Change the value of the radio button when selected - flutter

Question

Ive got a list of strings
List<String> answerOptions=['Apple','Orange','Grapes','Kiwi'];
and I've created a custom radio button file named QuizRadioButton
class QuizRadioButton extends StatefulWidget {
final String label;
final void Function(dynamic) onChanged;
const QuizRadioButton(
{required this.label, required this.onChanged, Key? key})
: super(key: key);
#override
_QuizRadioButtonState createState() => _QuizRadioButtonState();
}
class _QuizRadioButtonState extends State<QuizRadioButton> {
int? _value = 0;
#override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.all(16.0),
child: Row(
children: [
Radio<int>(
value: 1,
groupValue: _value,
onChanged: (value) => setState(() => _value = value),
),
Text(widget.label, style: Theme.of(context).textTheme.headline3),
],
),
);
}
}
I've used this radio button class and I've populated 4 radio buttons using the list mentioned above
Widget content(BuildContext context){
return Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
children: <Widget>[
Text('which fruit of these are red in color ?'),
SizedBox(height: 30.0,),
for(int i=0;i<answerOptions.length;i++)Container(
child:QuizRadioButton(label: answerOptions[i], onChanged: (value){}) ,
)
],
),
);
}
and I get the output as
Right now we can select all 4 radio buttons at once, what I want is if I want to pick apple, the radio button with apple as the label should be true and others as false. Please help

Answer 1

int groupVal=0;
Implementation:
Widget content(BuildContext context){
return Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
children: <Widget>[
Text('which fruit of these are red in color ?'),
SizedBox(height: 30.0,),
for(int i=0;i<answerOptions.length;i++)
Container(
child:QuizRadioButton(label: answerOptions[i], onChanged: (value){
setState(() {
groupVal=value;
});
}, index: i, groupVal: groupVal) ,
)
],
),
),
}
Your QuizRadioButton:
class QuizRadioButton extends StatefulWidget {
final String label;
final void Function(dynamic) onChanged;
int index,groupVal;
QuizRadioButton(
{required this.label, required this.groupVal, required this.onChanged, required this.index, Key? key})
: super(key: key);
#override
_QuizRadioButtonState createState() => _QuizRadioButtonState();
}
class _QuizRadioButtonState extends State<QuizRadioButton> {
#override
Widget build(BuildContext context) {
return Padding(
padding: const EdgeInsets.all(16.0),
child: Row(
children: [
Radio<int>(
value: widget.index,
groupValue: widget.groupVal,
onChanged: widget.onChanged,
),
Text(widget.label, style: Theme.of(context).textTheme.headline3),
],
),
);
}
}