// This example is from the book Developing Java Beans by Robert Englander. 
// Copyright (c) 1997 O'Reilly & Associates.
// You may study, use, modify, and distribute this example for any purpose.
// This example is provided WITHOUT WARRANTY either expressed or implied.

// Chapter 5 -- The Example9 class and associated classes

import java.io.*;

class AA implements java.io.Externalizable
{
   protected int a = 0;

   public void writeExternal(ObjectOutput stream)
               throws java.io.IOException
   {
      System.out.println("writeExternal called for class AA");
      stream.writeInt(a);
   }
  
   public void readExternal(ObjectInput stream)
               throws java.io.IOException
   {
      System.out.println("readExternal called for class AA");
      a = stream.readInt();
   }


   public AA()
   {
   }
} 

class BB extends AA
{
   protected int b = 0;

   public void writeExternal(ObjectOutput stream)
               throws java.io.IOException
   {
      super.writeExternal(stream);
      System.out.println("writeExternal called for class BB");
      stream.writeInt(b);
   }

   public void readExternal(ObjectInput stream)
               throws java.io.IOException
   {
      super.readExternal(stream);
      System.out.println("readExternal called for class BB");
      b = stream.readInt();
   }

   public BB()
   {
      super();
   }
}

class CC extends BB
{
   protected int c = 0;

   public void writeExternal(ObjectOutput stream)
               throws java.io.IOException
   {
      super.writeExternal(stream);
      System.out.println("writeExternal called for class CC");
      stream.writeInt(c);
   }

   public void readExternal(ObjectInput stream)
               throws java.io.IOException
   {
      super.readExternal(stream);
      System.out.println("readExternal called for class CC");
      c = stream.readInt();
   }

   public CC()
   {
      super();
   }
}

public class Example9
{
   // the application entry point
   public static void main(String[] args)
   {
      // create an instance of class CC
      CC c = new CC();
      try
      {
         FileOutputStream f = new FileOutputStream("Example9.tmp");
         ObjectOutputStream s = new ObjectOutputStream(f);
         s.writeObject(c);
         s.flush();
      }
      catch (Exception e)
      {
         System.out.println(e);
      }

      try
      {
         FileInputStream f = new FileInputStream("Example9.tmp");
         ObjectInputStream s = new ObjectInputStream(f);
         c = (CC)s.readObject();
      }
      catch (Exception e)
      {
         System.out.println(e);
      }

   }
}