Android timer in service - how to stop and start

Question

I have read many posts but cannot find an answer to my specific question.

The service below works well. I can start it. It starts. I can stop it. It stops. I can restart it with a new interval. This works too. When I then stop it, it will not stop. In onDestroy this is the timer = null case. If I insert timer.cancel in onDestroy within the timer = null case, I then get a crash for acting on a null pointer. Yet, it is still running as illustrated by the log output!

Here is the log output if helpful (after the last "noOutRows" it just keeps running)

E/ timer:  startservice
E/ timer:  timeInterval 1000
E/ timer:  isNotNull
E/ timer:  no noOutRows 1503945704743
E/ timer:  no noOutRows 1503945705712
E/ timer:  no noOutRows 1503945706714
E/ timer:  no noOutRows 1503945707713
E/ timer:  no noOutRows 1503945708712
E/ timer:  stopservice
E/ timer:  stop - isNotNull
E/ timer:  startservice
E/ timer:  timeInterval 5000
E/ timer:  isNull
E/ timer:  no noOutRows 1503945744406
E/ timer:  no noOutRows 1503945749407
E/ timer:  no noOutRows 1503945754407
E/ timer:  stopservice
E/ timer:  stop - isNull
E/ timer:  no noOutRows 1503945759407
E/ timer:  no noOutRows 1503945764407
E/ timer:  no noOutRows 1503945769773

Here is my code

    public class LocalService extends Service
{
    public Integer timeInterval = 1000;
    private static Timer timer = new Timer();
    public IBinder onBind(Intent arg0)
    {
        return null;
    }

    @Override
    public void onCreate()
    {
        super.onCreate();
    }
    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        Log.e(" timer"," startservice");
        int newTimeInterval = intent.getIntExtra("time_interval", -99);
            timeInterval = newTimeInterval;
            Log.e(" timer ", " timeInterval " + timeInterval);
            if (timer == null){
                Log.e(" timer"," isNull");
                Timer timer = new Timer();
                timer.scheduleAtFixedRate(new mainTask(), 0, timeInterval);
            } else {
                Log.e(" timer"," isNotNull");
                timer.scheduleAtFixedRate(new mainTask(), 0, timeInterval);
            }
        return START_STICKY;
    }
    private class mainTask extends TimerTask
    {
        public void run()
        {
            logHandler.sendEmptyMessage(0);
        }
    }
    public void onDestroy()
    {
        Log.e(" timer"," stopservice");
        if (timer != null) {
            Log.e(" timer"," stop - isNotNull");
            timer.cancel();
            timer = null;
        } else {
            Log.e(" timer"," stop - isNull");
        }
        super.onDestroy();
    }
    private final Handler logHandler = new Handler()
    {
        @Override
        public void handleMessage(Message msg)
        {
            int maxRows = MainActivity.Cache.alls.size()-1;
            if (maxRows > 0) {
                Log.e(" timer ", " outRows " + maxRows + " " + MainActivity.Cache.alls.get(maxRows).toString());
            } else {
                Log.e(" timer ", " no noOutRows " + MainActivity.utcNow().getTime());
            }
        }
    };
}

Isn't this expected? https://stackoverflow.com/q/9093271/1531971 — , Aug 28 '17 at 19:54
Thanks. Good question. I am not very familiar with START_STICKY. However, I will try the Runnable approach below. — Frank Zappa, Aug 28 '17 at 21:27

score 0 · Answer 1 · answered Aug 28 '17 at 19:28

For some reason I don't remember everyone agreed not to use Timers in Android, they went for the Runnable/Handler combo. It goes like this

private static final int delay = 1000;
private final Handler handler = new Handler();

Runnable runnable = new Runnable() {
    @Override
    public void run() {
        yourAdvancedScheduledLogic();//pre or post as you wish
        if(!yourExitCondition()) {
            handler.postDelayed(this, delay);
        }
    }
};

and

runnable.run();//stars the timer

Thanks. I created a class and put the code above in it. Now I just need to handle start/stop and passing in the delay value. — Frank Zappa, Aug 28 '17 at 21:27

Android timer in service - how to stop and start

1 Answers1