Customized Serialization

Customized Serialization

During default Serialization there may be a chance of loss of information because of transient variables.

package com.ashok.files;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

/**
 * 
 * @author ashok.mariyala
 *
 */
class Dog implements Serializable {
   Cat c = new Cat();
}
class Cat {
   String name = "Welcome to Waytoeasylearn.com";
}

public class MySerialization {
   public static void main(String arg[]) throws Exception {
      Dog d = new Dog();
      FileOutputStream fos = new FileOutputStream("ashok.ser");
      ObjectOutputStream oos = new ObjectOutputStream(fos);
      oos.writeObject(d);
      FileInputStream fis = new FileInputStream("ashok.ser");
      ObjectInputStream ois = new ObjectInputStream(fis);
      Dog d1 = (Dog) ois.readObject();
      System.out.println(d1.c.r.j);
   }
}

Output

Exception in thread "main" java.io.NotSerializableException: com.ashok.files.Cat

We can implement customized Serialization by using the following two methods.

private void writeObject(OutputStream os)throws Exception {
   ..........
   ..........
}

This method will be executed automatically by the JVM at the time of Serialization.

private void readObject(InputStream is)throws Exception {
   ..........
   ..........
}

This method will be executed automatically by the JVM at the time of deSerialization.

package com.ashok.files;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
/**
 * 
 * @author ashok.mariyala
 *
 */
class Dog implements Serializable {
   transient Cat c = new Cat();

   private void writeObject(ObjectOutputStream os) throws IOException {
      int x = c.j;
      os.writeInt(x);
   }

   private void readObject(ObjectInputStream is) throws IOException, ClassNotFoundException {
      is.defaultReadObject();
      int k = is.readInt();
      c = new Cat();
      c.j = k;
   }
}

class Cat {
   int j = 100;
}

class SerializeDemo {
   public static void main(String arg[]) throws Exception {
      Dog d = new Dog();
      System.out.println("Before Serialization:" + d.c.j);
      FileOutputStream fos = new FileOutputStream("ashok.ser");
      ObjectOutputStream oos = new ObjectOutputStream(fos);
      oos.writeObject(d);
      FileInputStream fis = new FileInputStream("ashok.ser");
      ObjectInputStream ois = new ObjectInputStream(fis);
      Dog d1 = (Dog) ois.readObject();
      System.out.println(d1.c.j);
   }
}

Output

100
Customized Serialization


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