How To Add Onchnaged Radio Button Listener Using Flutter App

import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  MyHomePageState createState() {
    return new MyHomePageState();
  }
}

class MyHomePageState extends State<MyHomePage> with SingleTickerProviderStateMixin {
  int _currentIndex = 1;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.green[700],
        title: Text("Onchnaged Radio Button Listener"),
      ),
      body: Column(
        children: <Widget>[
          Expanded(
            child: Center(
              child:
              Text(_currentIndex == 1 ? "Radio Checked" : "Radio UnChecked",
                  style: TextStyle(
                    fontSize: 20.0,
                    fontWeight: FontWeight.bold,
                  )),
            ),
          ),
          Expanded(
              child: Container(
                height: 350.0,
                child: Column(
                  children: [
                    RadioListTile(
                      activeColor: Colors.green[800],
                      groupValue: _currentIndex,
                      title: Text("Radio Button Text"),
                      value: 1,
                      onChanged: (val) {
                        setState(() {
                          _currentIndex = val;
                        });
                      },
                    ),
                  ],
                ),
              )),
        ],
      ),
    );
  }
}