1. OBJECT ORIENTED PROGRAMMING overview
Chapter 1

2. Introduction
Aims:
to establish understanding of basic concepts of Object Oriented Programming (OOP)
What will be covered:
Procedural Programming vs OOP
History of OOP
Object Oriented Application
basic concept of OOP

3. Introduction
There are two most widely used programming language styles:
Procedural Programming
Object Oriented Programming

4. Procedural Vs Object Oriented Programming
Procedural programming
also known as structural programming languages
This type of style allows programmers to write program according to a set of steps for solving problems, usually in a top down manner and in chronological order.
It relies on functional decomposition which means the system is broken down into components/ functions/ procedures.
The programming relies heavily on the 3 basic structures: sequence, selection and iteration.
using traditional programming languages e.g. C, Fortran, Cobol etc.

5. Procedural Vs Object Oriented Programming
The world around us are made up of objects e.g. people, cars, trees, buildings etc
This is used to model a software system as a set of objects interacted with each other.
The Objects represent the system components
Each OO program file must contain at least one class
Some of the programming language used are Java, C++, C#, VB.NET etc.

6. planning the application
Procedural Vs Object Oriented Programming
Object-Oriented Programming is VERY different from procedural programming.   Instead of think of "steps/processes" to solving a problem, we need to think about and identify the objects involved in the problem and how they'll interact. Each object is responsible for its own activities and data.
OO developer however must still follow the step of understanding the problem and
planning the application

7. Procedural Vs Object Oriented Programming
APPLICATION
PROCEDURAL
APPLICATION
Class file:
variables
methods
Data
Data
Application file:
Input
Output
Object creation
Class file:
variables
methods
Application file:
Variables
Methods
Input
Output
Class file:
variables
methods

8. Procedural Vs Object Oriented Programming
The previous diagrams shows that
In procedural programming,
all input, output, variables and methods are put in a single file.
This is quite large and difficult to maintain
In Object Oriented Programming,
most variables and methods are organized within separate classes that define different kind of objects.
A separate, smaller application file handles input and output and creates the needed objects.
OO approach produces more modular and organized application

9. Architecture - Java OO program file e.g. calculateSalary.java Class/es
Method/s
e.g. (main)
Statements
e.g. System.out.println(“Please enter hours worked”)

10. Object Oriented Approach
Object oriented approach intended to produce systems which are composite, modular constructions, build using abstraction, and organized around the data.
Suitable to solve large and evolving software system.
Most research claimed that OO IS is much easier to maintain compared to the traditional IS.

11. History of OOP
Object programming was reported to exists in Simula 67 back in 1960s
Simula 67 is developed at the Norwegian Computing Center in Oslo, by Ole-Johan Dahl and Kristen Nygaard.
Simula 67 is used to program Simulation
Influenced from Simula 67, later, the theory of OOP is introduced by smallTalk (Xerox PARC) which further designed it to include the pervasive use of objects and messages as the basis for computation.
Mid 1980s, OOP dominant the programming methodology through C++ (an extension of C Language)
More recently, a number of OOP languages exists such as Visual Basic .NET, C#

12. Object Oriented Programming
Why is Object Oriented introduced?
Object Oriented Programming is introduced because of the limitation of the procedural programming which are:
programs written in procedural language become complex very quickly (1000s lines of code) if very large system is developed
difficult to test and maintain
often re-implement code unnecessarily (a large system is normally programmed by more than 1 developer

13. Object Oriented Programming
Object-Oriented programming uses 3 main concepts:
Inheritance – copying the attributes and methods from the base/parent classes
Encapsulation – data hiding (hiding the attributes from the outside world)
Polymorphism – using methods of the same name for a variety of purposes (overriding or overloading)

14. Object Oriented Terms and Concepts
An object simply represents any object that you may think of in the "real world".
Tangible (like real objects that you can touch):
e.g., a House, a Car, a Person, etc...
Non tangible objects (sometimes harder to identify):
e.g., a BankAccount, Insurance, a Loan, a Vacation, etc...

15. Object Oriented Terms and Concepts
Objects are made up of two "things":
state (a.k.a. attributes/fields/properties + value)
A given set of data which describes the object
e.g., colour, size, amount, name, phoneNumber, etc...
behaviour (a.k.a. methods or functions)
A set of operation that the object can perform
e.g., walk, run, drive, sell, buy, transfer, computeTotal, open, close, etc...

16. Object Oriented Terms and Concepts
Example of Object, state, behaviour
Object
State
Behaviour
Person
name, age, gender, phone number
get the address, change phone number
Customer
name, address,
purchase history
make purchase, list items bought, return item
BankAccount
owner, balance, accountnumber
withdraw, deposit, transfer, get balance

17. Object Oriented Terms and Concepts
An object is a specific item in the class, often referred to an instance/example of a class.
A class is simply a template/mould/blueprint for constructing objects of a specific type.
Before you can use an object in your program, you MUST define the class.   In fact, ALL objects MUST belong to a class of some kind.

18. Object Oriented Terms and Concepts
Class : Fruit
Instances of fruit
An instance of the Fruit class refers to a specific fruit.
These are all objects

19. Construction of OO Programming
So how do we actually write an Object-Oriented program ?
Identify  the Objects (i.e., Classes) that represent our problem which is to be solved (or simulated)
identify the object characteristics (i.e., state and behaviour)
Identify the inter-relationships between the Objects (i.e., how they interact).

20. Example Scheduling application Involves objects such as:
Students
Course
Schedule
Objects attributes
Student – ID, name, gender, dob
Course – dept, number, descr, credit hrs
Schedule – semester, studentID, a number of courses
Object behaviour
Schedule – assign studentID and course

21. Exercise
Identify 3 objects that might belongs to each of the following classes:
automobile
animal
bankAccount
footballPlayer
mobilePhone