根据数据库中的日期在android中设置计时器

Question

我是android新手。我有一个应用程序需要在textview中显示存储在数据库中的数据（这是一个时间值，例如40小时）。

我想将40（在我的情况下）的值倒数到零，并且当它达到零时应该开始报警。

Answer 1

您可以使用CountDownTimer对数值进行倒计时，如下所示：

  final MyCounter timer = new MyCounter(600000, 1000); //add your time

 ...
   public class MyCounter extends CountDownTimer
    {

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

        @Override
        public void onFinish()
        {
            Log.i("debug","Timer Completed");

        }

        @Override
        public void onTick(long millisUntilFinished)
        {

            tv.setText("Timer : " + (millisUntilFinished/60000) + " " + "minutes remaining.");
        }

  }

对于警报部分，您可以使用AlarmManager。这是一个tutorial。

希望它有所帮助！

Answer 2

  

只需将剩余时间转换为秒（从db获取小时值并将其转换为秒，在我的情况下，我将在几秒钟内获得时间）

public class CountDownActivity extends Activity {

    int time,initStart,startPointTime,hh,mm,ss,millis;
    TextView txtSecond;
    TextView txtMinute;
    TextView txtHour;
    TextView txtDay;
    Handler handler;
    long seconds =40*60*60;
    Runnable updater;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            // TODO Auto-generated method stub
            super.onCreate(savedInstanceState);


    txtSecond=(TextView)findViewById(R.id.cntSecond);
            txtMinute=(TextView)findViewById(R.id.cntMinute);
            txtHour=(TextView)findViewById(R.id.cntHour);
            txtDay=(TextView)findViewById(R.id.cntDay);

                    handler= new Handler();
            initStart = (int) SystemClock.elapsedRealtime();

             updater = new Runnable() {

                public void run() {
                    int sec,minute,hour,day;
                    long  diff = seconds;
                    System.out.println(diff);
                    if (diff >= 1) {
                        sec =  (int) (diff%60);
                    } else {
                        sec=00;
                    }
                    txtSecond.setText("" +sec);
                    diff = diff/60;
                    System.out.println(diff);
                    if (diff >= 1) {
                        minute =  (int) (diff%60);
                    } else {
                        minute=00;
                    }
                    txtMinute.setText("" +minute);
                    diff = diff/60;
                    if (diff >= 1) {
                        hour =  (int) (diff%24);
                    } else {hour = 00; }
                    txtHour.setText("" +hour);
                    diff = diff/24;
                    if (diff >= 1) {
                        day =  (int) diff;
                    } else { day =00; }
                    txtDay.setText("" +day);
                    seconds=seconds-1;


                    handler.postDelayed(this, 1000);
                }
            };

            handler.post(updater);
}

> //and don't forget to removeCallback on destroy

    @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        handler.removeCallbacks(updater);
    }
}