使用Android在后台继续运行多个倒计时器和多个秒表

Question

我是Android和Java的新手，我一直在尝试解决计时器问题。请帮助 我有一个应用程序，用户可以创建多个倒计时器和多个秒表。 倒数计时器的示例代码如下所示（秒表也以类似的方式使用处理程序实现）。即使用户离开应用程序，我也希望定时器和秒表能够在后台运行。当用户再次返回应用程序时，应显示当前的计时器状态，而不是显示初始状态。 问题是我离开应用程序时我的计时器和秒表正在运行，但当用户返回应用程序时，结果不会发布到用户界面中。创建一个新实例，再次显示00:00:00的新计时器，而旧计时器继续在后台运行并继续运行而不能停止。在下面的代码中我有一个监听器发布结果在其回调中进入UI。这个界面在我的活动中实现。那么有人可以为此建议一个解决方案吗？

public class CountDownTimerService {

    public interface CounterTimeChangeListener {
        public void onCounterTimeChange(String time,Boolean counterFinished);
    }

    CounterTimeChangeListener listener;

    MyCountDownTimer myCountDownTimer;
    String output;
    int length;
    long startTime = 0;
    long currentTime = 0;
    long timeElapsed = 0;
    long timeRemaining = 0;
    long prevTimeRemaining = 0;


    public CountDownTimerService(int countDownFutureTime)
    {
        myCountDownTimer= new MyCountDownTimer(countDownFutureTime,1000);
        length=countDownFutureTime;
    }



    // code for countdown timer

    // this function format the time to hours seconds and minutes format
    public String formatTime(long mills)
    {
        output = "";
        long seconds = mills / 1000;
        long minutes = seconds / 60;
        long hours = minutes / 60;

        seconds = seconds % 60;
        minutes = minutes % 60;
        hours = hours % 60;

        String secondsD = String.valueOf(seconds);
        String minutesD = String.valueOf(minutes);
        String hoursD = String.valueOf(hours);


        if (seconds < 10)
            secondsD = "0" + seconds;
        if (minutes < 10)
            minutesD = "0" + minutes;

        if (hours < 10)
            hoursD = "0" + hours;

        output = hoursD +":" +minutesD +":"+ secondsD;

        return output;
    }

    // this function is called on start button click

    public void CountDownControl(int state) {

        if(state==0)
        {
            startTime = System.currentTimeMillis();
            myCountDownTimer.start();
        }

        else if(state==1)
        {
            // when the pause is clicked
            myCountDownTimer.cancel();
            currentTime = System.currentTimeMillis();
            timeElapsed = currentTime - startTime;
            if (prevTimeRemaining == 0)
                timeRemaining = length - timeElapsed;
            else
                timeRemaining = prevTimeRemaining - timeElapsed;
            prevTimeRemaining = timeRemaining;
            myCountDownTimer= new MyCountDownTimer(timeRemaining,1000);

            if (listener!=null) {
                listener.onCounterTimeChange(formatTime(timeRemaining), false);
            }

        }

    }

    // this function is called on reset button click
    public void resetInitial()
    {
        prevTimeRemaining = 0;
        myCountDownTimer.cancel();
        if (listener!=null) {
            listener.onCounterTimeChange(formatTime(length),false);
        }
        myCountDownTimer= new MyCountDownTimer(length,1000);
    }


    public class MyCountDownTimer extends CountDownTimer {

        public MyCountDownTimer(long millisInFuture, long countDownInterval) {
            super(millisInFuture, countDownInterval);
        }

        public void onTick (long millisUntilFinished) {

            // calls the fragment's callback function passing the time value
            Log.e("in counter","1");
            if (listener!=null) {
                Log.e("in counter","2");
                listener.onCounterTimeChange(formatTime(millisUntilFinished), false);
            }
        }

        public void onFinish() {
           /*
           * write code for an alarm when timer times out
           *
           * */
            prevTimeRemaining = 0;

            if (listener!=null) {
                listener.onCounterTimeChange(formatTime(length),true);
            }

            myCountDownTimer= new MyCountDownTimer(length,1000);
        }
    }


    public void setCounterTimeChangeListener(CounterTimeChangeListener listener) {
        this.listener = listener;
    }
}