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Object Oriented Programming or OOPs is a widely used term in Computer Science . OOPs is a vital concept for every Computer Science students , it is asked not only in exams but also in jobs interviews as well .Many students find it difficult to understand these Object Oriented Programming (OOP) concepts . So I decided to write an article on it , I hope you will like it .


There are many terms in Object Oriented programing , together these terms are called as OOP s concepts . These OOP s concepts are used in all modern programming languages like Java , J2EE,C++ , C#, .Net , Python and Javascript .Lets us begin with these OOPs concepts.

Class
Class is the 1st OOPs concept .Class defines the characteristics of objects which includes its attributes , fields properties and behavior . Let us say we have a class called car , then the color , model number , top speed can be its attributes and properties . Accelerating , breaking , turning will be its behavior .

Objects

Objects can be considered as a thing that performs a set of related functions .Programming objects are used to model real worlds objects. An object is also an instant of a class . For our class Car , Ferrari will be our object

Instance
One can have an instance of a class; the instance is the actual object created at runtime. The set of values of the attributes of a particular object is called its state. The object consists of state and the behaviour that's defined in the object's class.


Method
Also called as functions in some programming languages , methods defines the behavior of particular objects . For our Car class , turning() , breaking () will be our methods .

Inheritance
In the real world there are many objects that can be specialized. In OOP, a parent class can inherit its behavior and state to children classes. This concept was developed to manage generalization and specialization in OOP .Lets say we have a class called Car and Racing Car . Then the attributes like engine no. , color of the Class car can be inherited by the class Racing Car . The class Car will be Parent class , and the class Racing Car will be the derived class or child class

The following OO terms are commonly used names given to parent and child classes in OOP:

Superclass: Parent class.
Subclass: Child class.
Base class: Parent class.
Derived class: Child class

Abstraction
Abstraction is simplifying complex reality by modeling classes appropriate to the problem . In other words it means representing only the important details without including all the details . For example the car Ferrari can be treated as simple car only .

Encapsulation
The wrapping up of data and functions into a single unit is called as encapsulation . For example the class car has a method turn () .The code for the turn() defines how the turn will occur . So we don't need to define how Mercedes will turn and how the Ferrari will turn separately . turn() can be encapsulated with both.

Polymorphism
Its an important OOPs concept , Polymorphism means taking more than one forms .Polymorphism allows the programmer to treat derived class members just like their parent class's members. More precisely, Polymorphism in object-oriented programming is the ability of objects belonging to different data types to respond to calls of methods of the same name .If a Dog is commanded to speak(), this may elicit a bark(). However, if a Pig is commanded to speak(), this may elicit an oink(). Each subclass overrides the speak() method inherited from the parent class Animal.

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