Java Swing 计时器倒计时

问题描述

我必须制作一个倒计时程序，它也显示十分之一秒；例如从 10.0 秒倒计时，它应该显示 9.9s, 9.8s, ... 0.0s

I have to make a countdown program which also shows the tenths of a second;for example from a 10.0 second countdown, it should display 9.9s, 9.8s, ... 0.0s

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {

        timer.start();
        timer2.start();

}


Double timeLeft=5000; //5 seconds
Timer timer=new Timer(1,countDown);
Timer timer2=new Timer(1000,countDown2);
ActionListener countDown=new ActionListener()
{
    public void actionPerformed(ActionEvent e)
    {
        timeLeft--;
        SimpleDateFormat df=new SimpleDateFormat("mm:ss:S");
        jLabel1.setText(df.format(timeLeft));
        if(timeLeft<=0)
        {
            timer.stop();
        }
    }
};

实际情况是完成这 5 秒所需的时间超过 5 秒.

what happens is it's taking more than 5 seconds to finish the 5 seconds.

我将上面的代码与另一个 Timer 进行了比较

I compared the code above with another Timer

int timeLeft2=5;

ActionListener countDown2=new ActionListener()
{
    public void actionPerformed(ActionEvent e)
    {
        timeLeft2--;

        jLabel2.setText(String.valueOf(timeLeft2));
        if(timeLeft2<=0)
        {
            time2.stop();
        }
    }
};

他们不一样是自然的吗?

is it natural that they don't get the same?

推荐答案

更新标签可能需要超过 1 毫秒，这就是它跟不上的原因.如果您只需要显示十分之一秒，只需减少您的计时器更新频率.

Updating the label probably takes more that 1ms, which is why it can't keep up. If you only need to display tenths of a second, simply have your timer update less often.

ActionListener countDown=new ActionListener()
{
    public void actionPerformed(ActionEvent e)
    {
        timeLeft -= 100;
        SimpleDateFormat df=new SimpleDateFormat("mm:ss:S");
        jLabel1.setText(df.format(timeLeft));
        if(timeLeft<=0)
        {
            timer.stop();
        }
    }
};
Timer timer=new Timer(100, countdown);

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