Multiplicity defines how many objects participate in a relationship.
- Multiplicity is the number of instances of one class related to ONE instance of the other class
- For each association and aggregation, there are two multiplicity decisions to make: one for each end of the relationship
- Although associations and aggregations are bi-directional by default, it is often desirable to restrict navigation to one direction
- If navigation is restricted, an arrowhead is added to indicate the direction of the navigation
Step through the process of adding associations and association stereotypes to the use case diagram: