecutorRunnable(
       .asInstanceOf[ContainerLaunchContext]
 
     val localResources = prepareLocalResources
-    ctx.setLocalResources(localResources)
+    ctx.setLocalResources(localResources.asJava)
 
-    ctx.setEnvironment(env)
+    ctx.setEnvironment(env.asJava)
 
     val credentials = UserGroupInformation.getCurrentUser().getCredentials()
     val dob = new DataOutputBuffer()
@@ -96,8 +96,9 @@ class ExecutorRunnable(
       |===============================================================================
       """.stripMargin)
 
-    ctx.setCommands(commands)
-    ctx.setApplicationACLs(YarnSparkHadoopUtil.getApplicationAclsForYarn(securityMgr))
+    ctx.setCommands(commands.asJava)
+    ctx.setApplicationACLs(
+      YarnSparkHadoopUtil.getApplicationAclsForYarn(securityMgr).asJava)
 
     // If external shuffle service is enabled, register with the Yarn shuffle service already
     // started on the NodeManager and, if authentication is enabled, provide it with our secret
@@ -112,7 +113,7 @@ class ExecutorRunnable(
           // Authentication is not enabled, so just provide dummy metadata
           ByteBuffer.allocate(0)
         }
-      ctx.setServiceData(Map[String, ByteBuffer]("spark_shuffle" -> secretBytes))
+      ctx.setServiceData(Collections.singletonMap("spark_shuffle", secretBytes))
     }
 
     // Send the start request to the ContainerManager
@@ -314,7 +315,8 @@ class ExecutorRunnable(
       env("SPARK_LOG_URL_STDOUT") = s"$baseUrl/stdout?start=-4096"
     }
 
-    System.getenv().filterKeys(_.startsWith("SPARK")).foreach { case (k, v) => env(k) = v }
+    System.getenv().asScala.filterKeys(_.startsWith("SPARK"))
+      .foreach { case (k, v) => env(k) = v }
     env
   }
 }
diff --git a/yarn/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocator.scala b/yarn/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocator.scala
index ccf753e69f..5f897cbcb4 100644
--- a/yarn/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocator.scala
+++ b/yarn/src/main/scala/org/apache/spark/deploy/yarn/YarnAllocator.scala
@@ -21,9 +21,7 @@ import java.util.Collections
 import java.util.concurrent._
 import java.util.regex.Pattern
 
-import org.apache.spark.util.Utils
-
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet}
 
 import com.google.common.util.concurrent.ThreadFactoryBuilder
@@ -39,8 +37,8 @@ import org.apache.log4j.{Level, Logger}
 import org.apache.spark.{Logging, SecurityManager, SparkConf}
 import org.apache.spark.deploy.yarn.YarnSparkHadoopUtil._
 import org.apache.spark.rpc.RpcEndpointRef
-import org.apache.spark.scheduler.cluster.CoarseGrainedSchedulerBackend
 import org.apache.spark.scheduler.cluster.CoarseGrainedClusterMessages._
+import org.apache.spark.util.Utils
 
 /**
  * YarnAllocator is charged with requesting containers from the YARN ResourceManager and deciding
@@ -164,7 +162,7 @@ private[yarn] class YarnAllocator(
    * Number of container requests at the given location that have not yet been fulfilled.
    */
   private def getNumPendingAtLocation(location: String): Int =
-    amClient.getMatchingRequests(RM_REQUEST_PRIORITY, location, resource).map(_.size).sum
+    amClient.getMatchingRequests(RM_REQUEST_PRIORITY, location, resource).asScala.map(_.size).sum
 
   /**
    * Request as many executors from the ResourceManager as needed to reach the desired total. If
@@ -231,14 +229,14 @@ private[yarn] class YarnAllocator(
           numExecutorsRunning,
           allocateResponse.getAvailableResources))
 
-      handleAllocatedContainers(allocatedContainers)
+      handleAllocatedContainers(allocatedContainers.asScala)
     }
 
     val completedContainers = allocateResponse.getCompletedContainersStatuses()
     if (completedContainers.size > 0) {
       logDebug("Completed %d containers".format(completedContainers.size))
 
-      processCompletedContainers(completedContainers)
+      processCompletedContainers(completedContainers.asScala)
 
       logDebug("Finished processing %d completed containers. Current running executor count: %d."
         .format(completedContainers.size, numExecutorsRunning))
@@ -271,7 +269,7 @@ private[yarn] class YarnAllocator(
         val request = createContainerRequest(resource, locality.nodes, locality.racks)
         amClient.addContainerRequest(request)
         val nodes = request.getNodes
-        val hostStr = if (nodes == null || nodes.isEmpty) "Any" else nodes.last
+        val hostStr = if (nodes == null || nodes.isEmpty) "Any" else nodes.asScala.last
         logInfo(s"Container request (host: $hostStr, capability: $resource)")
       }
     } else if (missing < 0) {
@@ -280,7 +278,8 @@ private[yarn] class YarnAllocator(
 
       val matchingRequests = amClient.getMatchingRequests(RM_REQUEST_PRIORITY, ANY_HOST, resource)
       if (!matchingRequests.isEmpty) {
-        matchingRequests.head.take(numToCancel).foreach(amClient.removeContainerRequest)
+        matchingRequests.iterator().next().asScala
+          .take(numToCancel).foreach(amClient.removeContainerRequest)
       } else {
         logWarning("Expected to find pending requests, but found none.")
       }
@@ -459,7 +458,7 @@ private[yarn] class YarnAllocator(
         }
       }
 
-      if (allocatedContainerToHostMap.containsKey(containerId)) {
+      if (allocatedContainerToHostMap.contains(containerId)) {
         val host = allocatedContainerToHostMap.get(containerId).get
         val containerSet = allocatedHostToContainersMap.get(host).get
 
diff --git a/yarn/src/main/scala/org/apache/spark/deploy/yarn/YarnRMClient.scala b/yarn/src/main/scala/org/apache/spark/deploy/yarn/YarnRMClient.scala
index 4999f9c062..df042bf291 100644
--- a/yarn/src/main/scala/org/apache/spark/deploy/yarn/YarnRMClient.scala
+++ b/yarn/src/main/scala/org/apache/spark/deploy/yarn/YarnRMClient.scala
@@ -19,17 +19,15 @@ package org.apache.spark.deploy.yarn
 
 import java.util.{List => JList}
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.{Map, Set}
 import scala.util.Try
 
 import org.apache.hadoop.conf.Configuration
-import org.apache.hadoop.yarn.api.ApplicationConstants
 import org.apache.hadoop.yarn.api.records._
 import org.apache.hadoop.yarn.client.api.AMRMClient
 import org.apache.hadoop.yarn.client.api.AMRMClient.ContainerRequest
 import org.apache.hadoop.yarn.conf.YarnConfiguration
-import org.apache.hadoop.yarn.util.ConverterUtils
 import org.apache.hadoop.yarn.webapp.util.WebAppUtils
 
 import org.apache.spark.{Logging, SecurityManager, SparkConf}
@@ -108,8 +106,8 @@ private[spark] class YarnRMClient(args: ApplicationMasterArguments) extends Logg
       val method = classOf[WebAppUtils].getMethod("getProxyHostsAndPortsForAmFilter",
         classOf[Configuration])
       val proxies = method.invoke(null, conf).asInstanceOf[JList[String]]
-      val hosts = proxies.map { proxy => proxy.split(":")(0) }
-      val uriBases = proxies.map { proxy => prefix + proxy + proxyBase }
+      val hosts = proxies.asScala.map { proxy => proxy.split(":")(0) }
+      val uriBases = proxies.asScala.map { proxy => prefix + proxy + proxyBase }
       Map("PROXY_HOSTS" -> hosts.mkString(","), "PROXY_URI_BASES" -> uriBases.mkString(","))
     } catch {
       case e: NoSuchMethodException =>
diff --git a/yarn/src/test/scala/org/apache/spark/deploy/yarn/BaseYarnClusterSuite.scala b/yarn/src/test/scala/org/apache/spark/deploy/yarn/BaseYarnClusterSuite.scala
index 128e996b71..b4f8049bff 100644
--- a/yarn/src/test/scala/org/apache/spark/deploy/yarn/BaseYarnClusterSuite.scala
+++ b/yarn/src/test/scala/org/apache/spark/deploy/yarn/BaseYarnClusterSuite.scala
@@ -21,7 +21,7 @@ import java.io.{File, FileOutputStream, OutputStreamWriter}
 import java.util.Properties
 import java.util.concurrent.TimeUnit
 
-import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 
 import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.Files
@@ -132,7 +132,7 @@ abstract class BaseYarnClusterSuite
     props.setProperty("spark.driver.extraJavaOptions", "-Dfoo=\"one two three\"")
     props.setProperty("spark.executor.extraJavaOptions", "-Dfoo=\"one two three\"")
 
-    yarnCluster.getConfig().foreach { e =>
+    yarnCluster.getConfig.asScala.foreach { e =>
       props.setProperty("spark.hadoop." + e.getKey(), e.getValue())
     }
 
@@ -149,7 +149,7 @@ abstract class BaseYarnClusterSuite
     props.store(writer, "Spark properties.")
     writer.close()
 
-    val extraJarArgs = if (!extraJars.isEmpty()) Seq("--jars", extraJars.mkString(",")) else Nil
+    val extraJarArgs = if (extraJars.nonEmpty) Seq("--jars", extraJars.mkString(",")) else Nil
     val mainArgs =
       if (klass.endsWith(".py")) {
         Seq(klass)
diff --git a/yarn/src/test/scala/org/apache/spark/deploy/yarn/ClientSuite.scala b/yarn/src/test/scala/org/apache/spark/deploy/yarn/ClientSuite.scala
index 0a5402c89e..e7f2501e78 100644
--- a/yarn/src/test/scala/org/apache/spark/deploy/yarn/ClientSuite.scala
+++ b/yarn/src/test/scala/org/apache/spark/deploy/yarn/ClientSuite.scala
@@ -20,8 +20,8 @@ package org.apache.spark.deploy.yarn
 import java.io.File
 import java.net.URI
 
-import scala.collection.JavaConversions._
-import scala.collection.mutable.{ HashMap => MutableHashMap }
+import scala.collection.JavaConverters._
+import scala.collection.mutable.{HashMap => MutableHashMap}
 import scala.reflect.ClassTag
 import scala.util.Try
 
@@ -38,7 +38,7 @@ import org.mockito.Matchers._
 import org.mockito.Mockito._
 import org.scalatest.{BeforeAndAfterAll, Matchers}
 
-import org.apache.spark.{SparkConf, SparkException, SparkFunSuite}
+import org.apache.spark.{SparkConf, SparkFunSuite}
 import org.apache.spark.util.Utils
 
 class ClientSuite extends SparkFunSuite with Matchers with BeforeAndAfterAll {
@@ -201,7 +201,7 @@ class ClientSuite extends SparkFunSuite with Matchers with BeforeAndAfterAll {
     appContext.getClass.getMethods.filter(_.getName.equals("getApplicationTags")).foreach{ method =>
       val tags = method.invoke(appContext).asInstanceOf[java.util.Set[String]]
       tags should contain allOf ("tag1", "dup", "tag2", "multi word")
-      tags.filter(!_.isEmpty).size should be (4)
+      tags.asScala.filter(_.nonEmpty).size should be (4)
     }
     appContext.getMaxAppAttempts should be (42)
   }
diff --git a/yarn/src/test/scala/org/apache/spark/deploy/yarn/YarnClusterSuite.scala b/yarn/src/test/scala/org/apache/spark/deploy/yarn/YarnClusterSuite.scala
index 128350b648..5a4ea2ea2f 100644
--- a/yarn/src/test/scala/org/apache/spark/deploy/yarn/YarnClusterSuite.scala
+++ b/yarn/src/test/scala/org/apache/spark/deploy/yarn/YarnClusterSuite.scala
@@ -21,7 +21,6 @@ import java.io.File
 import java.net.URL
 
 import scala.collection.mutable
-import scala.collection.JavaConversions._
 
 import com.google.common.base.Charsets.UTF_8
 import com.google.common.io.{ByteStreams, Files}
@@ -216,8 +215,8 @@ private object YarnClusterDriver extends Logging with Matchers {
       assert(listener.driverLogs.nonEmpty)
       val driverLogs = listener.driverLogs.get
       assert(driverLogs.size === 2)
-      assert(driverLogs.containsKey("stderr"))
-      assert(driverLogs.containsKey("stdout"))
+      assert(driverLogs.contains("stderr"))
+      assert(driverLogs.contains("stdout"))
       val urlStr = driverLogs("stderr")
       // Ensure that this is a valid URL, else this will throw an exception
       new URL(urlStr)
author	Sean Owen <sowen@cloudera.com>	2015-08-25 12:33:13 +0100
committer	Sean Owen <sowen@cloudera.com>	2015-08-25 12:33:13 +0100
commit	69c9c177160e32a2fbc9b36ecc52156077fca6fc (patch)
tree	57345aaf19c3149038bfca5c4ddccf33d41bdd5b
parent	7f1e507bf7e82bff323c5dec3c1ee044687c4173 (diff)
download	spark-69c9c177160e32a2fbc9b36ecc52156077fca6fc.tar.gz spark-69c9c177160e32a2fbc9b36ecc52156077fca6fc.tar.bz2 spark-69c9c177160e32a2fbc9b36ecc52156077fca6fc.zip