Object Oriented Programming.

Object-Oriented questions are very basic interview questions in the IT domain.

Generally, they will ask an open-ended question to get a sense of your personality and to see if you will fit into the company culture. Here interviewer checks the ability to work in an IT working environment.

What is Object Oriented Programming?

“Object-Oriented Programming is that works on the principle of objects are the most important part of your program.”

The Class,

The class is a group of similar entities.

Objects,

Objects are the instance of a class. it contains both data & functions.

There have four basic OOP concepts.

1. Inheritance.

"OOP concept, which one object had the properties and behaviors of the parent objects."

In object-oriented programming, inheritance is the mechanism of basing an object or class upon another object or class, retaining similar implementation. Also defined as deriving new classes from existing ones and forming them into a hierarchy of classes.

2. Polymorphism.

“Polymorphism is the ability of an object to take on many forms.”

Polymorphism is the ability of an object to take on many forms. The most common use of polymorphism in OOP occurs when a parent class reference is used to refer to a child class object. Any Java object that can pass more than one IS-A test is considered to be polymorphic.

3. Abstraction.

"Is an act of representing essential features without including background details."

Abstraction is selecting data from a larger pool to show only the relevant details to the object. It helps to reduce programming complexity and effort. In Java, abstraction is accomplished using Abstract classes and interfaces. It is one of the most important concepts of OOP.

4. Encapsulation.

"OOP concept of wrapping the data & code only access that data withing same class."

It refers to the bundling of data with the methods that operate on that data. Encapsulation is used to hide the values or state of a structured data object inside a class, preventing unauthorized parties' direct access to them.