Implementation of a Nested Interface of a Subclass

Question

In Java, can a class implement an interface nested in one of its sub-classes?

Could you provide an example of what are you trying to achieve? — default locale, Jan 15 '15 at 07:15
Thilo, it is not the sub-class that is implementing the interface; it is the super-class that is implementing the interface and the interface is in the sub-class. — Jack DeLano, Jan 15 '15 at 07:22
Are you asking if the superclass can already provide the implementation, so that the sub-class can just use it when it declares interface compliance? If so, yes. — Thilo, Jan 15 '15 at 07:23
" it is not the sub-class that is implementing the interface". Well, all subclasses inherit the interfaces from the superclass. So they cannot avoid also implementing it. — Thilo, Jan 15 '15 at 07:24
Ok, so a sub-class has an interface. My question is can the sub-class's super-class implement that interface? — Jack DeLano, Jan 15 '15 at 07:26

score 2 · Accepted Answer · answered Jan 15 '15 at 07:32

2

No, the compiler will find a cyclic inheritance. Just try it:

class C implements B.A {} 

class B extends C {
   interface A {}
} 
// won't compile

answered Jan 15 '15 at 07:32

PeterMmm

1 Answers1