refactor

Author: Davies Liu

core/src/main/scala/org/apache/spark/api/python/PythonRDD.scala

@@ -24,6 +24,7 @@ import java.util.{List => JList, ArrayList => JArrayList, Map => JMap, Collectio
 import org.apache.spark.input.PortableDataStream
 
 import scala.collection.JavaConversions._
+import scala.collection.JavaConverters._
 import scala.collection.mutable
 import scala.language.existentials
 
@@ -762,11 +763,7 @@ private[spark] object PythonRDD extends Logging {
    * A helper to convert java.util.List[Double] into Array[Double]
    */
   def listToArrayDouble(list: JList[Double]): Array[Double] = {
-    val r = new Array[Double](list.size)
-    list.zipWithIndex.foreach {
-      case (v, i) => r(i) = v
-    }
-    r
+    list.asScala.toArray
   }
 }