EchoClient.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class EchoClient {
    public final static int SERVER_PORT = 7;
    public final static String SERVER_IP = "127.0.0.1";
    public final static byte[] BUFFER = new byte[4096];
    public static void main(String[] args) {
        DatagramSocket ds = null;
        try {
            ds = new DatagramSocket();
            System.out.println("Client started ");
            InetAddress server = InetAddress.getByName(SERVER_IP);
            while(true) {
                System.out.println("Enter your messenger: ");
                InputStreamReader isr = new InputStreamReader(System.in);
                BufferedReader br = new BufferedReader(isr);
                String theString = br.readLine();
                byte[] data = theString.getBytes();

                DatagramPacket dp = new DatagramPacket(data, data.length, server, SERVER_PORT);
                ds.send(dp);

                DatagramPacket incoming = new DatagramPacket(BUFFER, BUFFER.length);
                ds.receive(incoming);
                System.out.println(new String(incoming.getData(), 0, incoming.getLength()));
            }
        } catch (IOException e) {
            System.err.println(e);
        } finally {
            if( ds != null) {
                ds.close();
            }
        }
    }
}