What's the difference between the 2 ways of showing window in Swing?

Question

I am new to Java Swing GUI development. In some sample code, I see Swing window is shown with the EventQueue.invokeLater():

public static void main(String[] args) {
    EventQueue.invokeLater(new Runnable() {
        @Override
        public void run() {
            // TODO Auto-generated method stub
            MainWindow window=new MainWindow();
            window.setDefaultCloseOperation(EXIT_ON_CLOSE);
            window.setVisible(true);                
        }
    });

    System.out.println("main exited");

}

But as I tried, I can also show a window without using EventQueue.invokeLater():

public static void main(String[] args) {

    MainWindow window=new MainWindow();
    window.setDefaultCloseOperation(EXIT_ON_CLOSE);
    window.setVisible(true);    

    System.out.println("main exited");

}

So what's the difference? When should I use each method?

and http://stackoverflow.com/questions/6567870/what-does-swingutilities-invokelater-do — testinfected, Mar 28 '15 at 01:51

score 4 · Accepted Answer · answered Mar 28 '15 at 01:48

4

When invoking code from the main() method you should ALWAYS use the EventQueue.invokeLater() because all Swing components should be created on the Event Dispatch Thread (EDT).

Yes, the code will work 99.99% of the time when creating a simple GUI the other way, but you don't want to waste time debugging a random bug when it doesn't work.

Read the section from the Swing tutorial on Concurrency and Swing for more information about the EDT and why Swing components should be created on the EDT.

Note, code executed from a Swing listener is invoked from the EDT.

answered Mar 28 '15 at 01:48

camickr

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1

Like most, if not all, GUI frameworks you should always run the GUI on their EDT, or equivalent. – dazito Mar 28 '15 at 01:50
@dwnz Indeed. I used to coding for WinForm, and there's similar idea. – smwikipedia Mar 28 '15 at 02:52

What's the difference between the 2 ways of showing window in Swing?

1 Answers1