Name: rlT66838 Date: 07/17/97


Altough the documentation mentions that one can replace
an object with the null value in the replaceObject method
of ObjectOutputStream, doing this always results in a
NullPointerException at ObjectOutputStream.writeObject(Object)

Here is some sample code :
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import java.io.*;

class A { }

class MyObjectOutputStream extends ObjectOutputStream {
  public MyObjectOutputStream(OutputStream out) throws IOException {
    super(out);
    enableReplaceObject(true);
  }
  protected Object replaceObject(Object obj) throws IOException {
    if(obj instanceof A) return null;
    else return obj;
  }
}

class Main {
  public static void main(String argv[]) {
    try {
      A a = new A();
    
      MyObjectOutputStream out = new MyObjectOutputStream(new FileOutputStream("test"));
      out.writeObject(a);
      out.flush();
      out.close();
    } catch(Exception e) {
      e.printStackTrace();
    }
  }
}

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