在JOptionPane中更新消息 [英] Updating message in JOptionPane

问题描述

我正在尝试制作一个在JOptionPane中显示时间的数字时钟.我设法在消息对话框上显示时间.但是，我不知道如何使它在对话框中每秒更新一次时间.

I am trying to make a digital clock which displays the time in a JOptionPane. I've managed to display the time on the message dialog box. However, I can't figure out how to make it update the time at every second in the dialog box.

这是我目前拥有的:

    Date now = Calendar.getInstance().getTime();
    DateFormat time = new SimpleDateFormat("hh:mm:ss a.");

    String s = time.format(now);

    JLabel label = new JLabel(s, JLabel.CENTER);
    label.setFont(new Font("DigifaceWide Regular", Font.PLAIN, 20));

    Toolkit.getDefaultToolkit().beep();

    int choice = JOptionPane.showConfirmDialog(null, label, "Alarm Clock", JOptionPane.YES_NO_OPTION, JOptionPane.PLAIN_MESSAGE);

推荐答案

这很可怕，我认为应该更容易...

That was scary, it worked easier that I thought it should...

基本上，您需要某种"ticker"，可用于更新标签的文本...

Basically, you need some kind of "ticker" that you can use to update the text of the label...

public class OptionClock {

    public static void main(String[] args) {
        new OptionClock();
    }

    public OptionClock() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                Date now = Calendar.getInstance().getTime();
                final DateFormat time = new SimpleDateFormat("hh:mm:ss a.");

                String s = time.format(now);

                final JLabel label = new JLabel(s, JLabel.CENTER);
                label.setFont(new Font("DigifaceWide Regular", Font.PLAIN, 20));

                Timer t = new Timer(500, new ActionListener() {
                    @Override
                    public void actionPerformed(ActionEvent e) {
                        Date now = Calendar.getInstance().getTime();
                        label.setText(time.format(now));
                    }
                });
                t.setRepeats(true);
                t.start();

                int choice = JOptionPane.showConfirmDialog(null, label, "Alarm Clock", JOptionPane.YES_NO_OPTION, JOptionPane.PLAIN_MESSAGE);

                t.stop();
            }
        });
    }
}

因为我们不想违反Swing的单线程规则，所以最简单的解决方案是使用每500毫秒左右跳动一次的javax.swing.Timer(捕获边缘情况).

Because we don't want to violate the single thread rules of Swing, the simplest solution would be to use a javax.swing.Timer that ticks every 500 milliseconds or so (catch edge cases).

通过虚拟设置标签的文本，它会自动发布重绘请求，这使我们的生活变得简单...

By virtual of setting the label's text, it automatically posts a repaint request, which makes our life simple...

这篇关于在JOptionPane中更新消息的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！