Do Robot methods need to be run on the event queue?

Question

Robot is part of the AWT library, but it seems quite different from most all the rest of the library. I am creating a Swing GUI that mixes Swing with Java Native Access (JNA

Answer 1

The Robot methods you mentioned should not be run on the EDT. Taking a look at the source code revealed that each one of these "event" methods has one thing in common (the afterEvent call):

public synchronized void keyPress(int keycode) {
    checkKeycodeArgument(keycode);
    peer.keyPress(keycode);
    afterEvent();
}

public synchronized void mousePress(int buttons) {
    checkButtonsArgument(buttons);
    peer.mousePress(buttons);
    afterEvent();
}

// etc

private void afterEvent() {
    autoWaitForIdle();
    autoDelay();
}

private void autoWaitForIdle() {
    if (isAutoWaitForIdle) {
        waitForIdle();
    }
}

public synchronized void waitForIdle() {
    checkNotDispatchThread();
    /* snip */
}

private void checkNotDispatchThread() {
    if (EventQueue.isDispatchThread()) {
        throw new IllegalThreadStateException("Cannot call method from the event dispatcher thread");
    }
}

If you call any of these methods on the EDT while Robot.isAutoWaitForIdle is true, an exception will be thrown. This stands to reason that even if isAutoWaitForIdle is false, these methods shouldn't be called from the EDT.