创建倒计时器 - Java

问题描述

    Timer timer = new Timer();

    TimerTask task = new TimerTask(){
        public void run(){
            for (int i = 0; i <= 30; i++){
                lblTimer.setText("" + i);
            }
        }
    };
    timer.scheduleAtFixedRate(task, 0, 1000); //1000ms = 1sec

我创建了一个计时器，当我按下一个按钮时开始计时器运行的代码。任何人都可以帮我创建一个数到30的计时器吗？现在当我运行它时，在标签中设置文本30，但我希望它从0开始并计数到30。

I have created a timer that starts when I press a button and above is the code that run. Can anyone help me create a timer that counts to 30? Right now when I run it, sets the text "30" in the label but I want it to start at 0 and count until 30.

推荐答案

每次定时器运行时，它都会执行0到30之间的循环，因此只有在循环结束时才刷新UI。您需要将i保留在成员中并在每次调用 run 方法时更新它：

Each time your timer runs, it performs the loop from 0 to 30, thus the UI is refreshed only when the loop ends. You need to keep your i in a member and update it each time the run method is called as such:

    Timer timer = new Timer();

    TimerTask task = new TimerTask(){
        private int i = 0;
        public void run(){
            if (i <= 30) {
                lblTimer.setText("" + i++);
            }
        }
    };
    timer.scheduleAtFixedRate(task, 0, 1000); //1000ms = 1sec

当你达到i = 30时，你应该取消你的时间，否则它仍会每秒运行但没有真正的效果或需要。

Of course once your reach i = 30, you should cancel your times, otherwise it'll still run every second but with no real effect or need.

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