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INTRODUCTION TO OBJECT-
ORIENTED PROGRAMMING
(OOP)
1

OOP CONCEPT
 Enable programmers to create modules that do not
need to be changed when a new type of object is
added.
 Programmer can simply create a new object that
inherits many of its features from existing objects
 Makes object-oriented programs easier to modify
2

HISTORY OF OOP
 Many people believe that OOP is a product of the
1980s (Bjarne Stroustrup).
 Actually, SIMULA 1 (1962) and Simula 67 (1967)
[earliest object-oriented languages]
 The work on the Simula languages (Ole-John Dahl
and Kristen Nygaard) at the Norwegian Computing
Center in Oslo, Norway.
 Most of the advantages of OOP available in the
earlier Simula languages, it wasn't until C++
became entrenched in the 1990s that OOP began
to flourish.
3

ADVANTAGES OF USING OOP
 OOP provides a clear modular structure for
programs which makes it good for
defining abstract data types where implementation
details are hidden and the unit has a clearly defined
interface.
 OOP makes it easy to maintain and modify existing
code as new objects can be created with small
differences to existing ones.
 OOP provides a good framework for code libraries
where supplied software components can be easily
adapted and modified by the programmer.
4

TERMINOLOGIES OF OOP
 Classes
 Object
 Encapsulation
 Data Abstraction
 Inheritance
 Polymorphism
5

CLASSES
 A collection of objects of a similar type.
 Once a class is defined, any number of objects can
be created which belong to that class.
 A class is a blueprint, or prototype, that defines the
variables and the methods common to all objects of
a certain kind.
6

OBJECT
 An instance of a class.
 A class must be instantiated into an object before it
can be used in the software.
 A software bundle of related state and behavior.
 More than one instance of the same class can be in
existence at any one time.
7

ENCAPSULATION
 Storing data and functions in a single unit
(class).
 Mechanism that binds together code and
data in manipulates.
 Keeps both safe from outside interference
and misuse.
 Data cannot be accessible to the outside
world and only those functions which are
stored in the class can access it.
8

DATA ABSTRACTION
 Abstraction refers to the act of representing
essential features without including the background
details or explanations.
 Classes use the concept of abstraction and are
defined as a list of abstract attributes.
9

INHERITANCE
 Provides a powerful and natural mechanism for
organizing and structuring your software.
 This section explains how classes inherit state and
behavior from their superclasses, and explains how
to derive one class from another using the simple
syntax provided by the Java programming
language.
10

POLYMORPHISM
 The ability to take more than one form.
 An operation may exhibit different behaviors in
different instances.
 The behavior depends on the data types used in
the operation.
 In general, polymorphism means “one interface,
multiple method”
 Reduce complexity by allowing the same
interface to be used to specify a general class of
action.
11

DISTINGUISH BETWEEN ABSTRACTION AND
ENCAPSULATION
ABSTRACTION ENCAPSULATION
Refers to showing only the
necessary details to the intended
user
Means to hide (data hiding).
Wrapping, just hiding
properties and methods.
Used in programming languages
to make abstract class.
Used for hide the code and
data in a single unit to protect
the data from the outside the
world.
Abstraction is implemented using
interface and abstract class
Encapsulation is
implemented using private
and protected access
modifier. 12

EXAMPLES
ABSTRACTION
ENCAPSULATION
Class Encapsulation
{
private int marks;
public int Marks
{
get { return marks; }
set { marks = value;}
}
}
abstract class Abstraction
{
public abstract void
doAbstraction();
}
public class AbstractionImpl:
Abstraction
{
public void doAbstraction()
{
//Implement it
}
}
13

DIFFERENCES
Structured Programming OOP
Follow top-down approach to
program design.
Follow bottom-up approach in
program design.
Data and Functions don’t tide with
each other.
Functions and data are tide
together.
Large programs are divided into
smaller self contained program
segment known as functions.
Programs are divided into entity
called Objects.
Data moves openly around the
system from function to function.
Data is hidden and can’t be
accessed by the external world
Functions are dependent so
reusability is not possible
Functions are not dependent so
reusability is possible 14

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