Controlling serialization by adding your own : Object Serialization « File « Java Tutorial

1. Java Tutorial
2. File
3. Object Serialization

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class MainClass {

  public static void main(String[] args) throws IOException, ClassNotFoundException {
    MyBean sc = new MyBean("Test1", "Test2");
    System.out.println("Before:\n" + sc);

    ByteArrayOutputStream buf = new ByteArrayOutputStream();
    ObjectOutputStream o = new ObjectOutputStream(buf);
    o.writeObject(sc);

    ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(buf.toByteArray()));
    MyBean sc2 = (MyBean) in.readObject();
    System.out.println("After:\n" + sc2);
  }
}

class MyBean implements Serializable {
  private String a;

  private transient String b;

  public MyBean(String aa, String bb) {
    a = "Not Transient: " + aa;
    b = "Transient: " + bb;
  }

  public String toString() {
    return a + "\n" + b;
  }

  private void writeObject(ObjectOutputStream stream) throws IOException {
    stream.defaultWriteObject();
    stream.writeObject(b);
  }

  private void readObject(ObjectInputStream stream) throws IOException, ClassNotFoundException {
    stream.defaultReadObject();
    b = (String) stream.readObject();
  }
}
/*
*/

Before:
Not Transient: Test1
Transient: Test2
After:
Not Transient: Test1
Transient: Test2