Hci Paper

Software Engineering I

Class Diagram

Elements of the Class Diagram

1. Class

•

The class is the basic component of the class diagram where each class has a class

name, a set of attributes (optional), and a set of methods (optional). Also the scope

of the attributes and methods should be shown for each class (Private, Package,

Protected, Public).

class System

Employee

-

id: int

name: char

+ getID() : int

+ getName() : char

+ setID(int) : void

+ setName(char) : void

1

2. Association Relationship:

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The association relationship describes a relationship between two classes where one

class can use another class in some way (or it can be a reflexive relationship for one

class) where both classes have their own life cycles and are independent of each

other. Also note that the multiplicity properties of the classes must be specified and

that it must be indicated whether it is a bidirectional (having zero or two

arrowheads) or unidirectional relationship (having one arrow head). This type of

relationship can optionally be assigned a meaningful name to describe how the two

classes are associated.

•

Association Class:

An association class is used whenever there is a need for an association relationship

to have attributes and methods that are part of the relationship between the two

associated classes.

class System

Professor

Course

Teaches

1

1..*

3. Aggregation Relationship:

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The aggregation relationship describes a relationship between two classes where one

class is said to belong to another class. This type of relationship is said to be a “HASA” relationship where the owner class owns the owned class but the life time of the

owned class is independent of the owner class.

class System

MusicPlayer

Car

1

1

2

4. Composition Relationship:

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The composition relationship describes a relationship between two classes where

one class is said to belong to another class. This type of relationship is said to be a

“WHOLE-PART” relationship where the owner class owns...