Flutter基础

import ‘package:flutter/material.dart‘;

/*void main() {
  runApp(MyApp());
}*/

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

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You‘ll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn‘t reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
        // This makes the visual density adapt to the platform that you run
        // the app on. For desktop platforms, the controls will be smaller and
        // closer together (more dense) than on mobile platforms.
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: new Scaffold(
        appBar: new AppBar(
          title: new Text("First Flutter Demo"),
        ),
        body: new Center(
          child: new Text("It is body"),
        ),
      ),
    );
  }
}

void main() => runApp(MyApp());   
等同于
void main() {
  runApp(MyApp());
}

优点：能使用最新代码
缺点：编译出错，前一天代码还能编译，今天编译出错情况

final _suggestions = <WordPair>[];

在Dart语言中使用下划线前缀标识符，会强制其变成私有的。