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Tom Gustafsson

Joined: Aug 10, 2008
Posts: 6
Sierra & Bates Book for SCJP 5 training states that Has-a relationship always rely on instance variables.

With the book I got a CD with simulation of the exam + got one bonus exam for free.

In the bonus exam there was a question about Has-A relationship and "Has-a relationship always rely on instance variables." was one option which was not true. Explanation was that also classes static references are considered as HAS-A relationship.

That's confusing. What is the truth?
nadav ben hadar

Joined: Aug 10, 2008
Posts: 1
instance variables. and thats it....

some of the questions that you might find on the cd are also shown at the end of each chapter, such as this one which is question #1 on chapter 2.

the answer there is correct
marc weber

Joined: Aug 31, 2004
Posts: 11343

I would say that static variables do constitute a HAS-A relationship.

Note that HAS-A is typically contrasted with IS-A. That is, composition vs. inheritance. Whether a field is associated with the class or with an instance, it's still composition.

"We're kind of on the level of crossword puzzle writers... And no one ever goes to them and gives them an award." ~Joe Strummer
I agree. Here's the link:
subject: HAS-A
jQuery in Action, 3rd edition