Swing的keyListener和同时按下的多个键

使用集合可记住当前按下的键,并检查每次按下键时是否按下多个键。

class MultiKeyPressListener implements KeyListener {

    // Set of currently pressed keys
    private final Set<Character> pressed = new HashSet<Character>();

    @Override
    public synchronized void keyPressed(KeyEvent e) {
        pressed.add(e.getKeyChar());
        if (pressed.size() > 1) {
            // More than one key is currently pressed.
            // Iterate over pressed to get the keys.
        }
    }

    @Override
    public synchronized void keyReleased(KeyEvent e) {
        pressed.remove(e.getKeyChar());
    }

    @Override
    public void keyTyped(KeyEvent e) {/* Not used */ }
}

KeyListener接口允许分别检测按键和释放。因此,您可以维护一组“活动键”,即已按下但尚未释放的键。