Fix for flatmap

streaming/src/main/scala/spark/streaming/api/java/JavaDStreamLike.scala

@@ -78,10 +78,10 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This]] extends Serializable
    * Return a new DStream by applying a function to all elements of this DStream,
    * and then flattening the results
    */
-  def flatMap[K, V](f: PairFlatMapFunction[T, K, V]): JavaPairDStream[K, V] = {
+  def flatMap[K2, V2](f: PairFlatMapFunction[T, K2, V2]): JavaPairDStream[K2, V2] = {
     import scala.collection.JavaConverters._
     def fn = (x: T) => f.apply(x).asScala
-    def cm = implicitly[ClassManifest[AnyRef]].asInstanceOf[ClassManifest[Tuple2[K, V]]]
+    def cm = implicitly[ClassManifest[AnyRef]].asInstanceOf[ClassManifest[Tuple2[K2, V2]]]
     new JavaPairDStream(dstream.flatMap(fn)(cm))(f.keyType(), f.valueType())
   }
 

streaming/src/test/java/spark/streaming/JavaAPISuite.java

@@ -562,6 +562,48 @@ public class JavaAPISuite implements Serializable {
     Assert.assertEquals(expected, result);
   }
 
+  @Test
+  public void testPairToPairFlatMapWithChangingTypes() { // Maps pair -> pair
+    List<List<Tuple2<String, Integer>>> inputData = Arrays.asList(
+        Arrays.asList(
+            new Tuple2<String, Integer>("hi", 1),
+            new Tuple2<String, Integer>("ho", 2)),
+        Arrays.asList(
+            new Tuple2<String, Integer>("hi", 1),
+            new Tuple2<String, Integer>("ho", 2)));
+
+    List<List<Tuple2<Integer, String>>> expected = Arrays.asList(
+        Arrays.asList(
+            new Tuple2<Integer, String>(1, "h"),
+            new Tuple2<Integer, String>(1, "i"),
+            new Tuple2<Integer, String>(2, "h"),
+            new Tuple2<Integer, String>(2, "o")),
+        Arrays.asList(
+            new Tuple2<Integer, String>(1, "h"),
+            new Tuple2<Integer, String>(1, "i"),
+            new Tuple2<Integer, String>(2, "h"),
+            new Tuple2<Integer, String>(2, "o")));
+
+    JavaDStream<Tuple2<String, Integer>> stream =
+        JavaTestUtils.attachTestInputStream(ssc, inputData, 1);
+    JavaPairDStream<String, Integer> pairStream = JavaPairDStream.fromJavaDStream(stream);
+    JavaPairDStream<Integer, String> flatMapped = pairStream.flatMap(
+      new PairFlatMapFunction<Tuple2<String, Integer>, Integer, String>() {
+      @Override
+      public Iterable<Tuple2<Integer, String>> call(Tuple2<String, Integer> in) throws Exception {
+        List<Tuple2<Integer, String>> out = new LinkedList<Tuple2<Integer, String>>();
+        for (Character s: in._1().toCharArray()) {
+          out.add(new Tuple2<Integer, String>(in._2(), s.toString()));
+        }
+        return out;
+      }
+    });
+    JavaTestUtils.attachTestOutputStream(flatMapped);
+    List<List<Tuple2<String, Integer>>> result = JavaTestUtils.runStreams(ssc, 2, 2);
+
+    Assert.assertEquals(expected, result);
+  }
+
   @Test
   public void testPairGroupByKey() {
     List<List<Tuple2<String, String>>> inputData = stringStringKVStream;