1 /*
   2  * Copyright (c) 1997, 1998, 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 /* @test
  25  * @bug 4065313
  26  * @summary Ensure that it is okay to replace an object with null.
  27  */
  28 import java.io.*;
  29 
  30 class A { }
  31 
  32 class MyObjectOutputStream extends ObjectOutputStream {
  33   public MyObjectOutputStream(OutputStream out) throws IOException {
  34     super(out);
  35     enableReplaceObject(true);
  36   }
  37   protected Object replaceObject(Object obj) throws IOException {
  38     if(obj instanceof A) return null;
  39     else return obj;
  40   }
  41 }
  42 
  43 public class ReplaceWithNull {
  44     public static void main(String args[]) throws IOException {
  45         A a = new A();
  46 
  47         MyObjectOutputStream out =
  48             new MyObjectOutputStream(new ByteArrayOutputStream());
  49         out.writeObject(a);     //raised NullPointerException.
  50         out.close();
  51     }
  52 }