Flutter: Timer timer cannot end previous session with timer.cancel()?

Question

when I call timer.cancel (), the clock stops working. But when calling back to start a new session, I discover that the _u variable in the old session still counts from itself and parallel with new one.

Please help !

startTime(60);   
timer.cancel();# It worked.
timer = null;   
startTime(60);# but when recall. It working with 2 session. (old and new)
//Call timer.cancel() _u variable stop at 40.

//Recall startTime() _u variable counts with 2 session (40) and (60)  


startTime(reset){
          int _u = reset;
          const oneSec = const Duration(seconds: 1);
                  timer = Timer.periodic(
                    oneSec,
                    (Timer timer) => setState(
                    () {
                        if (_u < 1) {
                          timer.cancel();
                          // call my handle
                    } else {
                          _u = _u -1;
                          if(_u <0){
                            timer?.cancel();
                          }
                        }
                      },
                    ),
                  );

It not useful for me. In my case I wanna closed previous session. (timer cancel and _u stop counts down). — Son Tran
– Son Tran, Commented Nov 25, 2020 at 12:02

Teddichiiwa · Accepted Answer · 2020-11-25 17:01:40Z

1

Cancel the timer if it is not null. The code below was tested

void startTime(reset) {
    int _u = reset;
    const oneSec = const Duration(seconds: 1);

    if (timer != null) {
      timer.cancel();
    }

    timer = Timer.periodic(oneSec, (Timer t) {
      if (_u < 1) {
        t.cancel();
        // call my handle
      } else {
        _u = _u - 1;
        print(_u);
        if (_u < 0) {
          t?.cancel();
        }
      }
    });
  }

answered Nov 25, 2020 at 17:01

Teddichiiwa

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