UML Arrows - Know UML Relationship Types
UML diagrams use different types of arrows. Each arrow type represents another relationship. Sometimes the relationships are depicted in the same way, but they have a slightly different meaning. In that case, they can be annotated with a stereotype.
UML Class Diagram Arrows and Relationships
Different arrows have different meanings in class diagrams. They represent various types of relationships.
UML class diagram arrows
Class diagrams use these UML arrows:
- A triangle-head arrow with a solid line represents a generalization.
- A triangle-head arrow with a dashed line represents a realization.
- A circle with a plus sign represents a containment.
- An arrow with a dashed line is used for dependencies. Except for a general dependency it may be further specialized as
- A solid line without any decoration represents an association.
- An arrow with a solid line represents a directional association.
- A double-arrowed line is used for bidirectional association.
- An empty diamond (or white diamond) with a solid line represents a composition.
- A filled diamond (or black diamond) with a solid line represents an aggreation.