UDP Server - Client

import java.io.*;
 import java.net.*;

class UDPClient
 {
    public static void main(String args[]) throws Exception
    {
       BufferedReader inFromUser =
          new BufferedReader(new InputStreamReader(System.in));
       DatagramSocket clientSocket = new DatagramSocket();
       InetAddress IPAddress = InetAddress.getByName("localhost");
       byte[] sendData = new byte[1024];
       byte[] receiveData = new byte[1024];
       String sentence = inFromUser.readLine();
       sendData = sentence.getBytes();
       DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress, 9876);
       clientSocket.send(sendPacket);
       DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
       clientSocket.receive(receivePacket);
       String modifiedSentence = new String(receivePacket.getData());
       System.out.println("FROM SERVER:" + modifiedSentence);
       clientSocket.close();
    }
 }


import java.io.*;
 import java.net.*;

class UDPServer
 {
    public static void main(String args[]) throws Exception
       {
          DatagramSocket serverSocket = new DatagramSocket(9876);
             byte[] receiveData = new byte[1024];
             byte[] sendData = new byte[1024];
             while(true)
                {
                   DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
                   serverSocket.receive(receivePacket);
                   String sentence = new String( receivePacket.getData());
                   System.out.println("RECEIVED: " + sentence);
                   InetAddress IPAddress = receivePacket.getAddress();
                   int port = receivePacket.getPort();
                   String capitalizedSentence = sentence.toUpperCase();
                   sendData = capitalizedSentence.getBytes();
                   DatagramPacket sendPacket =
                   new DatagramPacket(sendData, sendData.length, IPAddress, port);
                   serverSocket.send(sendPacket);
                }
       }
 }