OOP concept in Java

Hi Guys !!! So this blog is all about the Object Oriented Programming  concepts . Lets start from the very basic concept of Object and Class .

What is an Object ?
Well It is the most basic concept and a key to understand the Object-Oriented programming . Object is an entity that has two characteristics ,  State and Behavior . Some examples of real world object can be : Bike , Chair , Dog etc. 

Lets take an example of a Bike . Bike has some state ( current gear , current speed ) and behavior ( change gear , apply brake ) . One way to begin thinking in an object-oriented way is to identify the state and behavior of real world objects .

Software objects are also similar to the real world objects. They too contains State and Behavior . An Object stores its state in  fields and exposes the behavior through methods.



What is Class ?
Class is a blueprint from which objects of same type can be created . Lets take an example of a Bike again . There are thousands of  bikes with the same characteristics i.e having same make and model . They are created from the same prototype / blueprint called class.


 Now we know the basics of an Object and  Class , so lets move on to Object Oriented principles

• Inheritance 
• Polymorphism
• Abstraction 
• Encapsulation

1. Inheritance :
Inheritance is the capability of one class to acquire the common state and behavior of   another class while adding its own functionality . In Object Oriented programming  , the concept of inheritance provides the idea of re-usability .  This means we can add additional features to a class without modifying it. 

How to achieve Inheritance in Java ?
extends keyword is used to inherit features of a class . 

class Parent {
// Parent has some state and behavior
}

class Child extends Parent {
// Inherit the common state and behavior of Parent class.
// Provide additional functionality.
}

2. Polymorphism :
Polymorphism means ability of one type to take more than one form . This can also be applied in Java where in sub-classes of a class can define their own unique behaviors and yet share some of the common functionalites of the parent class.

Example : 
Lets take an example of Bike . A company can produce different kind of bikes say , a mountain bike , and a roadbike . Now the two different types of bikes inherit the common features of a bike but also define their own separate features.

How to achieve Polymorphism in Java ? 
Overloading  and Overriding are the two ways to achieve Polymorphism.


3. Abstraction :
Abstraction is an essential element of Object Oriented programming . It refers to the act of presenting essential features without including the background details or explanations.

We can say that abstraction is purposeful suppression , hiding of some details of a process or artifact , in order to bring out more clearly other aspects , details or structures. Abstraction can be of control ( abstraction of actions ) or data . 

How to achieve Abstraction in Java ? 
Abstract classes and Interfaces are used to achieve Abstraction in Java.


4. Encapsulation :
Encapsulation is the binding of data and its associated functions in a single unit called Class . Access to the code and data inside the wrapper is tightly controlled through a well defined interface. Encapsulation provides a protective barrier that prevents the access of code and data from outside the class. 

The main benefit of encapsulation is the ability to re-factor the implemented code without breaking the code of others and thus provides flexibility and maintainability .