仅在子类型扩展的类有一个可访问的无参数构造方法来初始化该类的状态时，才可以假定子类型有此职责。

The subtype may assume this responsibility only if the class it extends has an accessible no-arg constructor to initialize the class's state.

youdao

仅在子类型扩展的类有一个可访问的无参数构造方法来初始化该类的状态时，才可以假定子类型有此职责。

The subtype may assume this responsibility only if the class it extends has an accessible no-arg constructor to initialize the class's state.

youdao