CODEWITHSUNDEEP
javamultithreadingswingeventsthread-safety
Quillion
Quillion

Reputation: 6476

Java swing UI Threads and event button events

So as far as I understood, all the swing components should be created, modified and queried only from the EDT.
So if I happen to press a JButton "submit" let's say, that will pack up all the information from the text boxes, send that data to controller and then controller will send it to other controllers which will eventually send stuff to the server. What thread is the action for that button is running on? If it is running on EDT, how do I exit it to send the data to controller from the main thread? Should I even use main thread to send data to server from the controller?

So what I am saying is this

java.awt.EventQueue.invokeLater(new Runnable()
{
    @Override
    public void run()
    {
        JButton button = new JButton("Submit");
        button.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent e)
            {
                // WHAT THREAD DO ACTIONS HERE RUN ON?
                // AND HOW DO I MAKE THEM RUN ON MAIN THREAD?
                // AND WHAT THREAD SHOULD I RUN THING ON HERE?
            }
        });
    }
});

Upvotes: 1

Views: 615

Answers (1)

Harald K
Harald K

Reputation: 27074

Any action triggered from Swing will run on the EDT. So the code in your actionPerformed method will already be executed on the EDT, without any special handling by you.

To start a long-running task, like sending data to a server, use a SwingWorker or a Callable and an ExecutorService.

I prefer using a SwingWorker when implementing a Swing UI, as has it a useful API for publishing updates and makes the callbacks when the task is done automatically happen on the EDT.

Upvotes: 4

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