After some reading I found This is the most easiest way to transfer data in client-server application in Java.

This is the normal way of a Sever Side of the application;

import java.net.ServerSocket;    

import java.net.Socket;    

import java.io.IOException;    

import java.io.InputStreamReader;    

import java.io.BufferedReader;    

import java.lang.System;        

public class server    {      

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

  ServerSocket s = new ServerSocket (2000);        

  Socket sock;        

  BufferedReader datain;            

  System.out.println ("Server starting ...");        

  sock = s.accept ();            

  datain = new BufferedReader (new InputStreamReader(sock.getInputStream ()));        

  System.out.println (datain.readLine ());            

  sock.close ();        

  s.close ();      

}    

}

This is the normal way of a Client Side of the application;

import java.net.Socket;    
import java.net.InetAddress;    
import java.io.IOException;    
import java.io.OutputStreamWriter;    
import java.io.BufferedWriter;    
import java.lang.System;        
public class client{      
public static void main (String args[])throws IOException {        
  Socket sock = new Socket (InetAddress.getLocalHost (), 2000);        
  BufferedWriter dataout;        
  String Message = "Howdy!";            
  System.out.println ("Sending "+ Message + " ...");            
  dataout = new BufferedWriter (new OutputStreamWriter (sock.getOutputStream ()));        
  dataout.write (Message, 0, Message.length ());        
  dataout.flush ();            
  sock.close ();      
}    
}


But think a situation where we have to transfer set of data at a time. For a example like details of a
Student registration. So When we use normal method we have to send data fields as messages. Example name 
one time , age at one time so and so But we can use java class to over come this problem.


Hear is a example.
Server Side;



import java.io.*;

import java.util.Date;

public class SaveDate {

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

   FileOutputStream fos = new FileOutputStream("date.out");

   ObjectOutputStream oos = new ObjectOutputStream(fos);

  Student st = new Student();

   oos.writeObject(st);

  oos.flush();

  oos.close();

  fos.close();

}
}
Client Side ;

import java.io.*;

import java.util.Date;

public class ReadDate {

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

   FileInputStream fis = new FileInputStream("date.out");

   ObjectInputStream ois = new ObjectInputStream(fis);

   Student st = (Student) ois.readObject();

   System.out.println("The Name is:"+st.name);

   System.out.println("The Index is:"+st.index);

   ois.close();

   fis.close();

}
}
The Student Class;


public Students implements Serializble{
  String name;
  String index
}