具有页面视图的BottomNavigationBar不会动画化到索引页面

Question

我尝试在BottomNavigationBar上添加三个页面以导航到索引页面，我的代码的实现非常干净，没有错误，但是BottomNavigationBar不会更改为其他页面，意味着selecten BottomNavigationBar项的颜色更改为所选页面，而没有任何更改DEBUG控制台上的错误，这是我的代码

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

  int bottomSelectedIndex = 0;

  List<BottomNavigationBarItem> buildBottomNavBarItems() {
    return [
      BottomNavigationBarItem(
          icon: new Icon(Icons.home),
          title: new Text('Red')
      ),
      BottomNavigationBarItem(
        icon: new Icon(Icons.search),
        title: new Text('Blue'),
      ),
      BottomNavigationBarItem(
          icon: Icon(Icons.info_outline),
          title: Text('Yellow')
      )
    ];
  }

  PageController pageController = PageController(
    initialPage: 0,
    keepPage: true,
  );

  Widget buildPageView() {
    return PageView(
      controller: pageController,
      onPageChanged: (index) {
        pageChanged(index);
      },
      children: <Widget>[
        Red(),
        Blue(),
        Yellow(),
      ],
    );
  }

  @override
  void initState() {
    super.initState();
  }

  void pageChanged(int index) {
    setState(() {
      bottomSelectedIndex = index;
    });
  }

  void bottomTapped(int index) {
    setState(() {
      bottomSelectedIndex = index;
      pageController.animateToPage(index, duration: Duration(milliseconds: 500), curve: Curves.ease);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: buildPageView(),
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: bottomSelectedIndex,
        onTap: (index) {
          bottomTapped(index);
        },
        items: buildBottomNavBarItems(),
      ),
    );
  }
  }

Answer 1

您可以在下面复制粘贴运行完整代码您可以使用PageView.builder代码段

List<Widget> listWidget = [Red(), Yellow(), Blue()];
...
return PageView.builder(
      controller: pageController,
      onPageChanged: (index) {
        pageChanged(index);
      },
      itemCount: listWidget.length,
      itemBuilder: (BuildContext context, int index) {
        return listWidget[index];
      },
    );

工作演示

完整代码

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  List<Widget> listWidget = [Red(), Yellow(), Blue()];
  int bottomSelectedIndex = 0;

  List<BottomNavigationBarItem> buildBottomNavBarItems() {
    return [
      BottomNavigationBarItem(
          icon: new Icon(Icons.home), title: new Text('Red')),
      BottomNavigationBarItem(
        icon: new Icon(Icons.search),
        title: new Text('Blue'),
      ),
      BottomNavigationBarItem(
          icon: Icon(Icons.info_outline), title: Text('Yellow'))
    ];
  }

  PageController pageController = PageController(
    initialPage: 0,
    keepPage: true,
  );

  Widget buildPageView() {
    return PageView.builder(
      controller: pageController,
      onPageChanged: (index) {
        pageChanged(index);
      },
      itemCount: listWidget.length,
      itemBuilder: (BuildContext context, int index) {
        return listWidget[index];
      },
    );
  }

  @override
  void initState() {
    super.initState();
  }

  void pageChanged(int index) {
    setState(() {
      bottomSelectedIndex = index;
    });
  }

  void bottomTapped(int index) {
    setState(() {
      bottomSelectedIndex = index;
      pageController.animateToPage(index,
          duration: Duration(milliseconds: 500), curve: Curves.ease);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: buildPageView(),
      bottomNavigationBar: BottomNavigationBar(
        currentIndex: bottomSelectedIndex,
        onTap: (index) {
          bottomTapped(index);
        },
        items: buildBottomNavBarItems(),
      ),
    );
  }
}

class Red extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("Red");
  }
}

class Blue extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("Blue");
  }
}

class Yellow extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text("Yellow");
  }
}