BottomNavigationBar + BottomNavigationBarItem导航的另外一种用法

import 'package:flutter/material.dart';
import 'News.dart';
import 'Video.dart';
import 'Chat.dart';
import 'MyId.dart';

class AppTwo extends StatelessWidget {
  @override
  Widget build(BuildContext context) => MaterialApp(home: Home());
}

class Home extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => _HomeState();
}

class _HomeState extends State<Home> {
  int _currentIndex = ;
  final List<Widget> _children = [
    NewsPage(),
    VideoPage(),
    ChatPage(),
    MyIdPage()
  ];

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
//      appBar: AppBar(
//        title: Text("第二种方式"),
//        centerTitle: true,
//      ),
      body: _children[_currentIndex],
//      CupertinoTabBar 是IOS分格
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: _currentIndex,
        onTap: onTabTapped,
        items: [
          BottomNavigationBarItem(
              title: new Text("Home"), icon: new Icon(Icons.home)),
          BottomNavigationBarItem(
              title: new Text("List"), icon: new Icon(Icons.list)),
          BottomNavigationBarItem(
              title: new Text("Message"), icon: new Icon(Icons.message)),
        ],
      ),
    );

  }

  void onTabTapped(int index) {
    setState(() {
      _currentIndex = index;
    });
  }
}

import 'package:flutter/material.dart';
import 'Guide.dart';

void main() => runApp(new AppTwo());