How to cancel a handler before time in Android code?

Question

I create 1 minute delayed timer to shutdown service if it's not completed. Looks like this:

private Handler timeoutHandler = new Handler();

inside onCreate()

timeoutHandler.postDelayed(new Runnable()
        {
            public void run()
            {
                Log.d(LOG_TAG, "timeoutHandler:run");

                DBLog.InsertMessage(getApplicationContext(), "Unable to get fix in 1 minute");
                finalizeService();
            }
        }, 60 * 1000);

If I get job accomplished before this 1 minute - I would like to get this delayed thing cancelled but not sure how.

score 48 · Accepted Answer · answered May 04 '11 at 15:13

48

You can't really do it with an anonymous Runnable. How about saving the Runnable to a named variable?

Runnable finalizer = new Runnable()
    {
        public void run()
        {
            Log.d(LOG_TAG, "timeoutHandler:run");

            DBLog.InsertMessage(getApplicationContext(), "Unable to get fix in 1 minute");
            finalizeService();
        }
    };
timeoutHandler.postDelayed(finalizer, 60 * 1000);

...

// Cancel the runnable
timeoutHandler.removeCallbacks(finalizer);

answered May 04 '11 at 15:13

Brian Dupuis

8,136
3
25
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1

tiemoutHandler.removeCallbacksAndMessages(null); to remove all callbacks to handle an anonymous Runnable. (as mentioned in AbdelHady answer) – Lorenz03Tx Jul 22 '16 at 13:45
2

That's dandy as long as you don't mind removing ALL callbacks, not just this one. OP asked about removing a particular callback. – Brian Dupuis Jul 26 '16 at 20:34

score 15 · Answer 2 · answered Dec 24 '14 at 16:47

15

If you don't want to keep a reference of the runnable, you could simply call:

timeoutHandler.removeCallbacksAndMessages(null);

The official documentation says:

... If token is null, all callbacks and messages will be removed.

answered Dec 24 '14 at 16:47

AbdelHady

9,334
8
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83

score 10 · Answer 3 · answered May 04 '11 at 15:13

You might want to replace use of postDelayed with use of sendMessageDelayed like so:

private Handler timeoutHandler = new Handler(){
    @Override
    public void handleMessage(Message msg)
    {
            switch (msg.what){
        case 1:
            ((Runnable)msg.obj).run();
            break;
        }
    }
};

Then post a Message:

Message m = Message.obtain();
m.what = 1;
m.obj = new Runnable(){
            public void run()
            {
                Log.d(LOG_TAG, "timeoutHandler:run");

                DBLog.InsertMessage(getApplicationContext(), "Unable to get fix in 1 minute");
                finalizeService();
            }
        };
timeoutHandler.sendMessageDelayed(m, 60 * 1000);

and then cancel:

timeoutHandler.removeMessages(1);

No tracking of the runnable necessary.

score 2 · Answer 4 · answered May 04 '11 at 15:10

2

If I get job accomplished before this 1 minute - I would like to get this delayed thing cancelled but not sure how.

Use Handler.removeCallbacks(yourRunnable).

answered May 04 '11 at 15:10

Wroclai

26,835
7
76
67

How to cancel a handler before time in Android code?

4 Answers4

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