我用kotlin流实现了一个很酷的定时器方法，所以你可以在ViewModel中实现它

    var countDownInit = 30
    fun countDownTimer() = flow<Int> {
    var time = countDownInit
    emit(time)
    while (true){
        time--
        delay(1000L)
        countDownInit = time
        emit(time)
    }
}

然后在你的activity或fragment中像这样调用这个函数

lifecycleScope.launch {
        lifecycle.repeatOnLifecycle(Lifecycle.State.STARTED){
                 viewModel.countDownTimer().collect{time->
                      //and update UI 
                     //and for the finish section you can just use this
                     this.cancel()          
                 }
        }
}

现在在应用程序生命周期的暂停阶段会出现崩溃，你总是有最新的时间

var futureMinDate = Date()
val sdf = SimpleDateFormat("yyyy-MM-dd", Locale.ENGLISH)
try {
    futureMinDate = sdf.parse("2019-08-22")
} catch (e: ParseException) {
    e.printStackTrace()
}

// Here futureMinDate.time Returns the number of milliseconds since January 1, 1970, 00:00:00 GM
// So we need to subtract the millis from current millis to get actual millis
object : CountDownTimer(futureMinDate.time - System.currentTimeMillis(), 1000) {
    override fun onTick(millisUntilFinished: Long) {
        val sec = (millisUntilFinished / 1000) % 60
        val min = (millisUntilFinished / (1000 * 60)) % 60
        val hr = (millisUntilFinished / (1000 * 60 * 60)) % 24
        val day = ((millisUntilFinished / (1000 * 60 * 60)) / 24).toInt()
        val formattedTimeStr = if (day > 1) "$day days $hr : $min : $sec"
        else "$day day $hr : $min : $sec"
        tvFlashDealCountDownTime.text = formattedTimeStr
    }

    override fun onFinish() {
        tvFlashDealCountDownTime.text = "Done!"
    }
}.start()

传递一个未来日期并将其转换为毫秒。

public class Scan extends AppCompatActivity {
int minute;
long min;
TextView tv_timer;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_scan2);
    tv_timer=findViewById(R.id.tv_timer);
    minute=Integer.parseInt("Your time in string form like 10");
    min= minute*60*1000;
    counter(min);
}
private void counter(long min) {
    CountDownTimer timer = new CountDownTimer(min, 1000) {
        public void onTick(long millisUntilFinished) {
            int seconds = (int) (millisUntilFinished / 1000) % 60;
            int minutes = (int) ((millisUntilFinished / (1000 * 60)) % 60);
            int hours = (int) ((millisUntilFinished / (1000 * 60 * 60)) % 24);
            tv_timer.setText(String.format("%d:%d:%d", hours, minutes, seconds));
        }
        public void onFinish() {
            Toast.makeText(getApplicationContext(), "Your time has been completed",
                    Toast.LENGTH_LONG).show();
        }
    };
    timer.start();
}

}

接口方式。

import android.os.CountDownTimer;

/**
 * Created by saikiran on 07-03-2016.
 */
public class CountDownTimerCustom extends CountDownTimer {

    private TimeTickListener mTickListener;
    private TimeFinishListener mFinishListener;
    private long millisUntilFinished;

    public CountDownTimerCustom(long millisInFuture, long countDownInterval) {
        super(millisInFuture, countDownInterval);

    }

    public void updateTickAndFinishListener(TimeTickListener tickListener) {
        mTickListener = tickListener;
    }

    public void updateFinishListner(TimeFinishListener listener) {
        mFinishListener = listener;
    }

    public long getCurrentMs() {
        return millisUntilFinished;
    }

    public int getCurrentSec() {
        return (int) millisUntilFinished / 1000;
    }

    @Override
    public void onTick(long millisUntilFinished) {
        this.millisUntilFinished = millisUntilFinished;
        if (mTickListener != null)
            mTickListener.onTick(millisUntilFinished);
    }

    @Override
    public void onFinish() {
        if (mTickListener != null)
            mTickListener.onFinished();
        mFinishListener.onFinished();
    }


    public interface TimeTickListener {
        void onTick(long mMillisUntilFinished);

        void onFinished();
    }

    public interface TimeFinishListener {
        void onFinished();
    }
}

下面是我在Kotlin中使用的解决方案

private fun startTimer()
{
    Log.d(TAG, ":startTimer: timeString = '$timeString'")

    object : CountDownTimer(TASK_SWITCH_TIMER, 250)
    {
        override fun onTick(millisUntilFinished: Long)
        {
            val secondsUntilFinished : Long = 
            Math.ceil(millisUntilFinished.toDouble()/1000).toLong()
            val timeString = "${TimeUnit.SECONDS.toMinutes(secondsUntilFinished)}:" +
                    "%02d".format(TimeUnit.SECONDS.toSeconds(secondsUntilFinished))
            Log.d(TAG, ":startTimer::CountDownTimer:millisUntilFinished = $ttlseconds")
            Log.d(TAG, ":startTimer::CountDownTimer:millisUntilFinished = $millisUntilFinished")
        }

        @SuppressLint("SetTextI18n")
        override fun onFinish()
        {
            timerTxtVw.text = "0:00"
            gameStartEndVisibility(true)
        }
    }.start()
}

// the count down timer


 new  CountDownTimer(30000, 1000)
         {
        @Override
        public void onTick(long l) {

        }
        @Override
        public void onFinish() {
        
                //on finish the count down timer finsih        
                         }
          
            }
        }

    }.start();