단체 채팅 구현

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.LinkedList;
import java.util.List;

public class Server {
	static List<DataOutputStream> outs;

	public static void main(String[] args) {
		try {
			ServerSocket serverSocket = new ServerSocket(2400);
			outs = new LinkedList();
			Socket socket;
			DataOutputStream out;
			while (true) {
				socket = serverSocket.accept();
				new Broadcaster(new DataInputStream(socket.getInputStream()),
						out = new DataOutputStream(socket.getOutputStream())).start();
				outs.add(out);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}

	}
	static class Broadcaster extends Thread {
		DataInputStream in;
		DataOutputStream out;
		Broadcaster(DataInputStream in, DataOutputStream out) {
			this.in = in;
			this.out = out;
		}
		@Override
		public void run() {
			while (true) {
				try {
					String message = in.readUTF();
					for (DataOutputStream out : outs) {
						if (out != this.out) {
							out.writeUTF(message);
						}
					}
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
	}
}

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;

public class Client {

	public static void main(String[] args) {
		try {
			Socket socket = new Socket("localhost", 2400);
			new Sender(socket).start();
			new Receiver(socket).start();
		} catch (Exception e) {
			e.printStackTrace();
		}

	}
}
class Sender extends Thread {
	Scanner sc;
	DataOutputStream out;

	Sender(Socket socket) {
		try {
			this.out = new DataOutputStream(socket.getOutputStream());
		} catch (IOException e) {
			e.printStackTrace();
		}
		this.sc = new Scanner(System.in);
	}

	@Override
	public void run() {
		while (true) {
			try {
				this.out.writeUTF(sc.nextLine());
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
}
class Receiver extends Thread {
	DataInputStream in;

	Receiver(Socket socket) {
		try {
			this.in = new DataInputStream(socket.getInputStream());
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	@Override
	public void run() {
		while (true) {
			try {
				System.out.println(this.in.readUTF());
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
}