6636369: sun.awt.datatransfer.DataTransferer contains double-check idiom

Summary: double-check has been removed
Reviewed-by: dav

src/share/classes/sun/awt/datatransfer/DataTransferer.java

 /*
- * Copyright 2000-2007 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright 2000-2008 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -270,17 +270,16 @@ public abstract class DataTransferer {
      * instead, null will be returned.
      */
     public static DataTransferer getInstance() {
-        if (transferer == null) {
         synchronized (DataTransferer.class) {
             if (transferer == null) {
-                    final String name = SunToolkit.
-                        getDataTransfererClassName();
+                final String name = SunToolkit.getDataTransfererClassName();
                 if (name != null) {
-                        PrivilegedAction action = new PrivilegedAction() {
-                          public Object run() {
+                    PrivilegedAction<DataTransferer> action = new PrivilegedAction<DataTransferer>()
+                    {
+                      public DataTransferer run() {
                           Class cls = null;
                           Method method = null;
-                              Object ret = null;
+                          DataTransferer ret = null;
 
                           try {
                               cls = Class.forName(name);
@@ -298,8 +297,7 @@ public abstract class DataTransferer {
                           }
                           if (cls != null) {
                               try {
-                                      method = cls.getDeclaredMethod
-                                          ("getInstanceImpl");
+                                  method = cls.getDeclaredMethod("getInstanceImpl");
                                   method.setAccessible(true);
                               } catch (NoSuchMethodException e) {
                                   e.printStackTrace();
@@ -311,7 +309,7 @@ public abstract class DataTransferer {
                           }
                           if (method != null) {
                               try {
-                                      ret = method.invoke(null);
+                                  ret = (DataTransferer) method.invoke(null);
                               } catch (InvocationTargetException e) {
                                   e.printStackTrace();
                                   throw new AWTError("Cannot instantiate DataTransferer: " + name);
@@ -323,9 +321,7 @@ public abstract class DataTransferer {
                           return ret;
                       }
                     };
-                        transferer = (DataTransferer)
-                            AccessController.doPrivileged(action);
-                    }
+                    transferer = AccessController.doPrivileged(action);
                 }
             }
         }