A class diagram is a type of static structure diagram in the Unified Modeling Language (UML) used in software engineering to describe the structure of a system by showing the systems classes, their attributes, operations (or methods), and the relationships among objects. It is used to visualize, describe, and document various aspects of a system, and also to construct executable software code.
A UML class diagram is made up of:
- A description of a group of objects all with similar roles in the system
- A class notation consisting of three parts: the graphical representation of the class, a list of the classs attributes, and a list of the classs operations
- Relationships between classes, which can be one of the following types: inheritance (or generalization), simple association, or aggregation
Class diagrams are widely used in the modeling of object-oriented systems because they are the only UML diagrams that can be mapped directly with object-oriented languages. They are used in different development phases of a software development lifecycle and typically by modeling class diagrams in three different perspectives (levels of detail) progressively as we move forward.
In summary, a class diagram is a graphical representation of the static view of a system that shows the classes, attributes, operations, and relationships between objects in a system. It is used to model the structure of a system and to construct executable software code.
