Dept. of CS & IT, Superior University
1
OO Relationships - Association,
Aggregation & Composition
[Note: Below material has been quoted from http://cs.joensuu.fi/pages/koles/oop/OOP_Development.ppt]
In Object Oriented world, if one class has to communicate with any other class (or classes), it has to
communicate by using one of the Object Oriented Relationships.
There are three (3) OO Relationships,
Inheritance or Generalization
Aggregation
o Weak
o Strong (Also called as Composition or Containment)
Association
Association
Association represents a general binary relationship that describes an activity between two classes.
An association is illustrated using a solid line between the two classes with an optional label that
describes the relationship.
Association may have navigability, i.e. direction of the relation. Each class involved in the relationship
may have a role name played by the class in the relationship.
Examples
A student taking a course is an association between the Student class and the Course class.
A faculty member teaching a course is an association between the Faculty class and the Course
class.
Figure: Class Diagram for Examples above
