Chap1 Oops

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Chapter-1

Object Oriented Programming Presented by Anurag Kumar
http://www.anuragkumar.co.nr/http://www.anuragkumar.co.nr/


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Process Oriented Model Programs are written around What is happening i.e.

emphasis is on the procedure.

Procedural Languagesuch as C Languagefollows this

model.


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Object Oriented Model Programs are written around Who is being affectedi.e.

emphasis is on data rather than the procedure.

Object Oreinted Languagessuch as Java, C++,

Smalltalk, Ada, ObjectPascalfollows this model.


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Whats an Object An object is a software bundle of variables and related

methods.

These variables and methods are formally known as

instance variables and instance methods.



Whats a Class A class is a blueprint or prototype that defines the

variables and methods common to all objects of acertain kind.



Messages Software objects interact and communicate with each

other by sending messages to each other. When objectA wants object B to perform one of B's methods, object

A sends a message to object B.



What makes a MessageThree components comprise a message:

1. The object to whom the message is addressed

2. The name of the method to perform

3. Any parameters needed by the method



The Benefits of Messages An object's behavior is expressed through its methods,

so (aside from direct variable access) message passingsupports all possible interactions between objects.

Objects don't need to be in the same process or even onthe same machine to send and receive messages backand forth to each other.



The Three OOP Principles1. Encapsulation

2. Inheritance

3. Polymorphism



1. Encapsulation As you can see from the diagrams, the object's variables

make up the center or nucleus of the object. Methodssurround and hide the object's nucleus from other

objects in the program. Packaging an object's variableswithin the protective custody of its methods is calledencapsulation.



Benefits of Encapsulation Modularity--The source code for an object can be

written and maintained independently of the sourcecode for other objects. Also, an object can be easily

passed around in the system.

Information hiding--An object has a public interfacethat other objects can use to communicate with it. Butthe object can maintain private information and methods

that can be changed at any time without affecting theother objects that depend on it.


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2. Inheritance Inheritance is the process by which objects of one

class acquire the properties of objects of anotherclass.


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The Benefits of Inheritance Reusability:Subclasses provide specialized behaviors

from the basis of common elements provided by thesuperclass. Through the use of inheritance,

programmers can reuse the code in the superclassmany times.


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3. Polymorphism Polymorphism means the ability to take more than one

form.

Its a feature that allows one interface to be used for a

general class of actions

Shape

draw()

Circle

draw()

Rect

draw()

Triangle

draw()


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Benefits of OOPS Through inheritance, we can eliminate redundant

code and extend the use of existing classes.

The principle of data hiding helps the programmer to

build secure programs that cannot be invaded bycode in other parts of the program.

It is possible to map objects in the problem domainto the objects in the program domain.

Object oriented systems can be easily upgradedfrom small to large systems.

Software complexity can be easily managed.


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Applications of OOP Real-time Systems

Simulation & Modelling

Object Oriented Databases

Expert Systems

Neural Networks and Parallel Programming

Decision Support and Office Automation Systems

CAD/CAM Systems


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AssignmentsQ.1 What is Object-Oriented Programming? How is it

different from the Procedure-Oriented (Procedural)Programming?

Q.2 Distinguish between the following terms:a) Objects and Classes

b) Data Abstraction and Data Encapsulation

c) Inheritance and Polymorphism

d) Dynamic Binding and Message Passing

anuraggie-java@yahoo co in

anuraggie-java@yahoo co in


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End of Chapter-1 Thank You

Chap1 Oops

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