1 /*
   2  * Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 import java.lang.reflect.*;
  26 import sun.hotspot.WhiteBox;
  27 
  28 /*
  29  * Lock the 'value' field of a known shared string, java.lang.Object
  30  */
  31 public class LockStringValueTest {
  32     public static void main(String args[]) {
  33         String s = "LiveOak";
  34         WhiteBox wb = WhiteBox.getWhiteBox();
  35 
  36         if (wb.areSharedStringsIgnored()) {
  37             System.out.println("The shared strings are ignored");
  38             System.out.println("LockStringValueTest: PASS");
  39             return;
  40         }
  41 
  42         if (!wb.isShared(s)) {
  43             throw new RuntimeException("LockStringValueTest Failed: String is not shared.");
  44         }
  45 
  46         Class c = s.getClass();
  47         try {
  48             Field f = c.getDeclaredField("value");
  49             f.setAccessible(true);
  50             Object v = f.get(s);
  51             lock(v);
  52         } catch (NoSuchFieldException nfe) {
  53         } catch (IllegalAccessException iae) {}
  54     }
  55 
  56     public static void lock(Object o) {
  57         synchronized (o) {
  58             System.out.println("LockStringValueTest: PASS");
  59         }
  60     }
  61 }