code

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.InputStream;
import java.net.*;
import java.nio.ByteBuffer;

public class Receive extends Thread{

    private int port;
    private String user_id;
    private boolean first=false;


    public Receive(int port, String name){
        this.port = port;
        this.user_id = name;
    }

    public void run(){
        try {
            int counter = 0;

            MulticastSocket ms = new MulticastSocket(port);
            InetAddress ia = InetAddress.getByName("224.2.2.2");
            ms.joinGroup(ia);

            BufferedImage image;

            while(true){

                DatagramPacket dp;
                byte[] buffer = new byte[10000];
                dp = new DatagramPacket(buffer, buffer.length);
                ms.receive(dp);
                ByteBuffer b = ByteBuffer.wrap(dp.getData());

                ByteArrayInputStream bi = new ByteArrayInputStream(buffer);
                image =  ImageIO.read(bi);
                String path = "C:\\Users\\shark\\IdeaProjects\\IE_HW1_Final\\src\\" + this.user_id.trim() + String.valueOf(counter) + ".jpg";
                ImageIO.write(image, "jpg", new File(path));
                System.out.println(user_id + "rcvd");

                synchronized (this){
                    counter ++;
                }
                Thread.sleep(1000);
            }

//            System.out.println("rcvd");
//            for (byte x:buffer) {
//                System.out.print(x);
//            }
        }catch (Exception e){
            System.out.println("client: " + e.getMessage());
        }
    }
}