Flutter 布洛克 & 肘

Question

I am following the tutorial here: https://resocoder.com/2020/08/04/flutter-bloc-cubit-tutorial/ .

When I reached the "Building with Cubit" part and in the main.dart , I have the following issue:

The errors I have:

[{
    "resource": "/d:/My Programs/learn_dart/weather_bloc/lib/main.dart",
    "owner": "_generated_diagnostic_collection_name_#1",
    "code": {
        "value": "type_argument_not_matching_bounds",
        "target": {
            "$mid": 1,
            "external": "https://dart.dev/diagnostics/type_argument_not_matching_bounds",
            "path": "/diagnostics/type_argument_not_matching_bounds",
            "scheme": "https",
            "authority": "dart.dev"
        }
    },
    "severity": 8,
    "message": "'dynamic' doesn't conform to the bound 'StateStreamableSource<Object?>' of the type parameter 'T'.\nTry using a type that is or is a subclass of 'StateStreamableSource<Object?>'.",
    "source": "dart",
    "startLineNumber": 13,
    "startColumn": 13,
    "endLineNumber": 13,
    "endColumn": 25,
    "relatedInformation": [
        {
            "startLineNumber": 13,
            "startColumn": 13,
            "endLineNumber": 13,
            "endColumn": 25,
            "message": "The raw type was instantiated as 'BlocProvider<dynamic>', and is not regular-bounded.",
            "resource": "/d:/My Programs/learn_dart/weather_bloc/lib/main.dart"
        }
    ]
}]

[{
    "resource": "/d:/My Programs/learn_dart/weather_bloc/lib/main.dart",
    "owner": "_generated_diagnostic_collection_name_#1",
    "code": "could_not_infer",
    "severity": 8,
    "message": "Couldn't infer type parameter 'T'.\n\nTried to infer 'dynamic' for 'T' which doesn't work:\n  Type parameter 'T' is declared to extend 'StateStreamableSource<Object?>' producing 'StateStreamableSource<Object?>'.\nThe type 'dynamic' was inferred from:\n  Parameter 'create' declared as     'T Function(BuildContext)'\n                     but argument is 'dynamic Function(BuildContext)'.\n\nConsider passing explicit type argument(s) to the generic.\n\n",
    "source": "dart",
    "startLineNumber": 13,
    "startColumn": 13,
    "endLineNumber": 13,
    "endColumn": 25
}]

[{
    "resource": "/d:/My Programs/learn_dart/weather_bloc/lib/main.dart",
    "owner": "_generated_diagnostic_collection_name_#1",
    "code": {
        "value": "undefined_method",
        "target": {
            "$mid": 1,
            "external": "https://dart.dev/diagnostics/undefined_method",
            "path": "/diagnostics/undefined_method",
            "scheme": "https",
            "authority": "dart.dev"
        }
    },
    "severity": 8,
    "message": "The method 'WeatherCubit' isn't defined for the type 'MyApp'.\nTry correcting the name to the name of an existing method, or defining a method named 'WeatherCubit'.",
    "source": "dart",
    "startLineNumber": 14,
    "startColumn": 30,
    "endLineNumber": 14,
    "endColumn": 42
}]

Can give me some hints on this?

Answer 1

From the log you provided

The method 'WeatherCubit' isn't defined for the type 'MyApp'.\nTry correcting the name to the name of an existing method, or defining a method named 'WeatherCubit'.

You forgot to import file with WeatherCubit definition.