Server-GUI freezes when waiting for connections

Question

I'm trying to create a multithreaded server, connecting to it through a client works fine, but the GUI is frozen. Probably since it is constantly listening for incoming connections it is stuck in a while loop. So, do i need to create a thread for the multithreaded server (which itself will be creating threads) or how would i go about fixing this?

MultiThreadedServer:

public class MultiThreadServer{

    public static final int PORT = 2000;
    //function below is called by the GUI. 
    public void startServer() throws IOException {
        ServerSocket s = new ServerSocket(PORT);
        System.out.println("Server socket: " + s);
        System.out.println("Server listening...");
        try { while(true) {
            // Blocks until a connection occurs:
            Socket socket = s.accept();
            System.out.println("Connection accepted.");
            System.out.println("The new socket: " + socket);
            try {
                ClientThread t = new ClientThread(socket);
                System.out.println("New thread started.");
                System.out.println("The new thread: " + t);

                }
                catch(IOException e) {
                    System.out.println("===Socket Closed===");
                    socket.close();
                }
            } 
        } 
        finally { System.out.println("===ServerSocket Closed==="); s.close(); }
        } 
    } 
}

ServerGUI:

public class ServerGUI extends Application implements Initializable{

    @FXML private MenuItem startConn;

    @Override
    public void start(Stage stage) throws Exception {
        try {
            Parent root = FXMLLoader.load(getClass().getResource("ServerGUI.fxml"));
            stage.setScene(new Scene(root));
            stage.show();
        } catch (IOException ex) {
            ex.printStackTrace();
            System.exit(0);
        }
    }
    public static void main(String[] args) {
        launch(args);
    }
    @Override
    public void initialize(URL location, ResourceBundle resources) {

        startConn.setOnAction(e -> {
            try {
                MultiThreadServer mts = new MultiThreadServer();
                mts.startServer();
                System.out.println("Starting Server...");
            } catch (IOException e1) {
                e1.printStackTrace();
            }
        });
    }
}

*So, do i need to create a thread for the multithreaded server* - Yes. The server class invokes `accept()`, which is a blocking method: it will freeze your app if you don't invoke it in a separate thread. — BackSlash, Dec 08 '17 at 16:54
Move `s.accept` and while loop into `ClientThread` run method. — tsolakp, Dec 08 '17 at 16:56
@Joel https://stackoverflow.com/questions/17758411/java-creating-a-new-thread — BackSlash, Dec 08 '17 at 16:58

score 0 · Accepted Answer · answered Dec 08 '17 at 17:08

As i suspected, a new thread for the server was required.

MultiThreadServer:

public Runnable startServer() throws IOException {

After making the function Runnable i added this:

ServerGUI:

startConn.setOnAction(e -> {
            Thread t1 = new Thread(new Runnable() {
                public void run()
                {
                    MultiThreadServer mts = new MultiThreadServer();

                    try {
                        mts.startServer();
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }});  
                t1.start();

Thanks to user BackSlash for providing reference-link.

Server-GUI freezes when waiting for connections

1 Answers1