SPARK-1095 add explicit return types to APIs.

Author: ScrapCodes

core/src/main/scala/org/apache/spark/api/java/JavaRDD.scala

@@ -126,7 +126,7 @@ class JavaRDD[T](val rdd: RDD[T])(implicit val classTag: ClassTag[T])
   def subtract(other: JavaRDD[T], p: Partitioner): JavaRDD[T] =
     wrapRDD(rdd.subtract(other, p))
 
-  def generator = rdd.generator
+  def generator: String = rdd.generator
 
   override def toString = rdd.toString
 

core/src/main/scala/org/apache/spark/api/java/JavaRDDLike.scala

@@ -74,7 +74,7 @@ trait JavaRDDLike[T, This <: JavaRDDLike[T, This]] extends Serializable {
    * of the original partition.
    */
   def mapPartitionsWithIndex[R: ClassTag](
-      f: JFunction2[Int, java.util.Iterator[T], java.util.Iterator[R]],
+      f: JFunction2[Integer, java.util.Iterator[T], java.util.Iterator[R]],
       preservesPartitioning: Boolean = false): JavaRDD[R] =
     new JavaRDD(rdd.mapPartitionsWithIndex(((a,b) => f(a,asJavaIterator(b))),
         preservesPartitioning))

core/src/main/scala/org/apache/spark/api/java/JavaSparkContext.scala

@@ -17,6 +17,7 @@
 
 package org.apache.spark.api.java
 
+import java.util
 import java.util.{Map => JMap}
 
 import scala.collection.JavaConversions
@@ -92,23 +93,23 @@ class JavaSparkContext(val sc: SparkContext) extends JavaSparkContextVarargsWork
 
   private[spark] val env = sc.env
 
-  def isLocal = sc.isLocal
+  def isLocal: java.lang.Boolean = sc.isLocal
 
-  def sparkUser = sc.sparkUser
+  def sparkUser: String = sc.sparkUser
 
-  def master = sc.master
+  def master: String = sc.master
 
-  def appName = sc.appName
+  def appName: String = sc.appName
 
-  def jars = JavaConversions.seqAsJavaList(sc.jars)
+  def jars: util.List[String] = sc.jars
 
-  def startTime = sc.startTime
+  def startTime: java.lang.Long = sc.startTime
 
   /** Default level of parallelism to use when not given by user (e.g. parallelize and makeRDD). */
-  def defaultParallelism = sc.defaultParallelism
+  def defaultParallelism: Integer = sc.defaultParallelism
 
   /** Default min number of partitions for Hadoop RDDs when not given by user */
-  def defaultMinSplits = sc.defaultMinSplits
+  def defaultMinSplits: Integer = sc.defaultMinSplits
 
   /** Distribute a local Scala collection to form an RDD. */
   def parallelize[T](list: java.util.List[T], numSlices: Int): JavaRDD[T] = {