An interface that has a covariant type parameter enables its methods to return more derived types than those specified by the type parameter.

如果接口具有协变类型形参，则允许其方法返回与接口类型形参指定的派生类型相比，派生程度更大的类型的实参。

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An interface that has a covariant type parameter enables its methods to return more derived types than those specified by the type parameter.

如果接口具有协变类型形参，则允许其方法返回与接口类型形参指定的派生类型相比，派生程度更大的类型的实参。

youdao