Flutter - Using Timer and .cancel() function - flutter

Question

*** UPDATE ***
I have a problem. When I use a Timer in Flutter and cancel() it afterwards, but as soon the cancel method is triggered, nothing happens.
var counter = 0;
Timer.periodic(const Duration(milliseconds: 50), (timer) {
developer.log('Actual counter ' + counter.toString());
counter++;
if (counter == 5) {
developer.log('TIMER DONE');
timer.cancel();
}
});
developer.log('This comes afterwards');
Expected out put:
Actual counter 0
Actual counter 1
Actual counter 2
Actual counter 3
Actual counter 4
TIMER DONE
This comes afterwards
The Output:
Actual counter 0
Actual counter 1
Actual counter 2
Actual counter 3
Actual counter 4
TIMER DONE
normally I should see a message 'this is afterwards' in the console, but it seems that with the cancel the complete method will be canceled.
Many thanks in advance.

Answer 1

Update: perform operation end of timer.
You need to add logic inside if condition to perform operation.
if (counter == firmwareList.length) {
timer.cancel();
developer.log('This comes afterwards'); //here
}
});
Here is an widget example
class TimerF extends StatefulWidget {
const TimerF({super.key});
#override
State<TimerF> createState() => _TimerFState();
}
class _TimerFState extends State<TimerF> {
var counter = 0;
Timer? timer;
bool isTimerActive = true;
#override
void initState() {
super.initState();
timer = Timer.periodic(const Duration(seconds: 1), (timer) {
print('Still timer');
if (counter == 5) {
timer.cancel();
isTimerActive = false;
}
counter++;
setState(() {});
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: [
Text("current value ${counter}"),
if (timer?.isActive == false) Text("Timer isnt active"),
if (isTimerActive == false) Text("Timer isnt active $isTimerActive"),
],
),
);
}
}
I can't see any increment on counter on current snippet. that's why counter remains 0 and doesnt meet the condition to cancel the timer.
Perhaps it will be
var counter = 0;
Timer.periodic(const Duration(milliseconds: 50), (timer) {
print('Still timer');
if (counter == 5) {
timer.cancel();
}
counter++; //increment the value
print('this is afterwards');
});

Answer 2

Here is a fully working example using a Timer
Timer? timer;
startTimer() {
var counter = 0;
timer = Timer.periodic(const Duration(milliseconds: 50), (timer) {
counter += 1;
print('Actual step $counter');
if(counter==5) {
cancelTimer();
}
});
}
cancelTimer() {
timer?.cancel();
print('this is afterwards');
//do something here
}
When you startTimer(), here is the output
Actual step 1
Actual step 2
Actual step 3
Actual step 4
Actual step 5
this is afterwards