Customizing Java Serialization .

package app;

import java.awt.Color;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

public class Rectangle implements java.io.Serializable {

  private int length;
  private int width;
  // This member variable will not be Serialized as it is transient.
  transient private Color color;

  public Rectangle() {
  }

  public Rectangle(int width, int length, Color color) {
    this.length = length;
    this.width = width;
    this.color = color;
  }

  private void readObject(ObjectInputStream input)
                         throws IOException, ClassNotFoundException {
    // deserialize the non-transient data members first;
    input.defaultReadObject();
    // Read the color
    setColor((Color)input.readObject());
  }
  private void writeObject(ObjectOutputStream output)
                         throws IOException, ClassNotFoundException {
    // serialize the non-transient data members first;
    output.defaultWriteObject();
    // Write the color
    output.writeObject(color);
  }

  @Override
  public String toString() {
    return " width: " + width + " length: " + length + " color: " + color;
  }

  public int getLength() {
    return length;
  }

  public void setLength(int length) {
    this.length = length;
  }

  public int getWidth() {
    return width;
  }

  public void setWidth(int width) {
    this.width = width;
  }

  public Color getColor() {
    return color;
  }

  public void setColor(Color color) {
    this.color = color;
  }
}

package app;

import java.awt.Color;
import java.io.*;

public class WriteObj {
  public static void main(String args[]) {
    Rectangle rect = new Rectangle(25, 60, Color.blue);
    ObjectOutputStream out = null;
    try {
      out = new ObjectOutputStream(new FileOutputStream("Rectangle.ser"));
      out.writeObject(rect);
      System.out.println("Wrote Rectangle with \"" + rect + "\" to file");
    }
    catch (IOException e) {
      System.err.println("Error writing object: " + e.getMessage());
    }
    finally {
      try {
        out.close();
      }
      catch (IOException e) {
        System.err.println(e.getMessage());
      }
    }
  }
}

package app;

import java.io.*;

public class ReadObj {
  public static void main(String args[]) {
    ObjectInputStream in = null;
    try {
      in = new ObjectInputStream(
        new FileInputStream("Rectangle.ser"));
      Rectangle rect = (Rectangle) in.readObject();
      System.out.println("Read Rectangle with \"" + rect + "\" from file");
    }
    catch (ClassCastException e) {
      System.err.println("Error casting object to a Rectangle");
    }
    catch (ClassNotFoundException e) {
      System.err.println("Class not found");
    }
    catch (IOException e) {
      System.err.println("Error reading object: " + e.getMessage());
    }
    finally {
      try {
        in.close();
      }
      catch (IOException e) {
        System.err.println(e.getMessage());
      }
    }
  }
}