Java examples, tests for KMeans and ALS

- Changes ALS to accept RDD[Rating] instead of (Int, Int, Double) making it
  easier to call from Java
- Renames class methods from `train` to `run` to enable static methods to be
  called from Java.
- Add unit tests which check if both static / class methods can be called.
- Also add examples which port the main() function in ALS, KMeans to the
  examples project.

Couple of minor changes to existing code:
- Add a toJavaRDD method in RDD to convert scala RDD to java RDD easily
- Workaround a bug where using double[] from Java leads to class cast exception in
  KMeans init

1 files changed, 5 insertions, 0 deletions

diff --git a/core/src/main/scala/spark/RDD.scala b/core/src/main/scala/spark/RDD.scala
index ca7cdd622a..160b3e9d83 100644
--- a/core/src/main/scala/spark/RDD.scala
+++ b/core/src/main/scala/spark/RDD.scala
@@ -31,6 +31,7 @@ import org.apache.hadoop.mapred.TextOutputFormat
 
 import it.unimi.dsi.fastutil.objects.{Object2LongOpenHashMap => OLMap}
 
+import spark.api.java.JavaRDD
 import spark.broadcast.Broadcast
 import spark.Partitioner._
 import spark.partial.BoundedDouble
@@ -950,4 +951,8 @@ abstract class RDD[T: ClassManifest](
     id,
     origin)
 
+  def toJavaRDD() : JavaRDD[T] = {
+    new JavaRDD(this)(elementClassManifest)
+  }
+
 }