Important interview OOPs concepts that you need to know

Important interview OOPs concepts that you need to know

When it comes to technical interviews, OOPs concepts are the most dominating ones. If your OOPs concepts are strong, then chances are you’ll stand out among others in that interview. Here, we’ve curated all the OOPs concepts that you should definitely be knowing in order to ace that interview!

Most commonly asked interview questions (basic ones)

  • Programming paradigm – It refers to the method of solving problems using any programming language. It is an approach by which we solve a problem using available tools and resources.

    Types of programming paradigms –
    Imperative programming– In this type of programming, we dictate the computer to do things. We give detailed instructions with a specific order.
    Procedural programming– As the name suggests, it has “procedures”, also known as “functions”. In this, to increase organization or modularity, program execution is subdivided into functions.
  • Structured programming – In this, instructions after instructions are executed, one after another, and no jumping is allowed. The whole program gets divided into a single structure.
  • What do you mean by OOPs?
    OOPs, short for Object Oriented Programming, refers to the usage of objects in programming. Here, objects perform our tasks. In OOPs, we implement, inheritance, polymorphism, abstraction, etc.
  • Need for OOPs
    OOPs helps us by dividing our program into objects, which leads to increased productivity. Our code reusability gets enhanced, hence saving development time.
  • Features of OOPs
    Classes, Objects, Inheritance, Polymorphism, Data Abstraction, and Encapsulation.
  • Languages that support OOPs
    Java, Python, C++, etc

Conceptual OOPs questions (definition of keywords)

  • Class – For creating objects, we use classes as a blueprint. It defines instructions to build the object. How an object will behave and will contain, is decided by class only. For example, consider car as a class, it has various characteristics like brakes, steering wheels, brakes, etc.
  • Object – The instance of a class is known as an object. It is a physical and logical entity. It consists of state and behavior. For example, if you consider car as a class, then Porche, Jaguar, Swift, etc would be the objects of that class.
  • Interface – It is a way of describing the class’s behavior without implementation. It consists of static constants and abstract methods.
  • Encapsulation – In encapsulation, we bind together data and functions that manipulate them. It restricts direct access to the components of the object.
  • Abstraction – The details and implementation are hidden in abstraction. It aims to hide unnecessary details from the user.
  • Polymorphism – It means “having many forms”. It can process objects differently, based on their class and data types.
  • Inheritance – This is known as an inheritance when a class derives features from another class. The derived class will inherit all the properties from the class it derived from.
  • Constructor – To initialize objects, we use a constructor. It gets called automatically whenever the object is created.
  • Destructor – It works the opposite compared to the constructor. It destroys the object whenever it gets out of scope or when called explicitly to destroy.


These are the most important concepts of Object Oriented Programming language. You need to know them deeply in order to understand the workflow. Get yourself prepared with these concepts and you’ll never think twice before answering OOPs questions in interviews.

Happy learning!

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