Wirte your own serialization code : Serialization « File « SCJP

1. SCJP
2. File
3. Serialization

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

class MyClass implements Serializable {
  private String id;

  protected int n;

  transient byte notMe;

  private void writeObject(ObjectOutputStream oos) throws IOException {
    oos.writeUTF("The password is swordfish");
    oos.defaultWriteObject();
  }

  private void readObject(ObjectInputStream ois) throws IOException, ClassNotFoundException {
    String password = ois.readUTF();
    if (!password.equals("The password is swordfish"))
      throw new SecurityException("Bad password");
    ois.defaultReadObject();
  }
}