Enthuware

Re: the note about aggregation and the statement that D is a member object in A. Class C creates an instance of D, not A. So I'm confused as to why it can be said that A 'has-a' D.

The statement is about the code shown at the top of the explanation and not about the code in the question.
I agree that different names for the classes in the explanation would avoid this confusion.

HTH,
Paul.

Thank you ... I missed that when I was reviewing answers.

Yes, it is needed to change class names for the code snippet in the explanation. I was the next to be confused.

I have another question. It is stated that "Aggregation defines a has-a relation.". However, Finegan/Liguori OCAJP study guide states that "direct association" stands for "has-a" and "aggregation association" stands for "is part of". Looks like they're kinda wrong.

The question presents the following code:

interface X1{ }
interface X2{ }
class A { }
class B extends A implements X1{ }
class C extends B implements X2{
D d = new D();
}
class D { }

It is strange that one of the correct answers is:
C is-a A
While we all aware to the fact that inheritance works only for the 2nd generation, means only
for the class that extends it???

Nisim123 wrote: While we all aware to the fact that inheritance works only for the 2nd generation, means only
for the class that extends it???

That is not correct. Where did you read that?
Paul.

I think, but still not sure, that it was the explanation to one of the questions about inheritance
of Enthuware Test Studios,
or that i read it in the Kathy Sierra & Bert Bates guide in chapter 2, but if you say that it is not correct, then I will accept it as is. It might be that it is true only about the implemented interfaces or something I should certainly check that out.
yours,
nisim.

Well I probably was confused with calls to a constructor that can be only one class up...