Sample flutter beginner simple counter code

 import 'package:flutter/material.dart';

/*void main() {

  runApp(const MyApp());

}

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

*/

class MyApp extends StatelessWidget {

  const MyApp({Key? key}) : super(key: key);

  @override

  Widget build(BuildContext context) {

    return MaterialApp(

      title: 'Flutter Demo',

      theme: ThemeData(

        primarySwatch: Colors.blue,

      ),

      home: const MyHomePage(title: 'Flutter Demo Home Page'),

    );

  }

}

class MyHomePage extends StatefulWidget {

  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override

  State<MyHomePage> createState() => _MyHomePageState();

}

class _MyHomePageState extends State<MyHomePage> {

  int _counter = 0;

  void _incrementCounter() {

    setState(() {

      _counter++;

    });

  }

  @override

  Widget build(BuildContext context) {

    return Scaffold(

      appBar: AppBar(

        title: Text(widget.title),

      ),

      body: Center(

        child: Column(

          mainAxisAlignment: MainAxisAlignment.center,

          children: <Widget>[

            const Text(

              'You have pushed the button this many times:',

            ),

            Text(

              '$_counter',

              style: Theme.of(context).textTheme.headline4,

            ),

          ],

        ),

      ),

      floatingActionButton: FloatingActionButton(

        onPressed: _incrementCounter,

        tooltip: 'Increment',

        child: const Icon(Icons.add),

      ), // This trailing comma makes auto-formatting nicer for build methods.

    );

  }

}