import java.net.*;
import java.io.*;
import java.util.*;

public class Server extends Thread{
    private ServerSocket server = null;
    private LinkedList<ServerThread> clients = new LinkedList<ServerThread>();

    public Server(int port) throws IOException {
        server = new ServerSocket(port);
    }

    public void run(){
        while(true){
            try{
                addThread(server.accept());
            } catch (IOException e){
                e.printStackTrace();
            }
        }
    }

    private void addThread(Socket socket) throws IOException {
        ServerThread serverThread = new ServerThread(this, socket);
        clients.add(serverThread);
        clients.getLast().start();
    }

    public synchronized void handle(String input) throws IOException {
        for(ServerThread ss : clients){
            ss.send(input);    
        }
    }   

    public static void main(String[] args){
        try{
            Server myServer = new Server(8080);
            myServer.start();
        } catch (IOException e){
            e.printStackTrace();
        }
    }
}


import java.net.*;
import java.io.*;

public class ServerThread extends Thread{
    private Server server = null;
    private Socket socket = null;
    private DataInputStream in = null;
    private DataOutputStream out = null;

    public ServerThread(Server server, Socket socket) throws IOException {
        this.server = server;
        this.socket = socket;
        in = new DataInputStream(new BufferedInputStream(socket.getInputStream()));
        out = new DataOutputStream(new BufferedOutputStream(socket.getOutputStream()));
    }

    public void run(){
        while(true){
            try {
                server.handle(in.readUTF());
            } catch (IOException e){
                e.printStackTrace();
            }
        } 
    }

    public void send(String message) throws IOException {
        out.writeUTF(message);
        out.flush();    
    }

}


import java.net.*;
import java.io.*;

public class Client extends Thread{
    private Socket socket = null;
    private DataInputStream in = null;
    private DataOutputStream out = null;
    private ClientThread client = null;

    public Client(String serverAddress, int serverPort) throws UnknownHostException, IOException {
        socket = new Socket(serverAddress, serverPort);
        in = new DataInputStream(System.in);
        out = new DataOutputStream(socket.getOutputStream());
        client = new ClientThread(this, socket);
    }

    public void run(){
        while(true){
            try{
                out.writeUTF(in.readLine());
                out.flush();
            } catch (IOException e){
                e.printStackTrace();
            }
        }
    }

    public void handle(String message){
        System.out.println(message);
    }

    public static void main(String[] args) {
        try{
            Client myClient = new Client("ernie.icslab.agh.edu.pl", 8080);
            myClient.start();
        } catch (UnknownHostException e){
            e.printStackTrace();
        } catch (IOException e){
            e.printStackTrace();
        }
    }
}


import java.net.*;
import java.io.*;

public class ClientThread extends Thread{
    private Socket socket = null;
    private Client client = null;
    private DataInputStream in = null;

    public ClientThread(Client client, Socket socket) throws IOException {
        this.client = client;
        this.socket = socket;
        in = new DataInputStream(socket.getInputStream());
        start();
    }

    public void run(){
        while(true){
            try{
                client.handle(in.readUTF());
            } catch (IOException e){
                e.printStackTrace();
            }
        }
    }
}