Four kinds of relationships in UML

four common types of UML relationships:

Generalized relationships, association relationships, implementation relationships, dependency relationships

The generalization relation refers to the inheritance relationship between the parent class and the subclass.

The realization relation refers to the relationship between the interface and the implementation class;

The difference between dependency and association is as follows:

As long as there is interaction between objects, whether controlled or data, there is a dependency between the two. We are now talking about dependence, which is a weaker relationship than association.

Dependency is a transient relationship between objects, in which the called class behaves as a local variable of the calling class, a parameter to the method, and a static method that invokes the called class, in which case we say that the calling class and the called class are dependent.

Association is a long-term relationship between objects, in which the called class behaves as a reference to the calling class, or a property of the calling class, in which case we say that the calling class and the called Class belong to the association relationship.

Common relationships are: one-to-many relationships, multiple relationships, many-to-many relationships, such as a typical customer-to-order, company-to-employee relationship is an association relationship

Four kinds of relationships in UML