ActionEvent 后的 Infinite-while 或 for 循环无法正常工作。为什么？

Question

public void myMethod()
{
if (capture.isOpened()) {
    while (true) { //This is The main issue.
        capture.read(webcam_image);
        if (!webcam_image.empty()) {
            webcam_image = my_panel.detect(webcam_image);
            temp = my_panel.matToBufferedImage(webcam_image);
            my_panel.setimage(temp);
            my_panel.repaint();
            System.out.print("."); // It should prints "." but the above code doesn't works.
        } else {
            System.out.println(" --(!) No captured frame -- Break!");
            break;
        }
    }
}
}

这是调用上述方法的代码... 实际上它是一个可以在单击菜单时触发的 ActionEvent。

if (e.getActionCommand().equals("goLive")) {
        System.out.println("Live...");
        myMethod();
}

实际上我知道这是无限 while 循环的问题，但在这里我需要不惜一切代价设置这个条件。

Answer 1

此类问题的确切解决方案是 Timer 类。我们可以使用下面的代码来解决这个问题。

Timer timer = new Timer();
    timer.schedule(new TimerTask() {
        @Override
        public void run() {
            myMethod();
        }
}, 0);

感谢谷歌，oracle 和 java doc

Answer 2

假设 myMethod 被事件侦听器 (actionPerformed) 调用，则无限循环正在阻塞 event dispatch thread。 您可以通过使用SwingWorker 或在另一个线程上执行循环来避免这种情况：

public void myMethod()
{
if (capture.isOpened()) {
    new Thread(new Runnable() { //Create a new thread and pass a Runnable with your while loop to it
        @Override public void run() {
            while (true) {
                capture.read(webcam_image);
                if (!webcam_image.empty()) {
                    webcam_image = my_panel.detect(webcam_image);
                    temp = my_panel.matToBufferedImage(webcam_image);
                    SwingUtilities.invokeLater(new Runnable() { //The following lines affect the GUI and must be executed on the event dispatch thread, so they should be wrapped inside a Runnable
                        @Override public void run() {
                            my_panel.setimage(temp);
                            my_panel.repaint();
                        }
                    }
                    try{
                        Thread.sleep(xxx); //consider waiting for a moment (e.g. 16ms)
                    } catch(InterruptedException e) { ... }
                    System.out.print(".");
                } else {
                    System.out.println(" --(!) No captured frame -- Break!");
                    break;
                }
            }
        }
    }).start(); //Let the thread loop in the background
}
}