关于Flutter中的StatefulWidget小优化 一文写法报错

[superiums]

关于Flutter中的StatefulWidget小优化 一文，按你的写法：
abstract class usefulStatefulWidget extends _Stateful with State<StatefulWidget> {}
报错：The class 'State' can't be used as a mixin because it extends a class other than Object.

[AweiLoveAndroid]

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