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CONTENT
2
1. Inroduction to OOP��s
2. The Need Of OOP
3. Component Of OOP
4. Classes and Objects
5. Inheritance , Types of inheretance
6. Polymorphism
7. Encapsulation
6. Abstraction

Object Oriented Programming
?The object-oriented paradigm is a
programming methodology that
promotes the efficient design and
development of software systems
using reusable components that
can be quickly and safely assembled
into larger systems.
?The main aim of object-oriented
programming is to implement real-
world concepts like
?Object ? real world entity
?Classes ? Templates/ Blueprints
?Abstraction ? Visibility Controls
?Inheritance ? Backward
Compapatibilty , parent child relation
?Polymorphism ?Many forms

Why OOP
Worst thing is that
Requirement
always change

WHY OOP
? Break down requirements into objects with responsibilities,
not into functional steps
Procedural approach ? Object Oriented Approach
? Easier to Model Real things
? To make software projects more manageable and predictable.
? For more re-use code and prevent ��reinvention of
wheel�� every time.
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Components Of OOP
?Class
A class is a group of objects which have
common properties. It is a template or
blueprint from which objects are
created. It is a logical entity.
-It is non primitive data type.
-It can't be physical(no memory space)
-Class members are access modifiers,
objects , Methods , Instance variable
and constructors.
?Object
- An Object is an Instance of a class
Any entity that has state and behavior is
known as an object.
For example a chair, pen, table,
keyboard, bike, etc. It can be physical or
logical.
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Programming Representation Of a Class and Object
//Defining a Student class.
class Student{
//defining fields
int id; //field or data member or instance variable
String name;
//creating main method inside the Student class
public static void main(String args[]){
//Creating an object or instance
Student s1=new Student();//creating an object of Student
//Printing values of the object
System.out.println(s1.id);//accessing member through reference variable
System.out.println(s1.name);
}
}
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Principles of OOPs
?Inheritance:
- Inheritance is a mechanism in which one object acquires all the properties and behaviors of a
parent object.
- Inheritance represents the IS-A relationship which is also known as a parent-child relationship.
- Like Animal is a Mammals , Reptiles or Birds.
? Terms used in Inheritance
- Sub Class/Child Class/drived/extended ? inherits from other class
- Super Class/Parent Class/ Base class ? Superclass is the class from where a subclass inherits
the features.
- Reusability: As the name specifies, reusability is a mechanism which facilitates you to reuse
the fields and methods of the existing class when you create a new class. You can use the
same fields and methods already defined in the previous class.
? Types Of inheritance:
- Single ? Class B ? Class A
- Multilevel ? class C ? Class B ? class A
- Hierarchical ? Class B ? class A , Class C ? class A
- Multiple ? Class C ? class A , class C ? class B ( not supported by java, ambiguity )
- Hybrid ? class D ? class B and C , Class B and C ? Class A
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Programming Representation of Inheritance
? The syntax of Java Inheritance
class Subclass-name extends Superclass-name
{
//methods and fields
}
Example:
class Employee{
float salary=40000;
}
class Programmer extends Employee{
int bonus=10000;
public static void main(String args[]){
Programmer p=new Programmer();
System.out.println("Programmer salary is:"+p.salary);
System.out.println("Bonus of Programmer is:"+p.bonus);
}
}
OUTPUT: Programmer salary is:40000.0 , Bonus of programmer is:10000
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Principles of OOPs
?Polymorphism
If one task is performed by different ways, it
is known as polymorphism.
For example: To convince the customer
differently, to draw something, like shape,
triangle, rectangle , a cat speaks meow, dog
barks woof, etc.
- Polymorphism present a method that
can have many definitions.
Polymorphism is related to
- Overloading ? Compile time
polymorphism/run time polymorphism
- Overriding ? Run time polymorphism/
Dynamic polymorphism
- Syntax
getPrice()
getPrice(string name)
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Principles of OOP
?Encapsulation
- Encapsulation is the integration of
data and operations into a class.
- Encapsulation is hiding the
functional details from the object
calling it.
- Examples
- A capsule
- Can you drive the car?
�C Yes, I can!
? So, how does acceleration work?
�C Huh?
? Details encapsulated (hidden)
from the driver.
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Principles of OOP
?Abstraction
Abstraction is basically hiding the
implementation and gain access to
there functionality by exposing by
extend keyword.
-An abstract class is a class that may
not have any direct
instances.
-An abstract operation is an operation
that it is
incomplete and requires a child to
supply an
implementation of the operation.
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Object Oriented Programming

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