Class Diagrams ll

Question 1

What is aggregation?

Answer 1

Type of association used to express that a class is part of another class

Question 2

Transitive aggregation

Answer 2

An aggregation relationship that can be chained through multiple levels

Question 3

Transitive aggregation example

Answer 3

If B is part of A and C is part of B, C is also part of A

Question 4

Asymmetric aggregation

Answer 4

An aggregation relationship that is not bidirectional

Question 5

Asymmetric aggregation example

Answer 5

It is not possible for A to be part of B and B to be part of A simultaneously

Question 6

Shared aggregation

Answer 6

A relationship between classes where one class aggregates multiple instances of another class which can be shared among multiple classes

Question 7

Shared aggregation syntax

Answer 7

Hollow diamond at the aggregating end

Question 8

Composition

Answer 8

A relationship between two classes where one class is composed of one or more instances of another class

Question 9

Composition syntax

Answer 9

Solid diamond at the aggregating end

Question 10

Generalisation

Answer 10

A hierarchical relationship where a sub/child class inherits attributes and behaviours from a super/parent class

Question 11

Abstract class

Answer 11

A class that cannot be instantiated on its own and is designed to serve as a blueprint for other classes

Question 12

Multiple inheritance

Answer 12

Allows a subclass to inherit characteristics and behaviours from more than one superclass

Question 13

Class

Answer 13

Description of the structure and behaviour of a set of objects