NOTE
Class Diagram
What a class diagram is, how classes/interfaces and common class relationships are represented, with PlantUML examples.
This is a historical learning note and may contain outdated or incomplete understanding.
1. What Is It?
Describes the attributes and methods of Classes in a system, as well as the relationships between Classes.
2. Usage
2.1. Classes and Interfaces
- means public
- means private
2.2. Relationships Between Classes
2.2.1. Generalization and Realization
Symbol: triangle.
Generalization means extending a class. Solid line.
Realization means implementing an interface. Dashed line.
2.2.2. Aggregation and Composition
Symbol: diamond.
They emphasize the relationship between the whole and the part.
Aggregation refers to strong dependency, depending on another class as an attribute. Filled diamond.
Composition refers to weak dependency, depending on another class as an attribute. Hollow diamond.
2.2.3. Association and Dependency in UML
Symbol: arrow.
Association means using another class as an attribute. Solid line.
Dependency means using another class as a method parameter. Dashed line.
3. Example
Discussion
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