import 'package:flutter/material.dart';

import 'pages/Tabs.dart';

void main() {

  runApp(MyApp());

}

class MyApp extends StatelessWidget {

  @override

  Widget build(BuildContext context) {

    // TODO: implement build

    return MaterialApp(

      home: Tabs(),

    );

  }

}

import 'package:flutter/material.dart';

import 'tabs/Home.dart';

import 'tabs/Category.dart';

import 'tabs/Setting.dart';

class Tabs extends StatefulWidget {

  Tabs({Key key}) : super(key: key);

  _TabsState createState() => _TabsState();

}

class _TabsState extends State<Tabs> {

  int _currentIndex = ;

  List _pageList=[

    HomePage(),

    CategoryPage(),

    SettingPage()

  ];

  @override

  Widget build(BuildContext context) {

    return Scaffold(

      appBar: AppBar(

        title: Text('Flutter Demo'),

      ),

      bottomNavigationBar: BottomNavigationBar(

          currentIndex: this._currentIndex,

          onTap: (int index) {

            // print(index);

            setState(() {

              this._currentIndex = index;

            });

          },

          iconSize: 36.0,

          type: BottomNavigationBarType.fixed,

          fixedColor: Colors.red,

          items: [

            BottomNavigationBarItem(icon: Icon(Icons.home), title: Text('首页')),

            BottomNavigationBarItem(

                icon: Icon(Icons.category), title: Text('分类')),

            BottomNavigationBarItem(

                icon: Icon(Icons.settings), title: Text('设置')),

          ]),

      body: this._pageList[this._currentIndex],

    );

  }

}

import 'package:flutter/material.dart';

class HomePage extends StatelessWidget {

  const HomePage({Key key}) : super(key: key);

  @override

  Widget build(BuildContext context) {

    return Container(

      child: Text('首页'),

    );

  }

}

import 'package:flutter/material.dart';

class CategoryPage extends StatelessWidget {

  const CategoryPage({Key key}) : super(key: key);

  @override

  Widget build(BuildContext context) {

    return Container(

      child: Text('分类')

    );

  }

}

import 'package:flutter/cupertino.dart';

class SettingPage extends StatelessWidget {

  const SettingPage({Key key}) : super(key: key);

  @override

  Widget build(BuildContext context) {

    return Container(

      child: Text('设置'),

    );

  }

}