MAIN.JAVA

package org.suai;

import java.net.DatagramSocket;
import java.net.InetAddress;

public class Main {

    public static void main(String[] args) throws Exception{
        DatagramSocket clientSocket = new DatagramSocket(9876);
        InetAddress IPAddress = InetAddress.getByName("localhost");
        Thread ww = new Thread(new WorkerWriter(clientSocket, IPAddress, 9877));
        Thread wr = new Thread(new WorkerReader(clientSocket));
        ww.start();
        wr.start();
    }
}











WORKERREADER.JAVA

package org.suai;

import java.net.DatagramPacket;
import java.net.DatagramSocket;

public class WorkerReader implements Runnable{

    private DatagramSocket serverSocket;
    private byte[] receiveData = new byte[1024];

    public WorkerReader(DatagramSocket ss){
        serverSocket = ss;
    }

    public void run(){
        DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
        int i = 0;
        while (true) {
            try {
                serverSocket.receive(receivePacket);
                String sentence = new String(receivePacket.getData());
                System.out.println(sentence);
                while (receiveData[i] != 0)
                    receiveData[i++] = 0;
                i = 0;
            }
            catch (Exception e){
                e.printStackTrace();
            }
        }
    }
}











WORKERWRITER.JAVA

package org.suai;

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

import static java.lang.System.exit;

public class WorkerWriter implements Runnable {

    private BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));
    private DatagramSocket serverSocket;
    private InetAddress IPAddress;
    private int port;
    private String str;
    private String name = "Client";
    private String quit = "@quit";
    private byte[] sendData = new byte[1024];

    public WorkerWriter(DatagramSocket ss, InetAddress ia, int p){
        serverSocket = ss;
        IPAddress = ia;
        port = p;
    }

    public void run(){
        while (true) {
            try {
                str = inFromUser.readLine();
                if (str.equals(quit)){
                    exit(0);
                }
                if (str.startsWith("@name")){
                    name = str.substring(6);
                    continue;
                }
                str = name + ": " + str;
                sendData = str.getBytes();
                DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, IPAddress,
                        port);
                serverSocket.send(sendPacket);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}