Question

I have a simple client-server program. In one thread GUI is running, when I click “connect” button on GUI, I connect to server in new thread, after some time I receive some data from server and I want to pass it to GUI – how can I do that?

Answer 1

Pass a reference to your GUI object to the reading thread, and have the reading thread invoke a method of the GUI instance when he has received the data.

If the GUI is a Swing GUI, you’ll need to wrap the call into SwingUtilities.invokeLater():

Thread readingThread = new MyReadingThread(gui);
readingThread.start();

and in the reading thread:

String data = readData();
SwingUtilities.invokeLater(new Runnable() {
    public void run() {
        gui.dataHasBeenReceived(data);
    }
});

Note that SwingWorker is designed specifically for this kind of use-case.