Top 25 OOPs Interview Questions and Answers (2026 Edition)

In 2026, software interviews are no longer about memorizing syntax—they are about how well you think in terms of design, structure, and scalability. This is exactly why OOPs Interview Questions continue to dominate technical interviews for freshers across service-based and product-based companies. Whether you are preparing for your first campus placement or an entry-level developer role, Object-Oriented Programming (OOPs) remains a non-negotiable skill.For fresh graduates, preparing the right OOPs Interview Questions can make the difference between clearing a technical round and getting rejected due to weak fundamentals.

Object-Oriented Programming is used as a benchmark to evaluate logical thinking, design clarity, and long-term engineering potential. Many freshers fail OOPs interviews not because the concepts are complex, but because they lack conceptual depth and practical explanation skills. This article is written specifically for freshers preparing in 2026, offering a well-structured and interview-focused collection of OOPs Interview Questions and Answers. By the end of this guide, you will not only know the correct answers but also understand how to explain them confidently in real interviews.

Overview: What Are OOPs and Why Do They Matter?

Object-Oriented Programming (OOP) is a programming paradigm that organizes software around objects rather than functions or logic alone. Each object represents a real-world entity and combines both data and behavior into a single unit.

OOPs are important because they help developers:

• Build modular and reusable code
• Improve maintainability and scalability
• Model real-world problems more naturally
• Manage large and complex software systems

In interviews, OOPs Interview Questions are used to test how well a candidate understands software design principles rather than just language syntax.This is why most companies rely heavily on OOPs Interview Questions to evaluate a candidate’s problem-solving and design-thinking skills.

Core OOPs Concepts Explained

Before diving into interview questions, it is essential to understand the four core pillars of OOP:

• Encapsulation – This means keeping the data and the actions that work on that data together in one place, like a capsule. It also hides the details so others can’t change it directly, keeping things safe and organized.
• Abstraction – This is about showing only what’s necessary and hiding the complicated details. Think of it like using a TV remote without needing to know how the TV works inside.
• Inheritance – This allows a new class to take properties and actions from an existing class, so you don’t have to write the same code again. It’s like a child inheriting traits from their parents.
• Polymorphism – This lets the same action work in different ways depending on the object. For example, the word “draw” can mean drawing a circle, a square, or a triangle depending on the shape.

Most OOPs Interview Questions are built around these concepts, either directly or through scenario-based problems.

Top 25 OOPs Interview Questions and Answers

These OOPs Interview Questions are carefully selected based on real fresher interviews and common technical screening patterns in 2026.

1. What is Object-Oriented Programming?

Object-Oriented Programming is a programming approach where software is designed using objects that represent real-world entities. Each object contains data and methods to operate on that data, making programs modular, reusable, and easier to maintain.

2. What is a class?

A class is a blueprint or template used to create objects. It defines the properties and behaviors that the objects created from it will have.

3. What is an object?

An object is an instance of a class. It represents a real-world entity and occupies memory. Objects interact with each other using method calls.

4. What is encapsulation, and give a real-world example?

Encapsulation is the process of binding data and methods together into a single unit and restricting direct access to data using access modifiers. It improves security and data integrity.
Real-world example: Consider a bank account class. The account balance is private, and you can only access it through methods like deposit() and withdraw(). This prevents unauthorized changes to the balance.

5. What is abstraction, and give a real-world example ?

Abstraction focuses on hiding implementation details and exposing only essential features. It helps reduce complexity and improves code readability.
Real-world example: Think of a car. You interact with it using methods like start(), accelerate(), and brake(), without needing to know the internal engine mechanics.

6. Difference between abstraction and encapsulation?

Feature	Abstraction	Encapsulation
Purpose	Hides implementation details, shows only essential features	Restricts direct access to data and methods
Focus	Design and functionality	Implementation and data security
Implementation	Achieved using abstract classes and interfaces	Achieved using access modifiers (private, protected, public)
Example	Showing only the method signature to the user	Using getters and setters to access private variables

This comparison is frequently tested in OOPs Interview Questions and Answers to assess conceptual clarity.

7. What is inheritance?

Inheritance allows a child class to acquire properties and methods from a parent class. It promotes code reusability and hierarchical relationships.

8. What are the types of inheritance?

Common types of inheritance include:

• Single inheritance – A child class inherits from one parent class, allowing reuse of its properties and methods.
• Multilevel inheritance – A class inherits from a child class, forming a chain of inheritance across multiple levels.
• Hierarchical inheritance – Multiple child classes inherit from a single parent class, sharing its features.
• Multiple inheritance – A class inherits from more than one parent class; in Java, this is achieved using interfaces.

9. What is polymorphism?

Polymorphism allows the same method or interface to behave differently based on the object calling it. It enables flexibility and dynamic behavior in programs.

10. What are types of polymorphism?

• Compile-time polymorphism (method overloading) – Occurs when multiple methods in the same class have the same name but different parameters; the correct method is chosen at compile time.
• Runtime polymorphism (method overriding) – Happens when a subclass provides a specific implementation of a method defined in its parent class; the method to execute is determined at runtime.

11. What is method overloading?

Method overloading allows multiple methods with the same name but different parameters in the same class. It improves code readability and flexibility.

12. What is method overriding?

Method overriding occurs when a child class provides a specific implementation of a method already defined in the parent class. It supports runtime polymorphism.

13. What is a constructor and what are the rules for defining a constructor?

A constructor is a special method used to initialize objects. It has the same name as the class and is automatically called when an object is created.

Rules to define a constructor:

1. The constructor name must exactly match the class name.
2. It does not have a return type, not even void.
3. It is automatically invoked when an object is created.
4. A class can have multiple constructors (constructor overloading) with different parameter lists.
5. If no constructor is defined, the compiler provides a default constructor.

Example in Java:

class Car {
    String model;
    
    // Constructor
    Car(String modelName) {
        model = modelName;
    }
    
    void display() {
        System.out.println("Car model: " + model);
    }
}

public class Main {
    public static void main(String[] args) {
        Car myCar = new Car("Tesla Model 3");
        myCar.display();
    }
}

14. Can constructors be overloaded?

Yes, constructors can be overloaded to initialize objects in different ways using different parameter lists. For example, in Java:

class Student {
    String name;
    int age;

    // Default constructor
    Student() {
        this.name = "Unknown";
        this.age = 0;
    }

    // Parameterized constructor
    Student(String name, int age) {
        this.name = name;
        this.age = age;
    }

    void display() {
        System.out.println("Name: " + name + ", Age: " + age);
    }
}

public class Main {
    public static void main(String[] args) {
        // Using default constructor
        Student s1 = new Student();
        s1.display(); // Output: Name: Unknown, Age: 0

        // Using parameterized constructor
        Student s2 = new Student("Alice", 20);
        s2.display(); // Output: Name: Alice, Age: 20
    }
}

In this example, the Student class has two constructors: one without parameters and one with parameters. This demonstrates constructor overloading, allowing objects to be initialized in different ways.

15. What is an interface?

An interface defines a contract that specifies method signatures without implementation. Classes implementing the interface must provide method definitions.

16. What is difference between Abstract class and interface?

An abstract class can have both abstract and concrete methods, can have constructors, and supports single inheritance, while an interface mainly contains abstract methods, cannot have constructors (except default in some languages), and supports multiple inheritance. Here’s a table summarizing the differences:

Feature	Abstract Class	Interface
Methods	Can have abstract and concrete methods	Mainly abstract methods (default/concrete allowed in some languages)
Constructors	Can have constructors	Cannot have constructors
Inheritance	Supports single inheritance	Supports multiple inheritance
Access Modifiers	Can have private, protected, public	Methods are usually public by default

17. What is data hiding?

Data hiding restricts direct access to internal data using access modifiers like private or protected, improving security and control.

18. What are access modifiers?

Access modifiers control the visibility of classes, methods, and variables, determining which parts of a program can access them:

• Public – Accessible from any other class.
• Private – Accessible only within the same class.
• Protected – Accessible within the same class, subclasses, and classes in the same package.
• Default – Accessible only within the same package when no modifier is specified.

19. Difference between dynamic binding and static binding

Dynamic binding is when the method call is resolved at runtime, allowing polymorphic behavior. Static binding is when the method call is resolved at compile time, typically for private, final, or static methods.

Feature	Dynamic Binding	Static Binding
Time of Resolution	Resolved at runtime	Resolved at compile time
Method Behavior	Method can behave differently based on object instance	Method behavior is fixed and cannot change at runtime
Polymorphism	Supports runtime polymorphism	Does not support runtime polymorphism
Associated Methods	Typically used with overridden methods	Typically used with static, private, or final methods
Flexibility	More flexible, allows dynamic method selection	Less flexible, method calls are predetermined

20. What is the “this” keyword?

The this keyword refers to the current object instance and helps differentiate between instance variables and method parameters.

21. What is the “super” keyword?

The super keyword is used to access parent class methods, variables, or constructors. For example, if a parent class Animal has a method eat(), a child class Dog can call super.eat() to invoke the parent’s version of the method. Similarly, super() can be used in the child class constructor to initialize the parent class.

22. What is object cloning?

Object cloning creates an exact copy of an object. For example, in Java, using the clone() method on an object of class Person will create a new Person object with the same field values. It can be shallow, where only the object itself is copied but references point to the same objects, or deep, where all nested objects are also cloned to create completely independent copies.

23. What is composition?

Composition is a way to build objects by including other objects inside them, showing a “has-a” relationship. For example, a car object can have an engine object inside it. This approach makes programs more flexible and easier to change because you can replace or modify parts without affecting the whole system. It is often preferred over inheritance when you want to combine behaviors without creating a strict parent-child relationship.

24. What is loose coupling?

Loose coupling is a design principle where classes or components have minimal knowledge of each other’s internal details. This reduces dependencies, allowing changes in one class without significantly affecting others. It enhances code maintainability, testability, and flexibility, making it easier to extend or modify the system. By promoting independent modules, loose coupling also improves readability and supports better software architecture practices.

25. What is tight coupling?

Tight coupling occurs when classes are highly dependent on each other, meaning that a change in one class often requires changes in the other. This strong inter-dependency makes the code harder to maintain, test, and extend. It reduces flexibility because objects cannot function independently, and it increases the risk of introducing bugs when modifications are made. In contrast, loosely coupled systems are preferred as they promote modularity and easier maintenance.

Common Mistakes Freshers Make in OOPs Interviews

• Memorizing definitions without understanding
• Confusing abstraction with encapsulation
• Overusing inheritance instead of composition
• Ignoring design principles like SOLID

Avoiding these mistakes significantly improves interview performance.

Expert Tips and Best Practices

• Explain concepts using real-world examples
• Focus on why a concept is used, not just what it is
• Prefer clarity over complex code
• Practice explaining OOP concepts verbally
• Relate answers to application design and scalability

Complete Your Interview Preparation

While mastering OOPs Interview Questions and Answers builds a strong conceptual foundation, cracking real interviews requires combining OOPs with programming and database skills.

To prepare holistically for fresher interviews in 2026, continue with:

• Java Interview Questions and Answers – Ideal for service-based and product-based company interviews.
• Python Interview Questions and Answers – Perfect for scripting, backend, and automation roles.
• SQL Interview Questions and Answers – Critical for database-driven applications and backend roles.
• System Design Interview Questions and Answers – Essential for understanding scalability, performance, databases, APIs, caching, load balancing, and designing real-world applications asked in modern technical interviews.

Conclusion

Mastering OOPs Interview Questions in 2026 requires strong conceptual clarity and the ability to explain ideas logically. For freshers, OOPs serve as a foundation that interviewers use to assess long-term growth potential. By understanding core principles, practicing scenario-based explanations, and avoiding common misconceptions, you can confidently approach any OOPs interview. Object-Oriented Programming is not just a topic—it is a mindset that shapes how robust software is built. Consistent practice of well-structured OOPs Interview Questions helps freshers develop confidence and interview-ready thinking. Developing this mindset early will give you a strong advantage throughout your career.For freshers, mastering OOPs Interview Questions and Answers is one of the most reliable ways to clear technical interviews with confidence.

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