Remove callback for handler not work

Question

I have written a handler that calls the method every time interval. I want to remove that handler in on destroy(). The code i use as follows, In Oncreate()

private final Handler _handler = new Handler();
public int DATA_INTERVAL = 30 * 1000;
Runnable getData;
 getData = new Runnable()
        {
            @Override
            public void run()
            {
                     recieveData();
            }
        };

 _handler.postDelayed(getData, DATA_INTERVAL);

and in ondestroy(), i use,

_handler.removeCallbacks(getData);

But removecallbacks not work. It calls after exiting the activity.

You could call `_handler.removeCallbacksAndMessages()` without any parameter. It removes everything in the callbacks and messages stack — Sergi Juanola, Aug 16 '12 at 06:50
@Kor it gives error when calling _handler.removeCallbacksAndMessages() without parameter. — Shalini, Aug 16 '12 at 07:07
_handler.removeCallbacksAndMessages(null) use this line and let me know if it works. — Randroid, Aug 16 '12 at 08:35
check this link http://stackoverflow.com/questions/5883635/how-to-remove-all-callback-from-a-handler — Randroid, Aug 16 '12 at 09:41
@Raghav thanks. but its works now by using this link http://stackoverflow.com/questions/5844308/removecallbacks-not-stopping-runnable — Shalini, Aug 16 '12 at 10:08

score 10 · Accepted Answer · edited May 23 '17 at 10:31

10

removeCallbacks(Runnable r):

Remove any pending posts of Runnable r that are in the message queue.

so removeCallbacks(..) only stops pending messages (Runnables) not currently running runnable so if you want to stop currently running Runable then use a Boolean varaible for Stoping Thread when user Exit from your app.

see this post for removeCallbacks not stopping runnable

edited May 23 '17 at 10:31

Community

1
1

answered Aug 16 '12 at 06:49

ρяσѕρєя K

132,198
53
198
213

5

Wrong. Notice he's calling `removeCallbacks` from `onDestroy` which runs in the main thread. So either a pending Runnable runs first and then `onDestroy` cancels all future callbacks, or `onDestroy` runs first and cancels all future callbacks so no Runnable would run after that. He has a different problem. – Mister Smith Mar 15 '16 at 16:22

score 0 · Answer 2 · answered Mar 15 '16 at 16:27

You are not showing the most important part of the code which is the receiveData method. As you said you are running the task periodically, you must be calling again postDelayed from inside that method to reschedule the task. Probably background threads involved as you cannot do networking on the main thread.

You most likely have a race condition when exiting the Activity. onDestroy runs first and then the task is posted again.

score 0 · Answer 3 · answered Jul 08 '19 at 06:53

0

You should use

handler.removeCallbacksAndMessages(null);

Then all handler callbacks will removed.

answered Jul 08 '19 at 06:53

Mimo Saha

61
4

Remove callback for handler not work

3 Answers3

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