1. By:
Altaf Hussain
SS KRL
BS(CS), AU Peshawar, MS(CSE), NUST Islamabad

2.  Understand the basic principles of object orientation
 Understand the basic concepts and terms of object

3.  Basic Principles of Object Orientation
 Basic Concepts of Object Orientation

4. Object Orientation
Encapsulation
Abstraction
Hierarchy
Modularity

5. 5
 Abstraction allows us to manage complexity by
concentrating on essential aspects making an entity
different from others.
 A process allowing to focus on most important aspects
while ignoring less important details.

6. Salesperson
Not saying Which
salesperson – just
a salesperson in
general!!!
Customer
Product
Manages Complexity

7.  Hide implementation from clients
• Clients depend on interface
How does an object encapsulate?
What does it encapsulate?

8.  The breaking up of something complex into
manageable pieces
Order Processing
System
Order Entry
Order Fulfillment
Billing

9. Decreasing
abstraction
Increasing
abstraction
Asset
RealEstate
Savings
BankAccount
Checking Stock
Security
Bond
Elements at the same level of the hierarchy
should be at the same level of abstraction
 Levels of abstraction – ordering of abstraction in a tree
like structure

10.  Basic Principles of Object Orientation
 Basic Concepts of Object Orientation

11.  Object
 Class
 Attribute
 Operation
 Interface
 Implementation
 Association
 Aggregation
 Composition
 Generalization
 Super-Class
 Sub-Class
 Abstract Class
 Concrete Class
 Discriminator
 Polymorphism

12. Truck
Chemical Process
Linked List
 Informally, an object represents an entity, either
physical, conceptual, or software
• Physical entity
• Conceptual entity
• Software entity

13.  An object is a concept, abstraction, or thing with sharp
boundaries and meaning for an application
 An object is something that has:
• State
• Behavior
• Identity

14. 14
 Object-oriented programming supports the view that
programs are composed of objects that interact with
one another.
 How would you describe an object?
 Using its characteristics (has a ----?) and its behaviors
(can do ----?)
 Object must have unique identity (name) : Basketball,
Blue ball
 Consider a ball:
• Color and diameter are characteristics (Data
Declarations)
• throw, bounce, roll are behaviors (Methods)

15. 15
 A class defines the general nature of a collection of
objects of the same type.
 The process creating an object from a class is called
instantiation.
 Every object is an instance of a particular class.
 There can be many instances of objects from the same
class possible with different values for data.

16. Objects Example
16
class Rose
blueRose
redRose
class
objects
Object
References

17. OO Principle: Abstraction
 A class is a description of a group of objects with
common properties (attributes), behavior (operations),
relationships, and semantics
• An object is an instance of a class
 A class is an abstraction in that it:
• Emphasizes relevant characteristics
• Suppresses other characteristics

18. a + b = 10
Class
Course
Properties
Name
Location
Days offered
Credit hours
Start time
End time
Behavior
Add a student
Delete a student
Get course roster
Determine if it is full

19. Professor
name
empID
create( )
save( )
delete( )
change( )
Class Name
Attributes
Operations
 A class is comprised of three sections
• The first section contains the class name
• The second section shows the structure (attributes)
• The third section shows the behavior (operations)

20.  How many classes do you see?

21. Objects Class
Professor Smith
Professor Jones
Professor Mellon
Professor
 A class is an abstract definition of an object
• It defines the structure and behavior of each object in the class
• It serves as a template for creating objects
 Objects are grouped into classes

22. :CourseOffering
number = 101
startTime = 900
endTime = 1100
:CourseOffering
number = 104
startTime = 1300
endTime = 1500
CourseOffering
number
startTime
endTime
Class
Attribute
Object
Attribute Value

23. CourseOffering
addStudent
deleteStudent
getStartTime
getEndTime
Class
Operation

24. 24
 A class that lacks a complete implementation and
provides operations without implementing some methods
 Cannot be used to create objects; cannot be instantiated
 A concrete sub-class must provide methods for
unimplemented operations

25. 25
 Has methods for all operations
 Can be instantiated
 Methods may be:
a) defined in the class or
b) inherited from a super-class

26. 26
 Discriminator – an attribute that defines sub-classes
 Example: “status” of company staff is a possible
discriminator to derive “management”, “senior” and
“junior” sub-classes.

27. 27
 Ability to dynamically choose the method for an
operation at run-time or service-time
 facilitated by encapsulation and generalization:
• encapsulation – separation of interface from
implementation
• generalization –organizing information such that
the shared features reside in one class and
unique features in another
 Operations could be defined and implemented in the
super-class, but re-implemented methods are in unique
sub-classes.

28. Manufacturer A
Manufacturer B
Manufacturer C
OO Principle:
Encapsulation
 The ability to hide many different implementations
behind a single interface

29. Tube
Pyramid
Cube
Shape
Draw
Move
Scale
Rotate
<<interface>>
Realization relationship (stay tuned for realization relationships)
 Interfaces formalize polymorphism
 Interfaces support “plug-and-play” architectures

30.  Association
• Aggregation
• Composition
 Dependency
 Generalization
 Realization

31. Professor UniversityWorks for
Class
Association
Association Name
Professor University
EmployerEmployee
Role Names
 Models a semantic connection among classes

32. Student Schedule
Whole
Aggregation
Part
 A special form of association that models a whole-part
relationship between an aggregate (the whole) and its
parts

33. Student Schedule
Whole
Aggregation
Part
 A form of aggregation with strong ownership and
coincident lifetimes
• The parts cannot survive the whole/aggregate a

34.  Multiplicity defines how many objects participate in a
relationships
• The number of instances of one class related to ONE
instance of the other class
• Specified for each end of the association
 Associations and aggregations are bi-directional by
default, but it is often desirable to restrict navigation to
one direction
• If navigation is restricted, an arrowhead is added to
indicate the direction of the navigation

35. Student Schedule1 0..*
Multiplicity
Navigation

36. Client Supplier
Package
ClientPackage SupplierPackage
Client Supplier
Class
Dependency
relationship
Dependency
relationship
Component
 A relationship between two model elements where a
change in one may cause a change in the other
 Non-structural,“using” relationship

37.  A relationship among classes where one class shares
the structure and/or behavior of one or more classes
 Defines a hierarchy of abstractions in which a subclass
inherits from one or more super-classes
• Single inheritance
• Multiple inheritance
 Generalization is an “is-a-kind of” relationship

38. Account
balance
name
number
Withdraw()
CreateStatement()
Checking
Withdraw()
Savings
GetInterest()
Withdraw()
Superclass
(parent)
Subclasses
Generalization
Relationship
Ancestor
Descendents
 One class inherits from another

39. Airplane Helicopter Wolf Horse
FlyingThing Animal
Bird
multiple
inheritance
Use multiple inheritance only when needed, and
always with caution !
 A class can inherit from several other classes

40. Inheritance leverages the similarities among classes
 A subclass inherits its parent’s attributes,
operations, and relationships
 A subclass may:
• Add additional attributes, operations, relationships
• Redefine inherited operations (use caution!)
 Common attributes, operations, and/or
relationships are shown at the highest
applicable level in the hierarchy

41. Truck
tonnage
GroundVehicle
weight
licenseNumber
Car
owner
register( )
getTax( )
Person
0..*
Trailer
1
Superclass
(parent)
Subclass
generalization
size

42. Component
Interface
Use Case Use-Case Realization
Elided form
Class
Interface
Subsystem
Interface
Canonical form
 One classifier serves as the contract that the other classifier
agrees to carry out
 Found between:
• Interfaces and the classifiers that realize them
• Use cases and the collaborations that realize them