Hello world in flutter

main_2.dart

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: "FlutterApp",
      home: Scaffold(
        appBar: AppBar(
           title: Text("FlutterHello"),
        ),
        body: Center(
          child: Text("Hello World!"),
        ),
      ),
    );
  }
}