Program for Client - Server communication to perform Echo Opreration using UDP in Java

     The DatagramSocket object is used to establish communication between Client and Server.

client

import java.io.*;

import java.net.*;

import java.util.*;

class Client1

{

            public static void main(String args[])

            {

            try

            {

                        DatagramSocket client=new DatagramSocket();

                        InetAddress addr=InetAddress.getByName("127.0.0.1");

                        byte[] sendbyte=new byte[1024];

                        byte[] receivebyte=new byte[1024];

                        BufferedReader in=new BufferedReader(new InputStreamReader(System.in));

                        System.out.println("Enter the String:");

                        String str=in.readLine();

                        sendbyte=str.getBytes();

                        DatagramPacket sender=new DatagramPacket(sendbyte,sendbyte.length,addr,1309);

                        client.send(sender);

                        DatagramPacket receiver=new DatagramPacket(receivebyte,receivebyte.length);

                        client.receive(receiver);

                        String s=new String(receiver.getData());

                        System.out.println(s.trim());   

                        client.close();

            }

            catch(Exception e)

            {

                        System.out.println(e);

            }

            }

}

Server

import java.io.*;

import java.net.*;

import java.util.*;

class Server1

{

            public static void main(String args[])

            {

            try

            {

                        DatagramSocket server=new DatagramSocket(1309);

                        while(true)

                        {

                                    byte[] sendbyte=new byte[1024];

                                    byte[] receivebyte=new byte[1024];

                                    DatagramPacket receiver=new DatagramPacket(receivebyte,receivebyte.length);

                                    server.receive(receiver);

                                    String str=new String(receiver.getData());

                                    System.out.println(str.trim());

                                    InetAddress addr=receiver.getAddress();

                                    int port=receiver.getPort();

                                    sendbyte=str.getBytes();

                                    DatagramPacket sender=new DatagramPacket(sendbyte,sendbyte.length,addr,port);

                                    server.send(sender);

                        }

            }

            catch(Exception e)

            {

                        System.out.println(e);

            }

            }

}

Output

E:\networks>javac Client1.java

E:\networks>javac Server1.java

E:\networks>java Client1

Enter the String:

hai

hai

E:\networks>java Server1

Hai