// 这一行
debugShowCheckedModeBanner: false,
import 'package:flutter/material.dart';
void main()=>runApp(
  MaterialApp(
    // 这一行
    debugShowCheckedModeBanner: false,
    home:MyApp(),
  )
);
class MyApp extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('UI布局'),),
    );
  }
}