Java - 等待空间或在一定时间后返回

Question

我的 Java 程序中有一个函数等待用户按下空格键。我想对此进行修改，以便在经过一定时间后仍未按下空格时该函数也将返回。

我想保持这个功能不变，不改变风格，所以我非常感谢修改这个功能的答案。谢谢!

public void waitForSpace() {
        final CountDownLatch latch = new CountDownLatch(1);
        KeyEventDispatcher dispatcher = new KeyEventDispatcher() {
            public boolean dispatchKeyEvent(KeyEvent e) {
                if (e.getID() == KeyEvent.KEY_PRESSED && e.getKeyCode() == KeyEvent.VK_SPACE) {
                    latch.countDown();
                }
                return false;
            }
        };
        KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(dispatcher);
        try {
            //current thread waits here until countDown() is called (see a few lines above)
            latch.await();
        } catch (InterruptedException e1) {
            e1.printStackTrace();
        }  
        KeyboardFocusManager.getCurrentKeyboardFocusManager().removeKeyEventDispatcher(dispatcher);
    }

Answer 1

尝试使用 CountDownLatch#await(long, TimeUnit)相反……

public void waitForSpace() {
    final CountDownLatch latch = new CountDownLatch(1);
    KeyEventDispatcher dispatcher = new KeyEventDispatcher() {
        public boolean dispatchKeyEvent(KeyEvent e) {
            if (e.getID() == KeyEvent.KEY_PRESSED && e.getKeyCode() == KeyEvent.VK_SPACE) {
                latch.countDown();
            }
            return false;
        }
    };
    KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(dispatcher);
    try {
        //current thread waits here until countDown() is called (see a few lines above)
        latch.await(30, TimeUnit.SECONDS);
    } catch (InterruptedException e1) {
        e1.printStackTrace();
    }  
    KeyboardFocusManager.getCurrentKeyboardFocusManager().removeKeyEventDispatcher(dispatcher);
}