diff --git a/core/src/main/scala/org/apache/spark/executor/Executor.scala b/core/src/main/scala/org/apache/spark/executor/Executor.scala
index bce2085491f46..7222c56e61788 100644
--- a/core/src/main/scala/org/apache/spark/executor/Executor.scala
+++ b/core/src/main/scala/org/apache/spark/executor/Executor.scala
@@ -291,7 +291,7 @@ private[spark] class Executor(
    * Create a ClassLoader for use in tasks, adding any JARs specified by the user or any classes
    * created by the interpreter to the search path
    */
-  private def createClassLoader(): AddableURLClassLoader = {
+  private def createClassLoader(): MutableURLClassLoader = {
     val loader = this.getClass.getClassLoader
 
     // For each of the jars in the jarSet, add them to the class loader.
diff --git a/core/src/main/scala/org/apache/spark/executor/ExecutorURLClassLoader.scala b/core/src/main/scala/org/apache/spark/executor/ExecutorURLClassLoader.scala
index 005e360affd1f..f60e37ec814b6 100644
--- a/core/src/main/scala/org/apache/spark/executor/ExecutorURLClassLoader.scala
+++ b/core/src/main/scala/org/apache/spark/executor/ExecutorURLClassLoader.scala
@@ -32,9 +32,9 @@ private[spark] trait MutableURLClassLoader extends ClassLoader {
 }
 
 private[spark] class ChildExecutorURLClassLoader(urls: Array[URL], parent: ClassLoader)
-  extends ClassLoader with AddableURLClassLoader {
+  extends ClassLoader with MutableURLClassLoader {
 
-  private val userClassLoader = new URLClassLoader(urls, null){
+  private object userClassLoader extends URLClassLoader(urls, null){
     override def addURL(url: URL) {
       super.addURL(url)
     }
@@ -65,7 +65,7 @@ private[spark] class ChildExecutorURLClassLoader(urls: Array[URL], parent: Class
 }
 
 private[spark] class ExecutorURLClassLoader(urls: Array[URL], parent: ClassLoader)
-  extends URLClassLoader(urls, parent) with AddableURLClassLoader {
+  extends URLClassLoader(urls, parent) with MutableURLClassLoader {
 
   override def addURL(url: URL) {
     super.addURL(url)
diff --git a/core/src/main/scala/org/apache/spark/util/ParentClassLoader.scala b/core/src/main/scala/org/apache/spark/util/ParentClassLoader.scala
index 354ea78eec5c7..3abc12681fe9a 100644
--- a/core/src/main/scala/org/apache/spark/util/ParentClassLoader.scala
+++ b/core/src/main/scala/org/apache/spark/util/ParentClassLoader.scala
@@ -15,23 +15,18 @@
  * limitations under the License.
  */
 
-package org.apache.spark.util;
+package org.apache.spark.util
 
 /**
  * A class loader which makes findClass accesible to the child
  */
-public class ParentClassLoader extends ClassLoader {
-    public ParentClassLoader(ClassLoader myParent) {
-	super(myParent);
-    }
+private[spark] class ParentClassLoader(parent: ClassLoader) extends ClassLoader(parent) {
 
-    @Override
-    public Class<?> findClass(String name) throws ClassNotFoundException {
-	return super.findClass(name);
-    }
+  override def findClass(name: String) = {
+    super.findClass(name)
+  }
 
-    @Override
-    public Class<?> loadClass(String name) throws ClassNotFoundException {
-	return super.loadClass(name);
-    }
+  override def loadClass(name: String): Class[_] = {
+    super.loadClass(name)
+  }
 }