Adding flatMap

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

@@ -64,6 +64,27 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This]] extends Serializable
     new JavaPairDStream(dstream.map(f)(cm))(f.keyType(), f.valueType())
   }
 
+  /**
+   * Return a new DStream by applying a function to all elements of this DStream,
+   * and then flattening the results
+   */
+  def flatMap[U](f: FlatMapFunction[T, U]): JavaDStream[U] = {
+    import scala.collection.JavaConverters._
+    def fn = (x: T) => f.apply(x).asScala
+    new JavaDStream(dstream.flatMap(fn)(f.elementType()))(f.elementType())
+  }
+
+  /**
+   * 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] = {
+    import scala.collection.JavaConverters._
+    def fn = (x: T) => f.apply(x).asScala
+    def cm = implicitly[ClassManifest[AnyRef]].asInstanceOf[ClassManifest[Tuple2[K, V]]]
+    new JavaPairDStream(dstream.flatMap(fn)(cm))(f.keyType(), f.valueType())
+  }
+
     /**
    * Return a new DStream in which each RDD is generated by applying mapPartitions() to each RDDs
    * of this DStream. Applying mapPartitions() to an RDD applies a function to each partition
@@ -151,4 +172,12 @@ trait JavaDStreamLike[T, This <: JavaDStreamLike[T, This]] extends Serializable
       transformFunc.call(new JavaRDD[T](in), time).rdd
     dstream.transform(scalaTransform(_, _))
   }
+
+  /**
+   * Enable periodic checkpointing of RDDs of this DStream
+   * @param interval Time interval after which generated RDD will be checkpointed
+   */
+  def checkpoint(interval: Duration) = {
+    dstream.checkpoint(interval)
+  }
 }

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

@@ -11,10 +11,7 @@ import org.junit.Test;
 import scala.Tuple2;
 import spark.HashPartitioner;
 import spark.api.java.JavaRDD;
-import spark.api.java.function.FlatMapFunction;
-import spark.api.java.function.Function;
-import spark.api.java.function.Function2;
-import spark.api.java.function.PairFunction;
+import spark.api.java.function.*;
 import spark.storage.StorageLevel;
 import spark.streaming.api.java.JavaDStream;
 import spark.streaming.api.java.JavaPairDStream;
@@ -308,6 +305,82 @@ public class JavaAPISuite implements Serializable {
     assertOrderInvariantEquals(expected, result);
   }
 
+  @Test
+  public void testFlatMap() {
+    List<List<String>> inputData = Arrays.asList(
+        Arrays.asList("go", "giants"),
+        Arrays.asList("boo", "dodgers"),
+        Arrays.asList("athletics"));
+
+    List<List<String>> expected = Arrays.asList(
+        Arrays.asList("g","o","g","i","a","n","t","s"),
+        Arrays.asList("b", "o", "o", "d","o","d","g","e","r","s"),
+        Arrays.asList("a","t","h","l","e","t","i","c","s"));
+
+    JavaDStream stream = JavaTestUtils.attachTestInputStream(sc, inputData, 1);
+    JavaDStream flatMapped = stream.flatMap(new FlatMapFunction<String, String>() {
+      @Override
+      public Iterable<String> call(String x) {
+        return Lists.newArrayList(x.split("(?!^)"));
+      }
+    });
+    JavaTestUtils.attachTestOutputStream(flatMapped);
+    List<List<String>> result = JavaTestUtils.runStreams(sc, 3, 3);
+
+    assertOrderInvariantEquals(expected, result);
+  }
+
+  @Test
+  public void testPairFlatMap() {
+    List<List<String>> inputData = Arrays.asList(
+        Arrays.asList("giants"),
+        Arrays.asList("dodgers"),
+        Arrays.asList("athletics"));
+
+    List<List<Tuple2<Integer, String>>> expected = Arrays.asList(
+        Arrays.asList(
+            new Tuple2<Integer, String>(6, "g"),
+            new Tuple2<Integer, String>(6, "i"),
+            new Tuple2<Integer, String>(6, "a"),
+            new Tuple2<Integer, String>(6, "n"),
+            new Tuple2<Integer, String>(6, "t"),
+            new Tuple2<Integer, String>(6, "s")),
+        Arrays.asList(
+            new Tuple2<Integer, String>(7, "d"),
+            new Tuple2<Integer, String>(7, "o"),
+            new Tuple2<Integer, String>(7, "d"),
+            new Tuple2<Integer, String>(7, "g"),
+            new Tuple2<Integer, String>(7, "e"),
+            new Tuple2<Integer, String>(7, "r"),
+            new Tuple2<Integer, String>(7, "s")),
+        Arrays.asList(
+            new Tuple2<Integer, String>(9, "a"),
+            new Tuple2<Integer, String>(9, "t"),
+            new Tuple2<Integer, String>(9, "h"),
+            new Tuple2<Integer, String>(9, "l"),
+            new Tuple2<Integer, String>(9, "e"),
+            new Tuple2<Integer, String>(9, "t"),
+            new Tuple2<Integer, String>(9, "i"),
+            new Tuple2<Integer, String>(9, "c"),
+            new Tuple2<Integer, String>(9, "s")));
+
+    JavaDStream stream = JavaTestUtils.attachTestInputStream(sc, inputData, 1);
+    JavaPairDStream flatMapped = stream.flatMap(new PairFlatMapFunction<String, Integer, String>() {
+      @Override
+      public Iterable<Tuple2<Integer, String>> call(String in) throws Exception {
+        List<Tuple2<Integer, String>> out = Lists.newArrayList();
+        for (String letter: in.split("(?!^)")) {
+          out.add(new Tuple2<Integer, String>(in.length(), letter));
+        }
+        return out;
+      }
+    });
+    JavaTestUtils.attachTestOutputStream(flatMapped);
+    List<List<Tuple2<Integer, String>>> result = JavaTestUtils.runStreams(sc, 3, 3);
+
+    Assert.assertEquals(expected, result);
+  }
+
   @Test
   public void testUnion() {
     List<List<Integer>> inputData1 = Arrays.asList(