Java Server/Client Applicaton - problem with sending data back

Question

Hello!
I'm trying to write a small server/client chat application in Java. It's server with availability to accept connections from many clients and it's app just for fun... However, I've come up against a huge problem: everything what clients send, arrives to server (I'm sure about that because it is displayed on the Server Application screen) and then server should send it back to all clients but it doesn't work. I have no faintest idea what causes this problem. Maybe you can help me?
Here is my server app code:
import java.net.*;
import java.util.*;
import java.io.*;
* @author Robin
public class Server {
    ServerSocket serw = null;
    Socket socket = null;
    String line = null;
    Vector<ClientThread> Watki = new Vector();
    ClientThread watek = null;
    public Server(int port) {
        try {
            serw = new ServerSocket(port);           
            line = "";
            while(true) {
                System.out.println("Running. Waiting for client to connect...");
                socket = serw.accept();
                System.out.println("Connected with:\n" + socket.getInetAddress() + "\n");
                watek = new ClientThread(socket);
                Watki.addElement(watek);
                Watki.firstElement().Send("doszlo?");
        }catch (IOException e) {
            System.out.println("BLAD: " + e);
    public void sendToAll(String s) {
        for(int i = 0; i < Watki.size(); i++) {
            Watki.elementAt(i).Send(s);
    public class ClientThread extends Thread {
        Socket socket;
        DataInputStream in = null;
        DataOutputStream out = null;
        String line = null;
        public ClientThread(Socket s) {
            try {
                this.socket = s;
                in = new DataInputStream(s.getInputStream());
                out = new DataOutputStream(s.getOutputStream());
                start();
            }catch (IOException e) {
                System.out.println("BLAD: " + e);
        public void Send(String s) {
            try {
                out.writeUTF(s);
            }catch (IOException e) {
                System.out.println("BLAD: " + e);
        public void run() {
            try {
                line = "";
                while (true) {
                    line = in.readUTF();
                    System.out.println(line);
                    sendToAll(line);
            }catch (IOException e) {
                System.out.println("BLAD: " + e);
    public static void main(String[] args) {
        Server serwer = new Server(5000);
}And here is client app code:
import java.net.*;
import java.util.*;
import java.io.*;
* @author Robin
public class Client implements Runnable {
    Socket socket = null;
    BufferedReader keyIn = new BufferedReader(new InputStreamReader(System.in));
    DataInputStream in = null;
    DataOutputStream out = null;
    String line = null;
    public Client(String host, int port) {
        try {
            System.out.println("Connecting to " + host + ":" + port);
            socket = new Socket(host, port);
            System.out.println("Connected\nTALK:");
            out = new DataOutputStream(socket.getOutputStream());
            in = new DataInputStream(socket.getInputStream());
            line = "";
            while(!line.toLowerCase().equals(".bye")) {
                line = keyIn.readLine();
                Send(line);
        }catch (UnknownHostException e) {
            System.out.println("BLAD: " + e);
        }catch (IOException e) {
            System.out.println("BLAD: " + e);
    public void Send(String s) {
        try {
            out.writeUTF(s);
        }catch (IOException e) {
            System.out.println("BLAD: " + e);
    public void run() {
        String loaded = "";
        try {
            while(true) {
                loaded = in.readUTF();
                System.out.println(loaded);
        }catch (IOException e) {
            System.out.println("BLAD: " + e);
    public static void main(String[] args) {
        Client client = new Client("localhost", 5000);
}By the way, this app is mainly written in English language (text that appears on the screen) however in functions I used Polish language (for example: BLAD - it means ERROR in English). Sorry for that :)

Answer 1

Yeap, I will change those exceptions later, thanks for advice.
You asked what's going on with it: both applications start with no errors, but when I write something in client side it should be sent to the server and then forwarded to all connected clients but it stops somewhere. However, I added a one line to the server code
line = in.readUTF();
System.out.println(line);
sendToAll(line); and after it reads message from client (no matter which one) it shows that message on the server side screen, then it should send this message to all clients but it doesn't work in this moment. What's confusing: no errors occurs, so it's rather a mistake in my code, but where?
Edited by: Robin3D on Sep 30, 2009 9:07 AM