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Thread: Why should Swing GUI code be placed on the EDT?

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    Default Why should Swing GUI code be placed on the EDT?

    According to what I read, “when programming in Swing, your GUI creation code should be placed on the Event Dispatch Thread (EDT). This will prevent potential race conditions that could lead to deadlock.” (See below for code.)

    Why is this? How could making a GUI lead to deadlock?

        public static void main(String[] args) {
            SwingUtilities.invokeLater(new Runnable() {
                public void run() {
                    createAndShowGUI();
                }
            });
        }


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    Default Re: Why should Swing GUI code be placed on the EDT?

    Also posted here and here.

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    Default Re: Why should Swing GUI code be placed on the EDT?

    As I wrote in the other topic: are these forums somehow connected and, if so, is there a preferred place?

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    Default Re: Why should Swing GUI code be placed on the EDT?

    If you don't understand my answer, don't ignore it, ask a question.

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    Default Re: Why should Swing GUI code be placed on the EDT?

    Believe me, things get weird if you dont put all your Swing code on the EDT. Certain components might disappear, or perhaps they get rendered at the wrong location, sometimes the entire Swing application will become just a white color plane.
    Why? Because swing was designed to be used on the EDT and if you dont invoke all Swing methods on the EDT you do it wrong. Just believe me, bad things WILL happen sooner or later.

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    Default Re: Why should Swing GUI code be placed on the EDT?

    Do I also need to use the above code (explicitly put the Swing code on the EDT) if my entire program runs in one threat, i.e. my program never explicitly creates any threats?
    Last edited by evert67; October 3rd, 2014 at 09:14 AM.

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    Default Re: Why should Swing GUI code be placed on the EDT?

    There are several good articles on the 'net on this topic. Search 'java swing edt', 'java swing thread safe', 'java swing multi-threading', etc.

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    Default Re: Why should Swing GUI code be placed on the EDT?

    If you run your entire program on the EDT then every swing action will obviously run on the EDT as well and you are good.
    However, any heavy computations should NOT be run on the EDT or the application migth become unresponsive. If you need to access any databases, files, have any networking code, or just in general do any heavy work, put it into a worker thread.

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