[SPARK-9534] [BUILD] Enable javac lint for scalac parity; fix a lot of build warnings, 1.5.0 edition

Enable most javac lint warnings; fix a lot of build warnings. In a few cases, touch up surrounding code in the process.

I'll explain several of the changes inline in comments.

Author: Sean Owen <sowen@cloudera.com>

Closes #7862 from srowen/SPARK-9534 and squashes the following commits:

ea51618 [Sean Owen] Enable most javac lint warnings; fix a lot of build warnings. In a few cases, touch up surrounding code in the process.

1 files changed, 32 insertions, 30 deletions

diff --git a/streaming/src/test/java/org/apache/spark/streaming/JavaWriteAheadLogSuite.java b/streaming/src/test/java/org/apache/spark/streaming/JavaWriteAheadLogSuite.java
index 50e8f9fc15..175b8a496b 100644
--- a/streaming/src/test/java/org/apache/spark/streaming/JavaWriteAheadLogSuite.java
+++ b/streaming/src/test/java/org/apache/spark/streaming/JavaWriteAheadLogSuite.java
@@ -17,13 +17,15 @@
 
 package org.apache.spark.streaming;
 
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.nio.ByteBuffer;
 import java.util.Arrays;
-import java.util.Collection;
+import java.util.Iterator;
+import java.util.List;
 
-import org.apache.commons.collections.CollectionUtils;
-import org.apache.commons.collections.Transformer;
+import com.google.common.base.Function;
+import com.google.common.collect.Iterators;
 import org.apache.spark.SparkConf;
 import org.apache.spark.streaming.util.WriteAheadLog;
 import org.apache.spark.streaming.util.WriteAheadLogRecordHandle;
@@ -32,40 +34,40 @@ import org.apache.spark.streaming.util.WriteAheadLogUtils;
 import org.junit.Test;
 import org.junit.Assert;
 
-class JavaWriteAheadLogSuiteHandle extends WriteAheadLogRecordHandle {
-  int index = -1;
-  public JavaWriteAheadLogSuiteHandle(int idx) {
-    index = idx;
-  }
-}
-
 public class JavaWriteAheadLogSuite extends WriteAheadLog {
 
-  class Record {
+  static class JavaWriteAheadLogSuiteHandle extends WriteAheadLogRecordHandle {
+    int index = -1;
+    JavaWriteAheadLogSuiteHandle(int idx) {
+      index = idx;
+    }
+  }
+
+  static class Record {
     long time;
     int index;
     ByteBuffer buffer;
 
-    public Record(long tym, int idx, ByteBuffer buf) {
+    Record(long tym, int idx, ByteBuffer buf) {
       index = idx;
       time = tym;
       buffer = buf;
     }
   }
   private int index = -1;
-  private ArrayList<Record> records = new ArrayList<Record>();
+  private final List<Record> records = new ArrayList<>();
 
 
   // Methods for WriteAheadLog
   @Override
-  public WriteAheadLogRecordHandle write(java.nio.ByteBuffer record, long time) {
+  public WriteAheadLogRecordHandle write(ByteBuffer record, long time) {
     index += 1;
-    records.add(new org.apache.spark.streaming.JavaWriteAheadLogSuite.Record(time, index, record));
+    records.add(new Record(time, index, record));
     return new JavaWriteAheadLogSuiteHandle(index);
   }
 
   @Override
-  public java.nio.ByteBuffer read(WriteAheadLogRecordHandle handle) {
+  public ByteBuffer read(WriteAheadLogRecordHandle handle) {
     if (handle instanceof JavaWriteAheadLogSuiteHandle) {
       int reqdIndex = ((JavaWriteAheadLogSuiteHandle) handle).index;
       for (Record record: records) {
@@ -78,14 +80,13 @@ public class JavaWriteAheadLogSuite extends WriteAheadLog {
   }
 
   @Override
-  public java.util.Iterator<java.nio.ByteBuffer> readAll() {
-    Collection<ByteBuffer> buffers = CollectionUtils.collect(records, new Transformer() {
+  public Iterator<ByteBuffer> readAll() {
+    return Iterators.transform(records.iterator(), new Function<Record,ByteBuffer>() {
       @Override
-      public Object transform(Object input) {
-        return ((Record) input).buffer;
+      public ByteBuffer apply(Record input) {
+        return input.buffer;
       }
     });
-    return buffers.iterator();
   }
 
   @Override
@@ -110,20 +111,21 @@ public class JavaWriteAheadLogSuite extends WriteAheadLog {
     WriteAheadLog wal = WriteAheadLogUtils.createLogForDriver(conf, null, null);
 
     String data1 = "data1";
-    WriteAheadLogRecordHandle handle = wal.write(ByteBuffer.wrap(data1.getBytes()), 1234);
+    WriteAheadLogRecordHandle handle =
+        wal.write(ByteBuffer.wrap(data1.getBytes(StandardCharsets.UTF_8)), 1234);
     Assert.assertTrue(handle instanceof JavaWriteAheadLogSuiteHandle);
-    Assert.assertTrue(new String(wal.read(handle).array()).equals(data1));
+    Assert.assertEquals(new String(wal.read(handle).array(), StandardCharsets.UTF_8), data1);
 
-    wal.write(ByteBuffer.wrap("data2".getBytes()), 1235);
-    wal.write(ByteBuffer.wrap("data3".getBytes()), 1236);
-    wal.write(ByteBuffer.wrap("data4".getBytes()), 1237);
+    wal.write(ByteBuffer.wrap("data2".getBytes(StandardCharsets.UTF_8)), 1235);
+    wal.write(ByteBuffer.wrap("data3".getBytes(StandardCharsets.UTF_8)), 1236);
+    wal.write(ByteBuffer.wrap("data4".getBytes(StandardCharsets.UTF_8)), 1237);
     wal.clean(1236, false);
 
-    java.util.Iterator<java.nio.ByteBuffer> dataIterator = wal.readAll();
-    ArrayList<String> readData = new ArrayList<String>();
+    Iterator<ByteBuffer> dataIterator = wal.readAll();
+    List<String> readData = new ArrayList<>();
     while (dataIterator.hasNext()) {
-      readData.add(new String(dataIterator.next().array()));
+      readData.add(new String(dataIterator.next().array(), StandardCharsets.UTF_8));
     }
-    Assert.assertTrue(readData.equals(Arrays.asList("data3", "data4")));
+    Assert.assertEquals(readData, Arrays.asList("data3", "data4"));
   }
 }