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
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
    • Abstraction
    • Substitution
    • Usage
  • 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.
  • A filled diamond (or black diamond) with a solid line represents an composition.
  • An empty diamond (or white diamond) with a solid line represents a aggreation.

Draw Arrows, Connectors and Other Parts of UML Diagrams using UML Tool

You can create UML diagrams with the mentioned relationships using the UML tool Software Ideas Modeler. You can download it here:

Comments

Blackburn 6 January 2021 0:25:13

Discrepency between text and image

The solid diamond and hollow diamond are transposed between the image and the accompanying text.

Dusan Rodina - softwareideas.net 6 January 2021 16:59:12

RE: Discrepency between text and image

Thank you for your notice. It's fixed now.

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