Can it be done in a more elegant way with the Swing Timer?

问题

Bellow is the code for the simplest GUI countdown. Can the same be done in a shorter and more elegant way with the usage of the Swing timer?

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;

public class CountdownNew {

    static JLabel label;

    // Method which defines the appearance of the window.   
    public static void showGUI() {
        JFrame frame = new JFrame("Simple Countdown");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        label = new JLabel("Some Text");
        frame.add(label);
        frame.pack();
        frame.setVisible(true);
    }

    // Define a new thread in which the countdown is counting down.
    public static Thread counter = new Thread() {

        public void run() {
            for (int i=10; i>0; i=i-1) {
                updateGUI(i,label);
                try {Thread.sleep(1000);} catch(InterruptedException e) {};
            }
        }
    };

    // A method which updates GUI (sets a new value of JLabel).
    private static void updateGUI(final int i, final JLabel label) {
        SwingUtilities.invokeLater( 
            new Runnable() {
                public void run() {
                    label.setText("You have " + i + " seconds.");
                }
            }
        );
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                showGUI();
                counter.start();
            }
        });
    }

}

回答1:

Yes you SHOULD use a Swing Timer. You SHOULD NOT, use a util Timer and TimerTask.

When a Swing Timer fires the code is executed on the EDT which means you just need to invoke the label.setText() method.

When using the uitl Timer and TimerTask, the code DOES NOT execute on the EDT, which means you need to wrap your code in a SwingUtilities.invokeLater to make sure the code executes on the EDT.

And that is way using a Swing Timer is shorter and more elegant than your current approach, it simplifies the coding because to code is executed on the EDT.

回答2:

You could make it a little more elegant by using Timer with an appropriate TimerTask.

回答3:

Yes, use a timer. updateGUI would be the code for the timer task, but it will need some changes as you won't be able to pass in i for each call since you just get a run() method.

来源：https://stackoverflow.com/questions/2487349/can-it-be-done-in-a-more-elegant-way-with-the-swing-timer

标签

java

user-interface

swing

timer