Im trying to create simple camera app in flutter and i run into this error. Whenever I switch to the 'Scan'(Camera) page i get the following message LateInitializationError: Field '_initializeController@28060535' has not been initialized..From what i can see the error occures within the startCamera function. If i hot-reload the app, everything works as it should. Here's my code
Main.dart (only the widgdet part)

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        body: PageView(
          controller: _controller,
          onPageChanged: _onPageChanged,
          children: const [
            ScanPage(title: 'scan'),
            SettingsPage(title: 'settings'),
          ],
        ),
        bottomNavigationBar: BottomNavigationBar(
            items: const <BottomNavigationBarItem>[
              BottomNavigationBarItem(icon: Icon(Icons.camera), label: 'Scan'),
              BottomNavigationBarItem(
                  icon: Icon(Icons.settings), label: 'Settings')
            ],
            selectedItemColor: Colors.white,
            currentIndex: _selectedIndex,
            onTap: _onItemTapped));
}

scan.dart

class ScanPage extends StatefulWidget {
      const ScanPage({super.key, required this.title});
    
      final String title;
    
      @override
      State<ScanPage> createState() => _ScanPageState();
    }
    
class _ScanPageState extends State<ScanPage> {
      late List<CameraDescription> cameras;
      late CameraController _controller;
      late Future<void> _initializeController;                                                
                                                                                                                      
      void startCamera() async {
        cameras = await availableCameras();
        _controller = CameraController(cameras[1], ResolutionPreset.high,
            enableAudio: false, imageFormatGroup: ImageFormatGroup.jpeg);
        _initializeController = _controller.initialize();
        await _initializeController;
      }
    
      @override
      void initState() {
        super.initState();
        startCamera();
      }
    
      @override
      void dispose() {
        _controller.dispose();

        super.dispose();
      }
    
      @override
      Widget build(BuildContext context) {
        return Scaffold(
            extendBody: true,
            resizeToAvoidBottomInset: true,
            floatingActionButtonLocation: 
            FloatingActionButtonLocation.centerFloat,
            body: Stack(
              alignment: AlignmentDirectional.bottomEnd,
              children: [
                FutureBuilder<void>(
                  future: _initializeController,
                  builder: (context, snapshot) {
                    print(snapshot.connectionState == ConnectionState.done);
                    if (snapshot.connectionState == ConnectionState.done) {
                      return CameraPreview(_controller);
                    } else {
                      return const Center(child: CircularProgressIndicator());
                    }
                  },
                ),
              ],
            ));
      }

CodePudding user response：

The _initializeController depends on other future method like availableCameras. Therefore there are some delay to initialize the _initializeController. You can use main startCamera as Future in this case.

  Future<void> startCamera() async {
    ......
  }

  late final future = startCamera();

And use

FutureBuilder<void>(
    future: future,