AlertDialog function runs on everypage in flutter - flutter

Question

theAlertDialog in this code should run only when the user access the Account page (obviously), but while testing it, it runs on the Account page and all the next pages, and it is even duplicated, i mean when i head from Account page to another page the AlertDialog will be displayed twice
class Account extends StatefulWidget {
#override
_AccountState createState() => _AccountState();
}
class _AccountState extends State<Account> {
#override
Widget build(BuildContext context) {
Future.delayed(Duration.zero, () => FirstRun(context));
return Scaffold(
//there are alot of widgets here like drawer but all of it works fine
//i don't think its necessary to write it
);
}
FirstRun(BuildContext context) async {
SharedPreferences prefs = await SharedPreferences.getInstance();
bool first = (prefs.getBool('firstUse'));
print('Pressed $first');
if (first == null) {
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
backgroundColor: Color(0xaa6b6b6b),
elevation: 10,
content: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Text(
'first run dialog',
overflow: TextOverflow.ellipsis,
maxLines: 6,
style: TextStyle(
color: Colors.white,
fontSize: 24,
),
textAlign: TextAlign.center,
),
Container(
child: MaterialButton(
onPressed: () {
prefs.setBool('firstUse', false);
Navigator.of(context).pop();
print('Pressed $first');
},
child: Text(
'ok',
),
))
],
),
);
},
);
}
}
}

Answer 1

maybe it happens because you start showing the alert on build method. try to show it on initState method of the Account widget.
class _AccountState extends State<Account> {
#override
initState() {
Future.delayed(Duration.zero, () => FirstRun(this.context));
super.initState();
}
#override
Widget build(BuildContext context) {
return Scaffold(
//there are alot of widgets here like drawer but all of it works fine
//i don't think its necessary to write it
);
}

Answer 2

as a work around i call the next page using Navigator.Replace instead of Navigator.push , but i dont think this is a real solution