flutter - 如何使用 ListTile 记住和突出显示选定的抽屉项目？

Question

我正在使用 ListTile 在抽屉导航上显示项目，但我很难创建 isSelected Color 并使用它将其应用于 onTap 但不断收到有关索引的错误并且应用程序无法识别onTap 上的 isSelected bool 值:

  for(int i = 0; i < isSelected.length; i++){
                    setState(() {
                       if (index == i) {
                          isSelected[index] = true;
                       } else {                               //the condition to change the highlighted item
                          isSelected[i] = false;
                       }
                     });

这是我在 Flutter 中创建的 Navigation Drawer，如果您可以提供有关如何在 _createDrawerItem 小部件中获取 'isSelected' 并将其应用到抽屉的建议。我已经为抽屉项目设置了“isSelected”的真假，但似乎无法将其应用于 onTap。

class NavDraw extends StatefulWidget {
  @override
  _NavDrawState createState() => _NavDrawState();

}

class _NavDrawState extends State<NavDraw> {

  @override
  void initState() {

    super.initState();

  }

  Widget build(BuildContext context) {
    return Drawer(
      child: Container(
        child: ListView(
          children: <Widget> [
          Container(
              height: 100.0,
              color: Color(0xff2B4DB9),
              child: DrawerHeader(
                  margin: EdgeInsets.fromLTRB(0, 0, 0, 0),
                  padding: EdgeInsets.zero,
                  decoration: BoxDecoration(
                      image: DecorationImage(
                          fit: BoxFit.none,
                          image:  AssetImage('images/drawer_header.png')))),
            ),
          _createDrawerItem(
        icon: Icons.timer,
    text: 'Timer',
      isSelected: true,
      onTap: () =>
      Navigator.pushReplacementNamed(context, Routes.home)),
        _createDrawerItem(
        icon: Icons.history,
        text: 'History',
            isSelected: false,
            onTap: () =>
            Navigator.pushReplacementNamed(context, Routes.history)),
      _createDrawerItem(
        icon: Icons.help,
        text: 'Help & Support',
          isSelected: false,
          onTap: () =>
            Navigator.pushReplacementNamed(context, Routes.help_and_support)),
      _createDrawerItem(
        icon: Icons.rate_review,
        text: 'Write a Review',
          isSelected: false,
          onTap: () =>
            Navigator.pushReplacementNamed(context, Routes.write_a_review)),
      Divider(),
    ],
    ),
      ),
    );
  }
}


Widget _createDrawerItem(
{IconData icon, String text, GestureTapCallback onTap, bool isSelected}) {
  return Ink(
    color: isSelected ? Color(0xffE3EAFF) : Colors.transparent,
    child: ListTile(
      selected: true,
      hoverColor: Colors.white,
      title: Row(
      children: <Widget>[
      Icon(icon),
      Padding(
      padding: EdgeInsets.only(left: 8.0),
      child: Text(text),
      )
      ],
      ),
      onTap: onTap,
      ),
  );
}

Answer 1

您可以在下面复制粘贴运行完整代码
您可以使用 selectedIndex 来控制
在 isSelected 中传递 selectedIndex == 0 或 selectedIndex == 1 ..etc
代码片段

int selectedIndex = 0;
...
_createDrawerItem(
                icon: Icons.timer,
                text: 'Timer',
                isSelected: selectedIndex == 0,
                onTap: () {
                  setState(() {
                    selectedIndex = 0;
                  });

                  Navigator.pushReplacementNamed(context, "/page0");
                }),

工作演示

完整代码

import 'package:flutter/material.dart';

class NavDraw extends StatefulWidget {
  @override
  _NavDrawState createState() => _NavDrawState();
}

int selectedIndex = 0;

class _NavDrawState extends State<NavDraw> {

  @override
  Widget build(BuildContext context) {
    return Drawer(
      child: Container(
        child: ListView(
          children: <Widget>[
            Container(
              height: 100.0,
              color: Color(0xff2B4DB9),
              child: DrawerHeader(
                  margin: EdgeInsets.fromLTRB(0, 0, 0, 0),
                  padding: EdgeInsets.zero,
                  decoration: BoxDecoration(
                      image: DecorationImage(
                          fit: BoxFit.none,
                          image: NetworkImage(
                              'https://picsum.photos/250?image=9')))),
            ),
            _createDrawerItem(
                icon: Icons.timer,
                text: 'Timer',
                isSelected: selectedIndex == 0,
                onTap: () {
                  setState(() {
                    selectedIndex = 0;
                  });

                  Navigator.pushReplacementNamed(context, "/page0");
                }),
            _createDrawerItem(
                icon: Icons.history,
                text: 'History',
                isSelected: selectedIndex == 1,
                onTap: () {
                  setState(() {
                    selectedIndex = 1;
                  });

                  Navigator.pushReplacementNamed(context, "/page1");
                }),
            _createDrawerItem(
                icon: Icons.help,
                text: 'Help & Support',
                isSelected: selectedIndex == 2,
                onTap: () {
                  setState(() {
                    selectedIndex = 2;
                  });

                  Navigator.pushReplacementNamed(context, "/page2");
                }),
            _createDrawerItem(
                icon: Icons.rate_review,
                text: 'Write a Review',
                isSelected: selectedIndex == 3,
                onTap: () {
                  setState(() {
                    selectedIndex = 3;
                  });

                  Navigator.pushReplacementNamed(context, "/page3");
                }),
            Divider(),
          ],
        ),
      ),
    );
  }
}

Widget _createDrawerItem(
    {IconData icon, String text, GestureTapCallback onTap, bool isSelected}) {
  return Ink(
    color: isSelected ? Color(0xffE3EAFF) : Colors.transparent,
    child: ListTile(
      selected: true,
      hoverColor: Colors.white,
      title: Row(
        children: <Widget>[
          Icon(icon),
          Padding(
            padding: EdgeInsets.only(left: 8.0),
            child: Text(text),
          )
        ],
      ),
      onTap: onTap,
    ),
  );
}

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      initialRoute: '/page0',
      routes: {
        '/page0': (context) => Page0(),
        '/page1': (context) => Page1(),
        '/page2': (context) => Page2(),
        '/page3': (context) => Page3(),
      },
    );
  }
}

class Page0 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        drawer: NavDraw(),
        appBar: AppBar(
          title: Text("page 0"),
        ),
        body: Text("page 0"));
    ;
  }
}

class Page1 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        drawer: NavDraw(),
        appBar: AppBar(
          title: Text("page 1"),
        ),
        body: Text("page 1"));
    ;
  }
}

class Page2 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        drawer: NavDraw(),
        appBar: AppBar(
          title: Text("page 2"),
        ),
        body: Text("page 2"));
    ;
  }
}

class Page3 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        drawer: NavDraw(),
        appBar: AppBar(
          title: Text("page 3"),
        ),
        body: Text("page 3"));
    ;
  }
}

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 _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      drawer: NavDraw(),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}