1 /*
   2  * Copyright (c) 2016, 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 package optionsvalidation;
  25 
  26 import java.lang.ref.WeakReference;
  27 
  28 class JVMStartup {
  29     private static volatile WeakReference<Object> weakRef;
  30 
  31     private static synchronized void createWeakRef() {
  32         Object o = new Object();
  33         weakRef = new WeakReference<>(o);
  34     }
  35 
  36     /* Simple method to test that java start-up. Used for testing options. */
  37     public static void main(String[] args) throws Exception {
  38         byte[] garbage = new byte[8192];
  39         int i = 0;
  40         createWeakRef();
  41         do {
  42             garbage = new byte[8192];
  43             i++;
  44             /* Initiate GC after 5 iterations */
  45             if (i > 5) {
  46                 System.gc();
  47             }
  48         } while(weakRef.get() != null);
  49         System.out.println("Java start-up!");
  50     }
  51 }