java访问修饰符

Question

Modifier    Class   Package Subclass    World
public      Y          Y       Y           Y
protected   Y          Y       Y           N
no modifier Y          Y       N           N
private     Y          N       N           N 

没有修饰符(默认修饰符)只能从同一个包访问，不能从子类访问。

如果子类在同一个包中怎么办？子类可以访问它吗？

Answer 1

What if the subclass is in the same package? Will it be accessible to the subclass?

是的。 “and not with the subclass”只是“它不能被子类自动访问”——它并不是像明确禁止子类访问它一样。

见 Java Language Specification section 6.6详细信息。特别是:

Otherwise, we say there is default access, which is permitted only when the access occurs from within the package in which the type is declared.