Top 10 Object Oriented Programming Interview Questions

Object oriented Programming is a widely used paradigm in many programming languages. Here are top 10 Object Oriented Programming Interview Questions that you must prepare to demonstrate your knowledge.

Object Oriented Programming Interview Questions

  1. What is the primary rule of Object oriented Programming?

The primary rule of Object Oriented Programming is that the user of an object should not know the detailed working or implementation of the object. The object must provide interface in form of methods and attributes to use it. In short a user never gets to know about the inside of the object. Just like a user drives a car without caring to know about how the engine converts gas or battery power into motion of the car.

  1. What are the characteristics of Object Oriented Programming?
  • Everything in an object Oriented Program is an object.
  • Objects constitute of data members (variables) and methods which access and manipulate the member variables.
  • A program may contain different objects which interact with each other to complete a task.
  • Objects communicate by passing messages (data values to data members)
  • A class is a blueprint (type) of an object. The object is called an instance of class having different values for its data members from others objects of the same class
  1. How does an object exist in a program?

Every object in an Object Oriented Program exists with an identity, data values, its state and its behavior in terms of methods that can be executed for the object.

  1. What is a class?

A class is defined as a software template or blueprint that defines class methods and class variables to make and use an Object in a program.

  1. Why Object Oriented Programming is efficient?

It improves efficiency by

  • Defining template to classifying objects.
  • Providing a mechanism to reuse existing class and make them interact with each other.
  • Implementing the real world behavior of objects.
  1. Differentiate between a class and an object.
  • A class is a template defining the attributes and behavior of a type of object. Object is an instance of the class.
  • A class is defined once. Any number of objects can be created using the class definition.
Objects and Class
  1. What is abstraction?

It is the most important process in OOPS where the general and relevant concepts are created from a complex concept. The goal of abstraction is to simplify a complicated system.

  1. What is encapsulation?

This is the supporting process of Abstraction wherein the complex system is simplified by hiding the implementation details of a class from its users. The access specifier- Public, Protected and Private, are used to control the access of member methods and data members. Encapsulation also enforces data hiding to prevent object data from unauthorized access by other classes.

  1. What is Private and Public access Specifiers?

The public and private access specifiers  allow data protection  and hiding in an object. A public data member can be accessed externally by other classes and internally within same class. A private data member can be accessed only by the member functions of the same class. A public method can be called externally and internally in a class. A private member function can be called only internally with in the class.

  1. What is Protected access specifier?

Protected access specifier allows a data member to be accessed by the immediate derived class or within same class.

These are the most common and frequently asked top 10 Object Oriented Programming Interview Questions. The next set of such questions are followed in next posts. We would be glad to learn which Object Oriented Programming Interview Questions you faced. Do share…

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