Asynchronous JavaFX GUI with java.net Socket network

Question

I am attempting to write a server / client socket program and a client GUI using JavaFX. My issue that i am facing is where the GUI and socket connection doesn't run independently of each other meaning when i run my client program the GUI is shown and the socket connection doesn't occur. Then after closing the GUI window the socket connection will initialize as it should've originally. Also not greatly experienced with java in general and javafx/socket programming, just trying to learn.

import java.io.*;
import java.lang.*;
import java.net.Socket;

public class ClientSocket {

    public Socket socket;
    public BufferedReader bufferedReader;
    public BufferedWriter bufferedWriter;

    public ClientSocket(Socket socket) {

        try {
            this.socket = socket;
            this.bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            this.bufferedWriter = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
        } catch (IOException e) {
            closeConnection(socket, bufferedReader, bufferedWriter);
        }
    }
    public static void startConnection() {
        try {
            Socket socket = new Socket(Configuration.serverAddress, Configuration.serverPort);
            System.out.println("Client: Connected to server on " + Configuration.serverAddress +
                    " " + Configuration.serverPort + ".");
        } catch (IOException e) {
            System.out.println("Client: Error connecting to server on " + Configuration.serverAddress +
                    " " + Configuration.serverPort + ".");
        }
    }

    public static void closeConnection(Socket socket, BufferedReader bufferedReader, BufferedWriter bufferedWriter) {
        try {

            if (socket != null) {
                socket.close();
                System.out.println("Client: Socket connection has been closed to " + Configuration.serverAddress +
                        " " + Configuration.serverPort + ".");
            }
            if (bufferedReader != null) {
                bufferedReader.close();
            }
            if (bufferedWriter != null) {
                bufferedWriter.close();
            }
        }catch(IOException e){

        }
    }



}

import javafx.application.Application;
import javafx.stage.Stage;


public class ClientWindow extends Application{
    public void start(Stage gameWindow) {

        gameWindow.show();
    }

}

import javafx.application.Application;


public class Client {

    public static void main(String[] args) {
        Application.launch(ClientWindow.class, args);
        ClientSocket.startConnection();

    }


}

I have tried doing small steps, like getting the socket connection working properly by itself then trying to implement the javafx GUI alongside it. I still couldn't get it running the GUI and the socket connection together. I would assume the the JavaFX GUI is somehow on a loop that stops itself closing as soon as it starts which then holds the socket program from starting until the GUI has finished running. So only when the GUI is closed, then the socket program starts.

Answer 1

Why your socket doesn't connect until your application shuts down

Read the JavaFX Application javadoc to understand the lifecycle of a JavaFX application.

See especially the launch() method documentation:

The launch method does not return until the application has exited, either via a call to Platform.exit() or all of the application windows have been closed.

In this code, the socket connection won’t start until the JavaFX platform exits:

public static void main(String[] args) {
    Application.launch(ClientWindow.class, args);
    ClientSocket.startConnection();
}

How to fix it

To do something when an Application is initialized or started, implement your code in overridden init() or start() methods. Similarly, stop() is for releasing resources, for example shutting down other threads or persistent connections that your application may have opened.

Related example and resources

• Example of a JavaFX application which uses socket connections

The example uses sockets from a JavaFX application. It demonstrates both synchronous and asynchronous modes of operation.

The asynchronous operation mode is more challenging to program. Asynchronous calls might only be required if your application has long-running blocking calls on socket streams.

If you use an asynchronous calling mode, then I recommend studying:

• Concurrency in Java
• Concurrency in JavaFX

JavaFX concurrency questions and answers on StackOverflow may also assist you.