UML Class Diagram

The class diagram is a static diagram. It represents the static view of an application. Class diagram is not only used for visualizing, describing and documenting different aspects of a system but also for constructing executable code of the software application.

The class diagram describes the attributes and operations of a class and also the constraints imposed on the system. The class diagrams are widely used in the modelling of object oriented systems because they are the only UML diagrams which can be mapped directly with object oriented languages.

The class diagram shows a collection of classes, interfaces, associations, collaborations and constraints. It is also known as a structural diagram.

OBJECT

An object is an instance of a class.

ATTRIBUTES

Details of a class(the color of a car, the number of sides in a shape, etc.) are represented as attributes.

Attribute using relationship notation

Relationship notation using constraints

Derived Attributes

The derived notation, which is the leading forward slash(/), can be used as an indicator to the implementer that the attribute may not be strictly neccesary.

Attribute Multiplicity

The multiplicity of an attribute specifies hoe many instances of the attribute’s type are created when the owing class is instantiated.