What do relationships enable objects to do? What is the strongest kind of relationship? Walk through an example that demonstrates your understanding of the concept.

Question

What will be an ideal response?

Answer 1

Relationships enable objects to communicate and interact as they perform business functions and transactions required by the system. Relationships describe what objects need to know about each other, how objects respond to changes in other objects, and the effects of membership in classes, superclasses, and subclasses. Some relationships are stronger than others (just as a relationship between family members is stronger than one between casual acquaintances). The strongest relationship is called inheritance. Inheritance enables an object, called a child, to derive one or more of its attributes from another object, called a parent. As one example, the INSTRUCTOR object (child) inherits many traits from the EMPLOYEE object (parent), including SOCIAL SECURITY NUMBER, TELEPHONE NUMBER, and HIRE DATE. The INSTRUCTOR object also can possess additional attributes, such as TYPE OF INSTRUCTOR. Because all employees share certain attributes, those attributes are assumed through inheritance and do not need to be repeated in the INSTRUCTOR object.