Difference between aggregation relationship and the composition relationship?

If anyone could please explain to me in a simple way the difference between aggregation relationship and composition relationship....i am lost on this...please help
To start with, have you checked out the relevant Wikipedia article(s)?

From http://en.wikipedia.org/wiki/Object_composition


Aggregation differs from ordinary composition in that it does not imply ownership. In composition, when the owning object is destroyed, so are the contained objects. In aggregation, this is not necessarily true. For example, a university owns various departments (e.g., chemistry), and each department has a number of professors. If the university closes, the departments will no longer exist, but the professors in those departments will continue to exist. Therefore, a University can be seen as a composition of departments, whereas departments have an aggregation of professors. In addition, a Professor could work in more than one department, but a department could not be part of more than one university.

As this states, the difference relates to object ownership and lifetime.
Last edited on
Topic archived. No new replies allowed.