[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.

6 files changed, 27 insertions, 35 deletions

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))
   }