Relationships between two classes – Class Coupling in OOP

Class Relationships

• Class A inherits from Class B.
• Class A has an attribute of class B.



• Class A has a template attribute with a parameter of class B.
• Class A has a method with an argument of class B.
• Class A knows of a global variable of class B.
• Class A knows of a method containing a local variable of class B
• Class A is friend of Class B (in C++)

UML specifies the following six relationships between two classes:

1. Association
2. Aggregation
3. Composition
4. Inheritance
5. Dependency
6. Realization