Run a function AFTER that the alertbox has been dismissed - flutter

Question

I already read countless links like this one but it does not help.
The use case is very simple, I want to run a function AFTER the alert box has been dismissed.
void dummyFunc() {
sleep(Duration(seconds:3));
print("done");
}
Future<bool> displayDialog() async {
return showDialog<bool>(
context: context,
barrierDismissible: false, // user must tap button!
builder: (BuildContext context) {
return AlertDialog(
title: Text('AlertDialog Title'),
content: SingleChildScrollView(
child: ListBody(
children: <Widget>[
Text('This is a demo alert dialog.'),
Text('Would you like to approve of this message?'),
],
),
),
actions: <Widget>[
FlatButton(
child: Text('Decline'),
onPressed: () {
Navigator.of(context).pop(false);
},
),
FlatButton(
child: Text('Approve'),
onPressed: () {
Navigator.of(context).pop(true);
},
),
],
elevation: 24.0,
shape:RoundedRectangleBorder(),
);
},
);
}
var button = AnimatedOpacity(
opacity: 1.0,
duration: Duration(milliseconds: 500),
child: FloatingActionButton(
tooltip: 'Start',
child: Icon(iconShape),
onPressed: () async {
bool shouldUpdate = await displayDialog();
print(shouldUpdate);
if (shouldUpdate)
dummyFunc();
})
);
But the alert dialog is dismissed 3sd after.
Kindly let me know what I am doing wrong, Thank you~

Answer 1

I think this is happening because you are using sleep. Instead of that use Future delay.
void dummyFunc() {
print("done");
}
If you don't want delay, then you can also remove this future, this function will executed after dialog box dismissed.
Sleep will hold the process, that’s why you are facing this error.

Answer 2

Solved it thanks to Viren who gave me a good intuition, Timer works also nicely if you are not using a loop:
void dummyFunc() {
Timer(Duration(seconds: 3), () {
print("done");
});
}
Edit: Actually Viren's answer work better with loops! This can work also. Just avoid sleep. Spent 3h on this, now I hate sleep().