Flutter Hello World!

main.dart

//material package to use material widgets
import 'package:flutter/material.dart';

//Main method to run app
void main() => runApp(new MyApp());

//MyApp class
class MyApp extends StatelessWidget {
  
  @override
  Widget build(BuildContext context) {
    
    //Sinle container has text child
    return new Container(
      alignment: FractionalOffset.center,
      margin: const EdgeInsets.all(16.0),
      child: new Text(
        "Hello World!",
        textDirection: TextDirection.ltr,
      ),
    );
  }
}