1. OOP Programming
Melick R. Baranasooriya
melick-rajee.blogspot.com

2. Principles of OOP
Abstraction Inheritance
Encapsulation Polymorphism
2

3. Inheritance
Staff
Member Gold
Loyalty
Non
Regular
Member
3

4. Classes and Interfaces
Classes Interfaces
methods and
Methods contain
Fields, properties, properties, left to
code for
methods be implemented 4
execution
later

5. 5

6. Inheritance
characteristics of existing Attributes
parent class Operations
extend the Add new
Redefine
parent fields and
methods
class methods 6

7. Extensibility
Inheritance
Reusability
inherits Provides
abstraction
Eliminates
implements Extends redundant
code 7

8. 8

9. Accessibility Levels
protected internal - limited Private -
to the current assembly or types derived from restricted to the
the containing class containing type
Protected - Public –
limited to the
Internal -
containing type and limited to the current access is not
assembly 9
types derived from it restricted

10. Important Aspects
Instance and static constructors No multiple
are not inherited inheritance
Multiple Transitive relation
Structures cannot
interfaces can be C < - B , B < -A
be inherited
implemented then C <-A 10

11. Demo
Virtual +
Sealed
Override
Multiple
Methods + New Access Modifiers
Interfaces 11

12. Abstraction – Reducing the
complexity
Classes defined with the Class +
keyword abstract Interface
Not implemented
Implemented or
methods are Cannot be
fully
declared instantiated
unimplemented 12
abstract

13. 13

14. Encapsulation
Hides the implementation Public
details interface
No interface
All data members Accessed via
members should
should be hidden properties
be hidden 14

15. Encapsulation ..
Constructors
Private data fields
and Assessors
Reduces
Changing the complexity
Change fields
class internals
validation Easier
does not affect 15
maintenance

16. Polymorphism Extensibility
Cohesion and Coupling
Reusability
Having many forms Provides
abstraction
Virtual Override Eliminates
Keyword Keyword redundant
code 16

17. 17

18. THANK YOU! 18