Relationship #

There are three kinds of relationships in the UML Class diagram:

• dependencies
• associations
• generalizations

We use a line (connector) to show a relationship. Different relationships are depicted differently (e.g. dashed vs solid line, arrow vs diamond head, etc.); so, pay attention to the depiction of relationships in the examples that follow.

Dependency Relationships #

A dependency shows a class (somehow) uses the other one.

The dependency from Schedule to Course exists because Course is used in the add operation of Schedule.

A dependency may also indicate a semantic relationship between two classes.