TITLE: CLASS DIAGRAM
THEORY:
CLASS DIAGRAM
Class Diagram is a type
of Unified Modeling Language (UML) diagram. It describes the structure of a
system by showing the system’s classes, their attributes, operations and the
relationship among objects. It can be considered as the main building block of
Object-Oriented modeling.
Class diagram is
represented by a box with three compartments; these three compartments are
described as follows:
>The top compartment
contains the name of the class which is represented in bold and first letter is
capitalized.
>The middle
compartment contains the attributes of the class. They are left-aligned and
first letter is lowercase.
>The bottom
compartment contains the operations the class can excute.They are also
left-aligned and the first letter is lowercase.
The visibility of the attributes and the operations
can be reperesented in following ways:
Public:
A
public member is visible from anywhere in the system. In class diagram; it is
prefixed by the symbol ’+.’
Private: A
private member is visible only from within the class. It cannot be accessed
from outside the class. A private member is prefixed by the symbol ‘−’.
Protected:
A protected member is visible from within the class and from the subclasses
inherited from this class, but not from outside. It is prefixed by the symbol
‘#’.
In
the design of a system, a number of classes are identified and grouped together
in a class diagram that helps to determine the static relations between them.
With detailed modeling, the classes of the conceptual design are often split
into a number of subclasses.
Library
Management System
Figure:
Class Diagram for Library Management System
There are four classes in this class diagram of library
management systems which are Books, Librarian, Users, and Publisher. The
association between class Books, User, and Librarian is unary association and
relationship is one –to- many. Here librarian may or may not issue the books.
No one or many users can request up to 4 books. Librarian and user are in one
–to- many relationships and librarian can order books from one or many
publisher.
Order
Processing System
Figure:
Class Diagram for Order Processing System
There are four classes which are Customer, Order,
Product, and Store. The relationship among the class Customer and Order is one to
many that is a customer can place an order or many order. Oder class has a
number of products to be ordered and Store has a number of products to store,
i.e. one to many relationship.
Android Bluetooth Chat App
Figure:
Class Diagram for Android Bluetooth Chat App
From this lab session we got familiarized with the
class diagram. Class Diagram is the representation of class along with their
attributes and operation.
Hence, from this lab we understood about the class
diagram.
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