有什么办法可以在状态class中调用状态class吗？

Question

main.dart

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

final GlobalKey<ScaffoldState> _scaffoldKey = GlobalKey<ScaffoldState>();

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'A',
      theme: ThemeData(
        fontFamily: 'Bookman',
        primarySwatch: Colors.indigo,
      ),
      home: MyHomePage(title: 'A'),
    );
  }
}

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

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
  //navigationBar createNavState() => navigationBar();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    SizeConfig().init(context);
    return Scaffold(
        key: _scaffoldKey,
        endDrawer: Container(
          child: Column(
            children: [],
          ),
        ),
        appBar: PreferredSize(
          preferredSize: Size.fromHeight(SizeConfig.screenHeight / 16),
          child: AppBar(
            leading: Icon(Icons.menu),
            title: new Text(
              'A',
              style: TextStyle(fontSize: 16.0, fontWeight: FontWeight.normal),
            ),
            actions: [
              Padding(
                padding: EdgeInsets.symmetric(horizontal: 16),
                child: Icon(Icons.search),
              ),
              Icon(Icons.person),
            ],
          ),
        ),
        body: Column(
          children: [
            Row(
              children: [
                Container(
                  width: SizeConfig.screenWidth,
                  height: SizeConfig.screenHeight * (1 / 16),
                  decoration: BoxDecoration(
                      border: Border.all(color: Colors.grey[200])),
                )
              ],
            ),
            Row(
              children: [
                Column(
                  children: [
                    Container(
                      width: SizeConfig.screenWidth / 7,
                      height: SizeConfig.screenHeight * (13 / 16),
                      decoration: BoxDecoration(
                          border: Border.all(color: Colors.grey[200])),
                    )
                  ],
                ),
                Column(
                  children: [
                    Row(
                      children: [Container(child: Text("CALL IN HERE!") )],
                    ),
                    Row(children: [
                      Container(
                        width: SizeConfig.screenWidth * (6 / 7),
                        height: SizeConfig.screenHeight * (1 / 16),
                        decoration: BoxDecoration(
                            border: Border.all(color: Colors.grey[200])),
                      )
                    ]),
                    Row(
                      children: [myDataTable()],
                    )
                  ],
                )
              ],
            )
          ],
        ));
  }


}

navigationBar.dart

var _logo = new Image.asset('image/**.ico', width: 40, height: 50);

Future dwln() async {
  const url = "https://**/download.php";
  if (await canLaunch(url))
    await launch(url);
  else
    
    throw "Could not launch $url";
}

//class navigationBar extends StatefulWidget {}

class navigationBarState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Container(
      width: SizeConfig.screenWidth * (6 / 7),
      height: SizeConfig.screenHeight * (1 / 16),
      decoration: BoxDecoration(border: Border.all(color: Colors.grey[200])),
      child: Center(
        child: Column(
          children: [
            Row(
              children: [
                Text(
                  "New   ",
                  style: TextStyle(fontSize: 13),
                ),
                IconButton(
                  icon: Icon(Icons.add),
                  color: Colors.pinkAccent,
                  onPressed: () {
                    which = "new";
                    endDrawer();
                  },
                  iconSize: 15,
                ),
                Text(
                  "Exit grid view   ",
                  style: TextStyle(fontSize: 13),
                ),
                IconButton(
                  icon: Icon(Icons.edit),
                  color: Colors.pinkAccent,
                  onPressed: () {
                    setState(() {
                      selectedUsers.length = 0;
                      if (getir == true) {
                        getir = false;
                      } else {
                        getir = true;
                      }
                    });
                  },
                  iconSize: 15,
                ),
                Text(
                  "Export to EXCEL    ",
                  style: TextStyle(fontSize: 13),
                ),
                IconButton(
                  icon: Icon(Icons.save),
                  color: Colors.pinkAccent,
                  onPressed: () {
                    dwln();
                  },
                  iconSize: 15,
                ),
                Text(
                  "Import EXCEL file   ",
                  style: TextStyle(fontSize: 13),
                ),
                IconButton(
                  icon: Icon(Icons.import_contacts),
                  color: Colors.pinkAccent,
                  onPressed: () {},
                  iconSize: 15,
                ),
                if (editlabel == true)
                  Row(
                    children: [
                      Text(
                        "Edit   ",
                        style: TextStyle(fontSize: 13),
                      ),
                      IconButton(
                        icon: Icon(Icons.edit),
                        color: Colors.pinkAccent,
                        onPressed: () {
                          setState(() {
                            which = "update";
                          });

                          endDrawer();
                        },
                        iconSize: 15,
                      ),
                    ],
                  )
              ],
            ),
          ],
        ),
      ),
    );
  }
}

大家好，我想在 main.dart 文件中调用 navigationBarState class。但是由于“状态”，它不允许这样做。它说“参数类型 'navigationBarState' 无法分配给参数类型 'Widget'。”。但是我需要 State extend 才能使用 setState。有解决办法吗？

Answer 1

看来你只有状态。您还需要 StatefulWidget。我不确定你为什么把它注释掉，但你需要把它放回去。

至少你需要：

class navigationBar extends StatefulWidget {
  navigationBar ({Key? key}) : super(key: key);

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

然后您可以在小部件树中放置一个 navigationBar，而不是状态本身。

状态 class 本身必须使用小部件，因为它是通用参数：

class navigationBarState extends State<navigationBar>

有什么办法可以在状态class中调用状态class吗？

Is there any way to call state class in state class?

state

setstate

dart

flutter