reset dropdown menu flutter - flutter

Question

how to reset dropdonw to defult value after press button ?
i am trying to press button to reset dropdownmune to its defualt
class drawarScreen extends StatelessWidget {
const drawarScreen({super.key});
#override
Widget build(BuildContext context) {
List<String> list = <String>['One', 'Two', 'Three', 'Four'];
String? dropdownValue;
return Scaffold(
body: Column(children:[
DropdownButton<String>(
hint: Text('moammed'),
value: dropdownValue,
icon: const Icon(Icons.arrow_downward),
elevation: 16,
style: const TextStyle(color: Colors.deepPurple),
underline: Container(
height: 2,
color: Colors.deepPurpleAccent,
),
onChanged: (String? value) {
// This is called when the user selects an item.
setstate({
dropdownValue = value!;
});
},
items: list.map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
);
},
ElevatedButton(
onPress:(){
setstate({
dropdownValue='';
});
},child: Text("reste");
)
]);
}
}
i am trying to press button to reset dropdownmune to its defualt
resat dropdown menu in flutter

Answer 1

You need to put null value instead of empty string
setstate({
dropdownValue = null ;
});
If you like to have other than null, put it there.
And make sure to have StatefulWidget and variables outside the build method.
Full widget
class drawarScreen extends StatefulWidget {
const drawarScreen({super.key});
#override
State<drawarScreen> createState() => _drawarScreenState();
}
class _drawarScreenState extends State<drawarScreen> {
List<String> list = <String>['One', 'Two', 'Three', 'Four'];
String? dropdownValue;
#override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: [
DropdownButton<String>(
hint: Text('moammed'),
value: dropdownValue,
icon: const Icon(Icons.arrow_downward),
elevation: 16,
style: const TextStyle(color: Colors.deepPurple),
underline: Container(
height: 2,
color: Colors.deepPurpleAccent,
),
onChanged: (String? value) {
setState(() {
dropdownValue = value;
});
},
items: list.map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
),
ElevatedButton(
onPressed: () {
setState(() {
dropdownValue = null;
});
},
child: Text("Reset"))
],
),
);
}
}