等待计时器/进程完成，然后再继续

Question

I have a function that flashes the border of a JButton which gets called multiple times in a row. I want the processes to continue only after the entirety of the function completes. Right now, the flashing starts for one button, then it will start for another before the flashing stopped for the first button. The function looks like the following which is in a class that extends JButton:

    public void flash() {
    final Timer timer = new Timer(7, new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            alpha += increment;
            if (alpha >= 255) {
                alpha = 255;
                increment = -increment;
            }
            if (alpha <= 0) {
                alpha = 0;
                increment = -increment;
            }
            setBorder(BorderFactory.createLineBorder(new Color(81, 171, 112, alpha), 4));
        }
    });

    timer.start();

    final Timer delay = new Timer(
            2000,
            new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            setBorder(BorderFactory.createLineBorder(new Color(0, 0, 0, 0), 0));
            timer.stop();
        }
    });
    delay.setRepeats(false);
    delay.setCoalesce(true);
    delay.start();
}

Answer 1

A fundamental problem you have here is that there are multiple button objects. That means each flash() lives in an independent object (since it isn't static). That means each button has no idea if the others are flashing or not.

What you need is one place that does the flashing. A place where whatever needs the flashing to happen can dump the work. A place that knows about the buttons so it can manipulate their borders. Lets call it the flasherQueue .

A static member could be used for this but a more flexible design would inject the single flasherQueue object into each of your button objects as they are constructed. Each button knowing about flasherQueue is only required if it's the buttons that decide when to flash.

At this point you are free to make your buttons flash() method into a blocking call. Whatever you have decide to flash a button simply passes a reference to the button to the flasherQueue . The flasherQueue , looping in it's own thread, grinds through any buttons it's been given in order, waiting for each to finish flashing.

Done this way you should only ever have at most one flashing button at a time and should be free to process other events so your GUI should repaint.

This is really a degenerative form of producer / consumer . As long as you have only one consumer calling a buttons flash() only one button will flash at a time. You'll probably be able to make use of java's BlockingQueue for your data structure behind flasherQueue .