What does it mean <> in method?

Question

I have this method

  @override
  Response<BodyType> convertResponse<BodyType, SingleItemType>(
      Response response) {
    final Response dynamicResponse = super.convertResponse(response);
    final BodyType customBody =
        _convertToCustomObject<SingleItemType>(dynamicResponse.body);
    return dynamicResponse.replace<BodyType>(body: customBody);
  }

What does it mean <BodyType> and <BodyType, SingleItemType> in this method?

Answer 1

These are called generics in Dart (in fact, they are called the same in other similar programming languages).

The main idea behind generics is that you could reuse the same code without relying on a specific data/return type. Imagine List in Dart. You could have a list of integers (List<int>), a list of strings (List<String>), a list of your custom objects (List<CustomType>) - the type is not hardcoded and it could be adjusted based on your needs.

Also, you could say that it would be easier just to use dynamic or Object types that would cover most of these cases. However, generics brings you type safety, and the method type itself becomes a parameter.

Here is the official documentation about generics.