public void keyReleased(KeyEvent e) {
        int key = e.getKeyCode();
        switch (key) {
            case KeyEvent.VK_UP:
                action.thrust = 0;
                break;
            case KeyEvent.VK_LEFT:
                action.turn = 0;
                break;
            case KeyEvent.VK_RIGHT:
                action.turn = 0;
                break;
            case KeyEvent.VK_SPACE:
                action.shoot = false;
                break;
            case KeyEvent.VK_ALT:
                keyList.remove((Integer) KeyEvent.VK_ALT);
                break;
            case KeyEvent.VK_ENTER:
                keyList.remove((Integer) KeyEvent.VK_ENTER);
                break;
        }
    }