Oops Interview Questions – Learn More

OOP or Object Oriented Programming is a model of programming or a paradigm in which Objects are the primary focus and everything revolves around the object. Objects are the instances of classes which basically means classes are the blueprints of how an object is formed, its characteristics and behaviors are defined within classes. You can make several objects of the same type using one class. By characteristics we mean what the object can do and what are its defining identities and by behavior, we mean how the object is doing what it is doing. Both of which can be traced back to how the parent class of the objects is defined. This model is very popular and is used extensively in many popular programming languages such as python, java, c#, etc. Keep reading to know about Oops Interview Questions.

Oops Interview Questions - Learn More

Characteristics and behavior:

In programming terms, characteristics are the properties, data, and attributes are the objects and behaviors are the different functions and methods defined within the objects. These functions can be used to retrieve the data from the functions or modify a particular attribute as well as in some cases functions.

Interview questions:

Why is OOPs needed?

OPPs are popular and useful because of many reasons. Such as:

  • It increases the readability of the code and makes it easy for the developers to understand and modify the code.
  • It makes writing scalable code far more easier and intuitive.
  • It also makes the program easy to understand even for the user even if the user doesn’t understand the actual implementation.
  • Big scale software can easily be managed with OPPs as everything can be considered as objects and classes.

What are the most popular programming languages that implement OOPs?

The most popular languages with OOPs support are C++, Java, Python, Nodejs, PHP, etc.

What are the main features of OOPs?

The main four features of Object Oriented Programming are:

  • Inheritance
  • Encapsulation
  • Abstraction
  • Polymorphism

What is a class?

Classes can be thought of as a template or blueprint of an object. Using a class one can create many objects with different reference variables. In class you create some properties and add some data, those are called the members and you can add some functions and methods which are called behavior. An object inherits the properties, attributes, methods, and functions defined in its parent class.

What is an object and how is it beneficial?

Objects are the instances of classes and the user interacts with objects. Users and the program can update objects’ properties or use its function to accomplish some task. In short objects are real-life entities that are defined upon class while class the blueprint is only used to produce required objects. Objects have properties and methods.

What is encapsulation?

Encapsulation means binding and keeping all the data and putting a capsule or envelope around that information. In the context of OOPs, encapsulation means when a number of necessary data members and functions are required to do a piece of work or execute a specific part of code are kept together as well as the unnecessary and sensitive information is hidden from the end-users. This can be understood in ways:

  • Data Hiding: Not all information is necessary to be revealed to run a program. Sometimes the extra amount of data creates junk and clutter and sometimes the data is sensitive and should be protected. This domain comes under encapsulation.
  • Data Binding: Data hiding is important so as to keep all the interlinked data together forming clear connections between them. Relating different pieces of members with other members and with the necessary methods, come under data binding.

What do you mean by polymorphism?

Poly means many and morphs means shape. So polymorphism is when a piece of code is used differently depending on the context and type of task. Such as with predefined classes we can create some objects which can have some extra new set of values, attributes, and methods and can be used differently in different situations. That is how classes and OOPs increase the reusability of a chunk of code. Polymorphism is of 2 types: Static or early binding or compile-time polymorphism and dynamic or runtime polymorphism.

What is abstraction?

After the final product is delivered to the end-user, the user knows how to operate the program to achieve certain tasks but doesn’t know how each individual piece of the program works to attain the end and desired results. The main goal of obstruction is to remove unnecessary clutter from the user experience and make the code clean and readable.

What is Inheritance?

The literal meaning of inheritance is to gain something or some behavior as a child or offspring from parents. In OOPs inheritance means to obtain the properties and methods and functions by a child class or object from a parent class. This particular feature increases the reusability of the code manifolds.

Does class consume memory?

No, A class does not consume memory. Classes are blueprints and when the actual object is initialized using the class the child object consumes memory.

Can you create objects without class?

Yes, Objects can be created without classes. Following the required syntax of a particular programming language, one can easily create objects without any blueprint or class. One can add as many properties and methods to the objects as he/she wants.

What are the various categories of inheritance? Name them.

Inheritance can be of many types such as:

  • Single inheritance
  • Multiple inheritances
  • Multi-level inheritance
  • Hierarchical inheritance
  • Hybrid inheritance

What is the difference between overloading and overriding?

Overloading is a compile-time or static polymorphism feature in which an entity has multiple implementations or usage with identical names. An Example can be, Method overloading and Operator overloading.

Whereas Overriding is a runtime or dynamic polymorphism feature in which an entity has the same name, but its implementation changes during execution or at runtime. For example, Method overriding.

What is an abstract class?

An abstract class can only be declared and not initialized. It is initialized with a different sub class. Abstract class contains different abstract methods. 


OOPs can seem hard at first but it is a very useful and effective model of programming. We recommend going through the concepts again and again until you fully grasp them.

Oops Interview Questions – Learn More

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