how can i change a RadioListTile button selection state after it has been initialized in flutter - flutter

Question

I have created a RadioListTile based on a list of string items in an initStat function. But i could not get the radio button to change when it is being selected. If it were in a build function i could just call setState and it would have marked it as selected.
How can i mark it as selected when i have created it at the beginning of the code. below here is the code i have tried, it actually print the selected radioTile value but i could not get it to change the selected state or the radio button selection.
List<String> list = ['Satisfied', 'Not Satisfied', 'Very Satisfied','Neutral'];
String _radioGroupValue = '';
int selectedRadioTile = 0;
void initState() {
super.initState();
selectedRadioTile = 0;
setState(() {
for (int n = 0; n < list.length; n++) {
answersRadio.add(RadioListTile(
value: n,
groupValue: _radioGroupValue,
onChanged: (val) {
print('selected Radio index $val');
setSelectedRadioTile(val);
setState(() {
});
},
title: Text(list[n]),
selected: _radioGroupValue == list[n] ? true : false,
));
}
});
}
setSelectedRadioTile(int val){
setState(() {
selectedRadioTile = val;
});
}
child: Column(children: answersRadio,)

Answer 1

class Example extends StatefulWidget {
const Example({Key? key}) : super(key: key);
#override
State<StatefulWidget> createState() {
return _Examplestate();
}
}
class _Examplestate extends State<Example> {
List<String> list = [
'Satisfied',
'Not Satisfied',
'Very Satisfied',
'Neutral'
];
String? _radioGroupValue;
List<RadioListTile> answersRadio = [];
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Stateful Widget'),
),
body: Column(
children: [
for (var n in list)
RadioListTile<String>(
value: n,
groupValue: _radioGroupValue,
onChanged: (val) {
_radioGroupValue = val;
setState(() {});
},
title: Text(n),
toggleable: true,
selected: _radioGroupValue == n,
)
],
),
);
}
}

Answer 2

set int _groupValue = -1. define value for value : parameter according your need
Radio(
materialTapTargetSize:
MaterialTapTargetSize.shrinkWrap,
visualDensity: VisualDensity.comfortable,
activeColor: AppTheme.primaryColor,
value: 1,
groupValue: _groupValue,
onChanged: (value) {
setState(() {
_groupValue = value as int;
});
},
),