The document discusses class diagrams and their components. A class diagram visually represents the structure of a system by showing classes, their attributes, operations or methods, and the relationships between classes. It includes boxes to represent classes with three parts - name, attributes, and operations. It also discusses the different types of relationships between classes including generalization, association, aggregation and composition.

1. Start with the Name of
ALLAH(j)
Who is most Gracious and Merciful

2. Name: Sayed Farhan Ali Shah
Roll No: 39
Subject: Introduction to Software Development
Department: I.T Computer Science
Institute: Shah Adbul Latif University Khairpur Sindh
Pakistan

4. Class Diagram
 Used for describing structure and behavior
in the use cases
 Provide a conceptual model of the system in
terms of entities and their relationships

5. Class is represented with boxes
which contain three parts:
Name
Attributes
Operations

6. NAME
The top part contains the name of the class. It is
printed in Bold, centered and the first letter
capitalized.
ATTRIBUTES
The middle part contains the attributes of the class.
They are left aligned and the first letter is lower case.
OPERATIONS
The bottom part gives the methods or operations the
class can take or undertake. They are also left
aligned and the first letter is lower case.

7. Modifiers are used to indicate
visibility of attributes and operations.
‘+’ is used to denote Public visibility (everyone)
‘#’ is used to denote Protected visibility (friends and
derived)
‘-’ is used to denote Private visibility (no one)
 By default, attributes are hidden and operations
are visible.
 The last two compartments may be omitted to
simplify the class diagrams

8. An example of Class
Account_Name
- Customer Name
- Balance
+add Funds( )
+with Draw( )
+transfer( )
Name
Attributes
Operations

9. There are two kinds of Relationships
 Generalization (parent-child relationship)
 Association (student enrolls in course)
Associations can be further classified as
 Aggregation
 Composition

10. Generalization
 Generalization expresses a parent/child
relationship among related classes.
 Used for abstracting details in several layers
Super type
Subtype1 Subtype2
Example

11. Association
Associations represent relationships between instances
of classes .
An association is a link connecting two classes.
Bi-directional association
Associations are assumed to be bi-directional
e.g. Flight and plane
notation:
Uni-directional association
e.g. Order and item
notation:

12. Composition
 Composition: expresses a relationship among
instances
of related classes. It is a specific kind of Whole-Part
relationship
 It expresses a relationship where an instance of the
Whole-class has the responsibility to create and initialize
instances of each Part-class.

13. 1 2
Automobile
Engine Transmission
Example of Composition
Person
Legs Hands

14. Aggregation
 Aggregation: expresses a relationship among
instances of related classes. It is a specific kind of
Container Containee relationship.
 It expresses a relationship where an instance of the
Container-class has the responsibility to hold and
maintain instances of each Containee-class that have
been created
outside the auspices of the Container-class.

15. Example of Aggregation
Bag
Books Apples

16. Thank
You