Servidor de Chat con Hilos

import java.util.ArrayList;
import java.net.ServerSocket;
import java.io.IOException;
import java.io.PrintStream;
import java.net.Socket;
 
public class Servidor {
        public static ArrayList<Socket> cliente = new ArrayList<Socket>();
        public static void main (String [] args) {
                ServerSocket servidor;
				try {
					servidor = new ServerSocket(4000);
					HiloEscuchaLlegadaCliente h = new HiloEscuchaLlegadaCliente(servidor);
	                h.start();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
        }
        public static void enviar(String m) {
                PrintStream p;
                for(Socket temp:cliente){
                        try {
							p = new PrintStream (temp.getOutputStream());
							p.println(m);
						} catch (IOException e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}
                }
        }
}

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
 
public class HiloEscuchaLlegadaCliente extends Thread {
        ServerSocket servidor;
        public HiloEscuchaLlegadaCliente (ServerSocket servidor) {
                this.servidor = servidor;
        }
        public void run(){
                Socket s;
                while(true){
                        try {
							s = servidor.accept();
							Servidor.cliente.add(s);
	                        HiloEscuchaCliente h = new HiloEscuchaCliente(s);
	                        h.start();
						} catch (IOException e) {
							// TODO Auto-generated catch block
							e.printStackTrace();
						}
                }
        }
}

import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;
 
public class HiloEscuchaCliente extends Thread {
        Socket s;
        public HiloEscuchaCliente(Socket s){
                this.s = s;
        }
        public void run () {
                Scanner a;
				try {
					a = new Scanner(s.getInputStream());
					while(true){
                        Servidor.enviar(a.nextLine());
					}
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
 
        }
}

import java.io.IOException;
import java.io.PrintStream;
import java.net.Socket;
import java.util.Scanner;
 
public class Cliente {
	public static void main(String [] args){
		try {
			Socket s = new Socket("127.0.0.1", 4000);
			HiloEscucha h = new HiloEscucha (s, "Cliente");
			h.start();
			Scanner a = new Scanner (System.in);
			PrintStream p;
 
			p = new PrintStream(s.getOutputStream());
			while(true){
				System.out.println("Yo: ");
				p.println(a.nextLine());
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;
 
 
public class HiloEscucha extends Thread {
	Socket s; // El que se crea al establecer la conexión
	String m; //Donde escucha el hilo
	public HiloEscucha (Socket s, String m) {
		this.m = m;
		this.s = s;
	}
	public void run (){
		Scanner a;
		try {
			a = new Scanner(s.getInputStream());
			while(true){
				System.out.println(m+"dice: "+a.nextLine());
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}