import 'package:flutter/material.dart';

void main() {
  runApp(RadioButton());
}

class RadioButton extends StatefulWidget {
  @override
  _RadioButtonState createState() => _RadioButtonState();
}

enum Gender { Male, Female }

class _RadioButtonState extends State<RadioButton> {
  var val = -1;
  Gender? _gender = Gender.Male;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        appBar: AppBar(
          title: Text(
            "RadioButton Example",
          ),
        ),
        body: Container(
          child: Column(
            children: [
              ListTile(
                title: const Text('Male'),
                leading: Radio<Gender>(
                  value: Gender.Male,
                  groupValue: _gender,
                  onChanged: (Gender? value) {
                    setState(() {
                      _gender = value;
                    });
                  },
                ),
              ),
              ListTile(
                title: const Text('Female'),
                leading: Radio<Gender>(
                  value: Gender.Female,
                  groupValue: _gender,
                  onChanged: (Gender? value) {
                    setState(() {
                      _gender = value;
                    });
                  },
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}