CODEWITHSUNDEEP
javaswingkeylistener
Julius Eckert
Julius Eckert

Reputation: 1511

Java Swing - Pressed key gets not released (sometimes)

For a game, I use a KeyListener to know when a key is pressed down.

public synchronized void keyPressed(KeyEvent e) {
    if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
        keyRightIsDown = true;
    }
}

public synchronized void keyReleased(KeyEvent e) {
    if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
        keyRightIsDown = false;
    }
}

This works 99.9%. But from time to time (often enough), the keyReleased is not called, when the key is released (causing the game character to continue moving right - pressing the key again fixes the problem).

[Maybe relevant:] I use OSX 10.6 and I press down multiple keys at the same time quiet often.

How can I make this work 100% ?

Upvotes: 1

Views: 1087

Answers (2)

dilbert
dilbert

Reputation: 127

similar questions were asked several times, take a look at

how-to-know-when-a-user-has-really-released-a-key-in-java

or

how-to-stop-repeated-keypressed-keyreleased-events-in-swing

i hope this helps;

edit:

what you could do, is using a polling mechanism:

static Toolkit kit = Toolkit.getDefaultToolkit();
..
if (kit.getLockingKeyState(KeyEvent.VK_X))
..

this means you always check in your thread if a certain key is pressed. But keep in mind that polling is not efficient.

Upvotes: 1

mKorbel
mKorbel

Reputation: 109815

may be would be better look at KeyBindings, that's easily to build Listener for key actions as KeyListener

Upvotes: 1

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