Interface

[Sridhar Srinivasan]

Hi!
I read thro the K&B book and found a point regartding constructors.Interface doesn't have a constructor and they don't come under inheritance tree.Is it tru that they don't come under inheritance tree??
[ May 09, 2004: Message edited by: Barry Gaunt ]

[David Peterson]

Erm... yes and no.
Interfaces don't come under the class inheritance tree, but they can form their own interface inheritance tree.
i.e. an interface cannot extend a class, but interfaces can extend other interfaces.

[Sridhar Srinivasan]

ok Thanks.have one more doubt related to this.Suppose I have an object as return type in a method.In that case, any sub class can be returned.If the object returned is an interface, can a class which implements the interface is legal return type or not?

[Jeroen Wenting]

yes it can. An Object that implements an interface is considered to be part of the inheritance tree of that interface as well as that of its superclass.
As you can return any subclass or subinterface of the declared one from a method that means you can return an implementing class.
If such weren't possible the miriad methods returning Lists, Maps, etc. etc. would all be impossible.