Question

你能告诉我为什么这段代码不起作用？在我看来它应该工作。它在控制台1中写入后停止。我想连续显示秒数，但仅当我发表评论temp = passedTime然后脚本出错时它才有效

import java.util.ArrayList;

class Timer {

    private static long temp = 0;

    public static void main(String [] args){

        ArrayList<Integer> list = new ArrayList<>();

        long startTime = System.currentTimeMillis()/1000;

        for (int i=1; i<=1000000; i++) {
            list.add(i);
            long pasedTime = System.currentTimeMillis()/1000 - startTime;
            if (temp != passedTime) {
                temp = passedTime;
                System.out.println(pasedTime);
            }
        }
    }
}

Answer 1

我写了一个关于如何在第二个线程上创建计时器的示例，请参见此处：

public class TimerAppExample {
    public static class Timer implements Runnable {
        private int timer = 5000;
        private long startTimer = 0;
        private SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss:SSS");

        @Override
        public void run() {

            startTimer = System.currentTimeMillis();
            System.out.println("Started timer at " + simpleDateFormat.format(new Date(startTimer)));
            do {
                try {
                    Thread.sleep(1000);
                    long newTime = System.currentTimeMillis();
                    System.out.println("Timer event occurred after " + (newTime - startTimer) + " miliseconds at " + simpleDateFormat.format(new Date(newTime)));
                    timer -= (newTime-startTimer);
                    startTimer = newTime;
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            } while(timer > 0);
            System.out.println("stopped timer at " + simpleDateFormat.format(new Date(startTimer)));
        }
    }


    private void execute() {
        Timer timer = new Timer();
        Thread thread = new Thread(timer);
        System.out.println("Starting timer");
        thread.start();
        try {
            thread.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("Timer app ended");
    }

    public static void main(String[] args) {
        TimerAppExample timerAppExample = new TimerAppExample();
        timerAppExample.execute();
    }
}

输出：

Starting timer
Started timer at 2015-05-16 12:40:31:104
Timer event occurred after 1001 miliseconds at 2015-05-16 12:40:32:105
Timer event occurred after 1000 miliseconds at 2015-05-16 12:40:33:105
Timer event occurred after 1000 miliseconds at 2015-05-16 12:40:34:105
Timer event occurred after 1000 miliseconds at 2015-05-16 12:40:35:105
Timer event occurred after 1000 miliseconds at 2015-05-16 12:40:36:105
stopped timer at 2015-05-16 12:40:36:105
Timer app ended

Java - 我试图制作一个计时器

1 个答案: