I want to know what's the main difference between using super.key and (Key? key) : super(key: key) in a flutter app, I mean I know they both set key from the super widgets, but why there is 2 types of them, and which is preferred to use.

CodePudding user response：

super.key is the new syntax, made available in Dart 2.17, which first came with Flutter 3.0. Details are at the release notes: https://dart.dev/guides/whats-new#may-11-2022-217-release

The new syntax is much shorter and cleaner, but you'll need to understand both forms for years to come.