GUI not updating visually before running ActionEve

Question

To expound a little more, I have a GUI that looks like:

Then I have an action listener on the OK button that starts like:

//OK Button Action Listener
private void okButtonActionPerformed(ActionEvent e) {   
    //Enable/Disable Buttons
    okButton.setEnabled(false);
    cancelButton.setEnabled(true);
    updateCheckbox.setEnabled(false);
    //Move on to a series of other methods here...

Which should, in theory, make this happen:

However, instead, I get the following until ALL methods and other things connected to the OK button are completed:

This obviously can't happen, because the idea is to make the cancel button available and the OK button and several other tick-boxes unavailable for the duration of the program (Image 2), where, instead, it freezes in a half-state (Image 3). Is there any way to combat this?

Answer 1

Yup, that's because you have blocked with EDT with your other methods.

You need to use another Thread to do the work in the background otherwise the GUI will be blocked.

In Swing applications it is recommended that any long running tasks are carried out on a SwingWorker.

Take a look at the documentation for an introduction.

A SwingWorker will carry out a task that it is given and it can report back to the GUI when it is done. This will be done in a non-blocking way so that you can still use the GUI while the task it being carried out.

If you want to be able to cancel the background task you need to keep a reference to the SwingWorker so that you can call the cancel method. In this case the work method needs to be interruptable, otherwise the task cannot be cancelled.

Answer 2

Every time you execute logic from the GUI you should be using the SwingWorker in the following way:

SwingWorker myWorker= new SwingWorker<String, Void>() {
    @Override
    protected String doInBackground() throws Exception {
        //Execute your logic
        return null;
    }
};
myWorker.execute();

If you want to update the GUI from inside this logic use InvokeLater:

SwingUtilities.invokeLater(new Runnable() {
    @Override
    public void run() {
        //To update your GUI
    }
});

With this you can be sure that both your logic and your GUI stay responsive.

Edit:

You could also use invokeAndWait if this suits your needs more. Link to related answer

Answer 3

//Move on to a series of other methods here...

Make sure you don't block the GUI thread (EDT) with long-running operations. Instead use SwingWorker.

Answer 4

Are you doing some processing on the same thread that's handling the GUI? You might want to look into a SwingWorker thread to do the heavy stuffin the background so your UI remains responsive if so.