What is the use of transient keyword in java?

 At the time of Serialization if we don't want to serialize the value of partitcular variable to meet the security contraint we have to declare those variable with transient keyword.

At the time of Serialization JVM ignores original value of transient variable and saves default value.


class T {

transient int a; // will not persist
int b; // will persist

}

Example:
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.Date;
public class Logon implements Serializable {

private Date date = new Date();

private String username;

private transient String password;

public Logon(String name, String pwd) {

username = name;

password = pwd;

}

public String toString() {

String pwd = (password == null) ? "(n/a)" : password;

return "logon info: \n username: " + username + "\n date: " + date

+ "\n password: " + pwd;

}

public static void main(String[] args) throws Exception {

Logon a = new Logon("Hulk", "myLittlePony");

System.out.println("logon a = " + a);

ObjectOutputStream o = new ObjectOutputStream(new FileOutputStream(

"Logon.out"));

o.writeObject(a);

o.close();

Thread.sleep(1000); // Delay for 1 second

// Now get them back:

ObjectInputStream in = new ObjectInputStream(new FileInputStream(

"Logon.out"));

System.out.println("Recovering object at " + new Date());

a = (Logon) in.readObject();

System.out.println("logon a = " + a);

}

}