content: import 'package:flutter/material.dart';
  import 'package:flutter/gestures.dart';
  
  void main() {
    runApp(MaterialApp(
        title: 'Checkbox Widget Example',
        theme: ThemeData(
          primarySwatch: Colors.blue,
        ),
        home: Scaffold(
          appBar: AppBar(title: Text('Checkbox Widget Example'),),
          body: MyApp(),
        )
    ));
  }
  
  class MyApp extends StatefulWidget {
    @override
    _MyAppState createState() => _MyAppState();
  }
  
  class _MyAppState extends State<MyApp> {
  
    int _rValue = 0;
  
    void method(int value){
      setState(() {
        _rValue = value;
      });
      print(value);
    }
  
    @override
    Widget build(BuildContext context) {
      return Padding(
        padding: const EdgeInsets.all(16.0),
        child: Container(
          decoration: BoxDecoration(
              border: Border.all(color: Colors.purple)
          ),
          child: Column(
            children : [
              RadioListTile(
                value: 1,
                groupValue: _rValue,
                onChanged: (value){
                  method(value);
                },
                title: Text('Flutter'),
                subtitle: Text('SubTitle'),
                secondary: Icon(Icons.favorite),
                controlAffinity: ListTileControlAffinity.trailing,
                activeColor: Colors.purple,
                selected: _rValue==1?true:false,
              ),
              RadioListTile(
                value: 2,
                groupValue: _rValue,
                onChanged: (value){
                  method(value);
                },
                title: Text('iOS'),
                subtitle: Text('SubTitle'),
                secondary: Icon(Icons.info_outline_sharp),
                controlAffinity: ListTileControlAffinity.trailing,
                activeColor: Colors.purple,
                selected: _rValue==2?true:false,
              ),
              RadioListTile(
                value: 3,
                groupValue:_rValue,
                onChanged: method,
                title: Text('Android'),
                subtitle: Text('SubTitle'),
                secondary: Icon(Icons.android),
                controlAffinity: ListTileControlAffinity.trailing,
                activeColor: Colors.purple,
                selected: _rValue==3?true:false,
              )
           ]
          ),
        ),
      );
    }
  }
  
  