Question

这应该显示时间，但是当我运行代码时，我得到代码执行的时间。如何让它每秒显示当前时间？

    private void Timer(java.awt.event.WindowEvent evt) {                       
        DateFormat timeFormat = new SimpleDateFormat ("HH:mm:ss");
        Calendar cali = Calendar.getInstance();
        cali.getTime();
        String time = timeFormat.format(cali.getTimeInMillis()) ;
        System.out.println( timeFormat.format(cali.getTimeInMillis()) );
        jLabel4.setText(time);
    }

Answer 1

而不是使用线程并不断使用invokeLater返回到Swing线程，这是少数几个Swing Timer是个好主意的情况之一。

Swing Timer已经回调事件调度线程，因此您可以直接从回调中更新标签。

http://docs.oracle.com/javase/tutorial/uiswing/misc/timer.html

Answer 2

参考Ankur的代码

Timer timer = new Timer("Display Timer");

TimerTask task = new TimerTask() {
    @Override
    public void run() {
        // Task to be executed every second
        try {
            SwingUtilities.invokeAndWait(new Runnable() {

                @Override
                public void run() {
                    DateFormat timeFormat = new SimpleDateFormat("HH:mm:ss");
                    Calendar cali = Calendar.getInstance();
                    cali.getTime();
                    String time = timeFormat.format(cali.getTimeInMillis());
                    System.out.println(timeFormat.format(cali.getTimeInMillis()));
                    jLabel4.setText(time);

                }
            });
        } catch (InvocationTargetException | InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
};

// This will invoke the timer every second
timer.scheduleAtFixedRate(task, 1000, 1000);

OR 使用The Swing Timer

Answer 3

使用线程

new Thread(new Runnable
{
    public void run()
    {
        long start = System.currentTimeMillis();
        while (true)
        {
            long time = System.currentTimeMillis() - start;
            int seconds = time / 1000;
            SwingUtilities.invokeLater(new Runnable() {
                 public void run()
                 {
                       label.setText("Time Passed: " + seconds);
                 }
            });
            try { Thread.sleep(100); } catch(Exception e) {}
        }
    }
}).start();

Answer 4

试试这个：

            Timer timer = new Timer("Display Timer");

            TimerTask task = new TimerTask() {
                @Override
                public void run() {
                   // Task to be executed every second

                    DateFormat timeFormat = new SimpleDateFormat("HH:mm:ss");
                    Calendar cali = Calendar.getInstance();
                    cali.getTime();
                    String time = timeFormat.format(cali.getTimeInMillis());
                    System.out.println(timeFormat.format(cali.getTimeInMillis()));
                    jLabel4.setText(time);
                }
            };

           // This will invoke the timer every second
            timer.scheduleAtFixedRate(task, 1000, 1000);

每秒显示时间

4 个答案: