title: TimerTask stops firing in Service
body: <p>I need to have a Service running in Android that stores a value to database every so often.  How often is based on user preferences, and also if other events have happened, which can be as often as 30 seconds or up to 30 minutes.</p>
  
  <p>This is not something that is hidden from the user and in fact the user should probably be aware its running.  As such I think a foreground service is probably the best approach.</p>
  
  <p>I have a foreground service running, with a TimerTask that calculates how often it needs to fire.  That Service is 'sticky' so it should stick around and it low on resources the OS should start it back up after a while.</p>
  
  <p>My problem is that the TimerTask seems to stop running after a while when the the app is backgrounded.</p>
  
  <p>Here is my service:</p>
  
  <pre><code>public class TimerService extends Service {
  
      private static final String LOG_NAME = TimerService.class.getName();
      private Timer timer;
      private final Handler timerHandler = new Handler();
  
      @Override
      public void onCreate() {
          super.onCreate();
  
          Notification notification = new NotificationCompat.Builder(this, "MY_APP_CHANNEL_ID")
                  .setContentTitle("My Timer Service")
                  .setContentText("Background timer task")
                  .setSmallIcon(R.drawable.timer)
                  .build();
  
          startForeground(1, notification);
      }
  
      @Override
      public int onStartCommand(Intent intent, int flags, int startId) {
          startTimer();
          return START_STICKY;
      }
  
      @Override
      public void onDestroy() {
          super.onDestroy();
          stopTimer();
      }
  
  
      @Override
      public IBinder onBind(Intent intent) {
          return null;
      }
  
      private void stopTimer() {
          if (timer != null) {
              timer.cancel();
              timer = null;
          }
      }
  
      private void startTimer() {
          stopTimer();
  
          timer = new Timer();
  
          long frequency = // calculate frequency
          long delay = // calculate delay
          timer.scheduleAtFixedRate(new MyTimerTask(), delay, frequency);
      }
  
      private void saveToDatabase() {
          // Save some stuff to the database...
          if (some condition) {
            // might need to reschedule timer delay and frequency.
            startTimer();
          }
      }
  
      private class MyTimerTask extends TimerTask {
          @Override
          public void run() {
              timerHandler.post(new Runnable() {
                  @Override
                  public void run() {
                    onTimerFire();
                  }
              });
          }
  
          private void onTimerFire() {
            try {
              saveToDatabase();
            } catch (Exception e) {
              Log.e(LOG_NAME, "Error in onTimerFire", e);
            }    
          }
      }
  }
  </code></pre>
  
  <p>Should this work?  IE can I have a simple Timer in a foreground Service that fires continuously until that service is stopped?  If so is there a bug in my code?</p>
  
  <p>I chose a Timer to try to keep it simple, I only ever need one timer running and I wanted it to be able to reschedule easily.  I do realize that I could try a Handler, ScheduledThreadPoolExecutor, or even an AlarmManager.  I thought an AlarmManager might be overkill and a drain on resources if it is firing a ton.  Not to mention rescheduling.</p>