The argument type 'void Function(ConnectivityResult)' can't be assigned to the parameter type 'void Function(List<ConnectivityResult>)?'

The argument type 'void Function(ConnectivityResult)' can't be assigned to the parameter type 'void Function(List<ConnectivityResult>)?'. how can I solve it ?

The error indicates that the _updateConnectionStatus method is being treated as if it returns a List<ConnectivityResult>, which is not correct. The _updateConnectionStatus method returns a ConnectivityResul indicating the current connectivity status.

There seems to be a misunderstanding in the method signature for _updateConnectionStatus.

late StreamSubscription subscription;
  StreamSubscription<ConnectivityResult>? connectivitySubscription;
  StreamSubscription? internetSubscription;
  bool hasInternet = false;

  @override
  void initState(){
    super.initState();
    subscription = Connectivity().onConnectivityChanged.listen(_updateConnectionStatus);
    internetSubscription = InternetConnectionChecker().onStatusChange.listen((status) { 
      final hasInternet = status == InternetConnectionStatus.connected;
      setState(() => this.hasInternet = hasInternet);
    });
  }

  @override
  void dispose() {
    // Cancel the connectivity subscription when the controller is closed
    connectivitySubscription?.cancel();
    super.dispose();
  }

  void _updateConnectionStatus (ConnectivityResult result) {
    final hasInternet = result != ConnectivityResult.none;
    final message = hasInternet
        ? result == ConnectivityResult.mobile
            ? 'You are connected to mopile network'
            : 'You are connected to mopile network'
        : 'You have no internet';

    // Only check for the none case, which indicates no connectivity
    if (!hasInternet) {
      Get.rawSnackbar(
          messageText: Text('PLEASE CONNECT TO THE INTERNET $message',
              style: const TextStyle(color: Colors.white, fontSize: 14)),
          isDismissible: false,
          duration: const Duration(days: 1),
          backgroundColor: Colors.red[400]!,
          icon: const Icon(
            Icons.wifi_off,
            color: Colors.white,
            size: 35,
          ),
          snackStyle: SnackStyle.GROUNDED);
    } else {
      if (Get.isSnackbarOpen) {
        Get.closeCurrentSnackbar();
      }
    }
  }

Solution

The error message is correct. You're passing your _updateConnectionStatus method, which takes a ConnectivityResult as the parameter, to the listen callback of onConnectivityChanged, which is a stream of List<ConnectivityResult>.

On the previous versions of the connectivity_plus package, the onConnectivityChanged stream emits a ConnectivityResult, in which your method could be passed to it. However, the update 6.0.x introduced some breaking changes, one of them is that the onConnectivityChanged stream now emits List<ConnectivityResult> instead.

Your option is to either downgrade the connectivity_plus package to 5.x.x, or adapt your _updateConnectionStatus method to accept a List<ConnectivityResult> as the parameter.