how to change the state inside FutureBuilder - flutter

Question

i just need when the user open the screen the notification icon button change when he click, it's value is coming from shared preferences. the problem is the icon is never changed!
the initState code:
#override
void initState() {
super.initState();
_isActiveNotification = _notificationGetState();
}
_notificationGetState function is:
//getting notification on/off
Future<bool> _notificationGetState() async {
final SharedPreferences _prefs = await SharedPreferences.getInstance();
return _prefs.getBool('notification') ?? true;
}
_isActiveNotification variable is:
late Future<bool> _isActiveNotification;
the class of the notification icon button is:
class _NoificationActivationButton extends StatefulWidget {
_NoificationActivationButton();
#override
_NoificationActivationButtonState createState() =>
_NoificationActivationButtonState();
}
class _NoificationActivationButtonState
extends State<_NoificationActivationButton> {
#override
Widget build(BuildContext context) {
return FutureBuilder<bool>(
//function haveing the return value
future: _isActiveNotification,
builder: (context, snapshot) {
bool data = snapshot.data!;
return IconButton(
icon: Icon(
data
? Icons.notifications_active_outlined
: Icons.notifications_off_outlined,
color: Colors.white,
size: 40,
),
onPressed: () {
setState(() {
data = !data;
});
},
);
});
}

Answer 1

just call setstate
onPressed: () {
data = !data;
// just call setstate((){});
},

Answer 2

Make data a global state.
NOTE: I'm only assuming that you will only call _notificationGetState once (in initState).
Sample...
class _NoificationActivationButtonState
extends State<_NoificationActivationButton> {
final bool _isOtherVersion = true;
late Future<bool> _isActiveNotification;
bool? _data;
#override
void initState() {
super.initState();
_isActiveNotification = _notificationGetState();
}
//getting notification on/off
Future<bool> _notificationGetState() async {
final SharedPreferences _prefs = await SharedPreferences.getInstance();
return _isOtherVersion
? _prefs.getBool('notification') ?? true
: _data = _prefs.getBool('notification') ?? true;
}
#override
Widget build(BuildContext context) {
return FutureBuilder<bool>(
//function haveing the return value
future: _isActiveNotification,
builder: (context, snapshot) {
if (snapshot.connectionState != ConnectionState.done) {
return const CircularProgressIndicator();
}
if (_isOtherVersion && _data == null) {
_data = snapshot.data;
}
return IconButton(
icon: Icon(
_data!
? Icons.notifications_active_outlined
: Icons.notifications_off_outlined,
color: Colors.white,
size: 40,
),
onPressed: () => setState(() => _data = !_data!),
);
},
);
}
}