how to show switch in flutter

switch.dart

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  const MyApp({Key key}) : super(key: key);

  @override
  State<StatefulWidget> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  bool _switchVal = true;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        home: Scaffold(
            body: Column(
      children: <Widget>[
        Container(
            margin: EdgeInsets.only(top: 45),
            child: Switch(
              onChanged: (bool value) {
                setState(() => this._switchVal = value);
              },
              value: this._switchVal,
            ))
      ],
    )));
  }
}