Talking about UML concept and model UML class diagram relationship

content

1. UML view
2. UML diagrams
3. UML class diagram relationship

There are usually four types of relationships between classes, namely Dependency, Generalization, Association, and Realization
1. Dependency
[Concept] means two The semantic connection relationship between or between multiple model elements
[Drawing method] Dotted arrow, the arrow points to the user
[Dependency diagram]

2. Generalization relationship (inheritance) (Generalization)
[Concept] Describe the general and specific relationship of a class The relationship of "is a kind of" described
[Drawing method] Solid hollow triangle arrow, the arrow points to the parent class
[Inheritance method]

1. 单继承
一个类只有一个父类
2.多继承
一个类可以有多个父类，可以从每一个父类中获得允许继承的信息
【泛化图】

3. Association
[Concept] Represents the semantic connection between the object of one thing and the object of another thing, which is simply understood as a strong dependency between two classes or a class and an interface
[Drawing method] Realization Line arrow, double arrow or no arrow
[included]

1.聚集
【概念】描述的是部分与整体关系，描述了“has a”的关系，部分离开整体可以单独存在
【绘图方式】空菱形的实线，头部指向整体
【聚集关系图】

2.组成
【概念】一种更强形式的关联，在整体中拥有管理部分特有的职责，也被称为强聚合关系，部分不能脱离整体存在
【绘图方式】实菱形的实线，头部指向整体
【组成关系图】

4. Realization
[Concept] Connect a model relationship with another model relationship, so as to explain the relationship with its implementation, which is simply understood as one class or multiple classes implement an interface
[drawing method] ] The dotted line enclosing the empty arrow, the arrow points to the interface
[Implementation relationship diagram]

The difference between generalization and implementation relationship: the
generalization relationship refers to the connection of elements in the same semantic layer, usually in the same model; the implementation relationship connects the elements in different semantic layers Elements are connected, usually within different models.