// 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'),),
    );
  }

}