OOPs Interview Questions: Prep for Success
In today’s competitive job market, technical interviews often serve as the deciding factor between candidates with similar educational backgrounds. Among the wide range of topics recruiters explore, OOPs interview questions consistently feature across entry-level, mid-career, and even senior technical roles. That’s because Object-Oriented Programming (OOP) is not just a programming style—it’s a foundation of modern software design, enabling scalable, reusable, and efficient systems.
For professionals aiming to transition into software development, strengthen coding expertise, or prepare for roles in emerging fields like data science, cloud computing, and AI-driven platforms, a strong grip on OOPs concepts interview questions is critical. This blog provides a structured guide to help you prepare thoroughly, practice confidently, and align your knowledge with industry expectations.
Table Of Content
The Role of OOP in Career Growth
Top OOPs Interview Questions
How Jaro Helps
Turning Preparation into Opportunity
Frequently Asked Questions
The Role of OOP in Career Growth
Have you ever walked into a job interview, only to be caught off guard by technical questions that seemed deceptively simple at first glance? Many professionals face this challenge, especially when it comes to OOPs interview questions. Object-Oriented Programming (OOP) is a cornerstone of modern software development, and recruiters often use these questions to evaluate not only coding ability but also problem-solving skills and conceptual clarity.
In today’s evolving job market, mastering these concepts isn’t just about acing interviews—it’s about staying competitive in an industry where upskilling has become essential. With IT, fintech, e-commerce, and emerging fields relying heavily on object-oriented design, preparing for OOPs interview questions is one of the smartest moves for career growth.
Whether you are looking to switch domains, step into a software development role, or strengthen your technical foundation, this blog will guide you through the most important questions, patterns, and preparation strategies. Let’s explore how you can approach OOPs concepts and interview questions with confidence.
Top OOPs Interview Questions
Below is a structured list of frequently asked OOPs interview questions, complete with explanations, examples, and comparisons to help you prepare thoroughly.
Beginner-Level OOPs Interview Questions
1. What is Object-Oriented Programming (OOP)?
This is often the very first oops interview question. Interviewers want to test your conceptual foundation.
Answer Approach:
- OOP is a programming paradigm built around objects and classes.
- It emphasizes reusability, modularity, and scalability.
- Key principles: Encapsulation, Inheritance, Polymorphism, and Abstraction.
Why it’s asked: To check if you can explain technical concepts in simple terms.
2. What are the four pillars of OOP?
This is one of the most commonly repeated OOPs concepts interview questions.
| Pillar | Definition | Example (Java) |
|---|---|---|
| Encapsulation | Bundling data and methods into one unit (class). | Getters and Setters |
| Inheritance | Reusing properties/methods from another class. | class Dog extends Animal |
| Polymorphism | One interface, many implementations. | Method Overloading/Overriding |
| Abstraction | Hiding complexity, showing only essentials. | Abstract Classes, Interfaces |
Tip: Use real-world analogies to make your answer clear.
3. What is the difference between Class and Object?
A fundamental but important OOPs interview question.
- Class: Blueprint (e.g., Car design).
- Object: Instance of a class (e.g., a specific car like Tesla Model 3).
4. Explain the difference between Overloading and Overriding.
A favorite in Java OOPs interview questions.
| Aspect | Overloading | Overriding |
|---|---|---|
| Definition | Same method name, different parameters | Same method name, same parameters |
| Compile/Runtime | Compile-time | Runtime |
| Usage | Improves readability | Provides specific implementation |
5. What are Constructors in OOP?
This oops concepts in java interview question tests your knowledge of how objects are initialized in OOP.
- Special methods invoked at object creation.
- Same name as the class.
- Don’t have a return type.
Follow-up in Java OOPs Interview Questions:
- Difference between default, parameterized, and copy constructors.
6. What is the difference between Abstraction and Encapsulation?
A tricky OOPs concepts in Java interview question.
- Encapsulation: Focuses on “how” the data is hidden.
- Abstraction: Focuses on “what” functionalities are exposed.
| Feature | Abstraction | Encapsulation |
|---|---|---|
| Purpose | Hides implementation details | Restricts access to data |
| Example (Java) | Abstract Class/Interface | Private variables + Getters/Setters |
7. What is the difference between Interface and Abstract Class?
Common in Java OOPs interview questions.
- Interface: 100% abstraction (Java 7).
- Abstract Class: Can have both abstract and concrete methods.
- Interfaces support multiple inheritance; abstract classes do not.
8. What is Polymorphism in OOP?
This is one of the most frequent OOPs concepts interview questions.
- Compile-time Polymorphism: Method overloading.
- Runtime Polymorphism: Method overriding.
9. What is the difference between Composition and Aggregation?
This oops interview question helps check if you can explain relationships between objects.
| Concept | Definition | Example |
|---|---|---|
| Aggregation | “Has-a” relationship, weaker bond | Department has Employees |
| Composition | Stronger bond; child object cannot exist without parent | Engine inside Car |
10. What is the significance of the this and super keywords in Java?
This oops interview question tests your practical Java knowledge on referencing instances and parents.
- this: Refers to current class instance.
- super: Refers to parent class object.
11. Why is OOP important in the industry today?
Professionals are often asked to connect OOP theory with its real-world impact.
Market Perspective:
- Widely used in enterprise systems, cloud platforms, and AI frameworks.
- Easier code maintainability and collaboration in large teams.
Salary Snapshot:
| Role | Average Salary (India, 2024)* |
| Java Developer | ₹6–10 LPA |
| Software Engineer | ₹5–9 LPA |
| Full Stack Developer | ₹7–12 LPA |
12. Advanced-Level OOPs Interview Questions
These oops interview questions explore deeper applications of OOP principles in real projects.
- How does Java achieve platform independence while still being object-oriented?
- Can multiple inheritance be achieved in Java? (Yes, via interfaces.)
- Explain the difference between shallow copy and deep copy.
- How do access modifiers (public, private, protected) enforce encapsulation?
- What are design patterns in OOP, and why are they useful?
13. What is Dynamic Binding in OOP?
This oops interview question tests if you understand runtime method resolution.
- Definition: Linking of a function call to the actual implementation at runtime.
- Example (Java): Method overriding uses dynamic binding.
14. Differentiate between Shallow Copy and Deep Copy.
This oops interview question checks your grasp of memory and object handling.
- Shallow Copy: Copies object references, not the actual objects.
- Deep Copy: Creates independent copies of objects.
- Use Case: Cloning objects in Java (clone() method).
15. What are Access Modifiers in OOP?
This java oops interview question checks how well you understand encapsulation controls.
- Public: Accessible everywhere.
- Private: Accessible only within the class.
- Protected: Accessible within the package and subclasses.
- Default (package-private): Accessible only within the same package.
Intermediate-Level OOPs Interview Questions
16. What is the significance of final keyword in Java OOPs?
This oops interview question is asked to test restrictions in OOP design.
- final class: Cannot be inherited.
- final method: Cannot be overridden.
- final variable: Value cannot be changed (constant).
17. What is a Static Method in OOP?
This oops concepts in java interview question checks knowledge of class-level behavior in OOP.
- Belongs to the class, not to an object.
- Can be called without creating an instance.
- Example: Math.sqrt() in Java.
18. What are Friend Functions in C++ OOP?
This java oops interview question explores access control differences across languages.
- Special functions that can access private/protected members of a class.
- Not available in Java (ensures stronger encapsulation).
19. What is the difference between == and equals() in Java?
This oops concepts in java interview question evaluates your understanding of reference vs. value comparison.
- ==: Compares memory references.
- equals(): Compares values (overridden in classes like String).
20. Explain the concept of Copy Constructor.
This oops concepts in java interview question checks if you understand object duplication.
- Constructor that initializes an object as a copy of another object.
- Used in C++ and other OOP languages.
21. What is Multiple Inheritance, and does Java support it?
This oops interview question is asked to test your understanding of inheritance complexities.
- Definition: A class can inherit from more than one parent.
- In Java: Not supported through classes (avoids ambiguity). Achieved through interfaces.
22. What is Diamond Problem in OOP?
This java oops interview question checks your awareness of inheritance-related issues.
- Occurs in multiple inheritance when two parent classes have the same method.
- In Java, solved using interfaces and default methods.
23. What is Method Hiding in Java?
This oops interview question tests knowledge of static methods and inheritance rules.
- Happens when a subclass defines a static method with the same signature as a static method in the parent class.
- It is not overriding; rather, it hides the parent method.
24. Differentiate between Abstract Class and Interface (Advanced).
This oops interview question checks deeper design-level understanding in Java.
| Aspect | Abstract Class | Interface |
|---|---|---|
| Multiple Inheritance | Not supported | Supported |
| Methods | Can be abstract + concrete | Default methods (Java 8+) |
| Variables | Instance + static variables | Only public static final vars |
25. What are Virtual Functions in OOP?
This java oops interview question evaluates your understanding of runtime polymorphism in C++.
- Functions declared in base class with virtual keyword (C++).
- Enable runtime polymorphism.
26. What is Constructor Chaining in Java?
This oops interview question is asked to check knowledge of constructor usage in inheritance.
- One constructor calling another within the same class or parent class using this() or super().
- Improves code reusability.
27. What is an Anonymous Inner Class in Java?
This oops concepts in java interview question tests your familiarity with specialized classes in Java.
- A class without a name, defined and instantiated at the same time.
- Often used for event handling and threading.
28. What is Object Cloning in OOP?
This oops interview question checks how well you understand object duplication mechanisms.
- Creating a copy of an object.
- Achieved in Java using clone() method of Object class.
29. Differentiate between Association, Aggregation, and Composition.
This oops interview question tests your clarity on object relationships.
| Concept | Definition | Example |
|---|---|---|
| Association | General relationship between two classes | Teacher–Student |
| Aggregation | Weak “has-a” relationship | Department–Employee |
| Composition | Strong “part-of” relationship | Car–Engine |
30. What are Getter and Setter Methods?
This evaluates your understanding of encapsulation.
- Getters: Retrieve values of private variables.
- Setters: Modify values of private variables.
- Support encapsulation.
31. What is Late Binding in OOP?
This oops interview question tests understanding of runtime polymorphism.
- Method implementation is determined at runtime (runtime polymorphism).
- Example: Overridden methods in Java.
Advanced-Level OOPs Interview Questions
32. What is a Singleton Class in OOP?
This is asked to check knowledge of design patterns.
- A class that allows only one instance during runtime.
- Used in logging, database connections, configuration management.
- Achieved in Java using a private constructor and a static instance method.
33. What is Data Hiding in OOP?
This checks your grasp of encapsulation in practice.
- Restricting access to internal data members of a class to ensure security and maintain integrity.
- Achieved using private/protected access modifiers.
34. Differentiate between Compile-time and Runtime Polymorphism.
This oops interview question evaluates your clarity on polymorphism types.
| Type | Example | Binding |
|---|---|---|
| Compile-time | Method overloading | Early binding |
| Runtime | Method overriding | Late binding |
35. What is Method Signature?
This checks if you know the structure of a method definition.
- Composed of method name and parameter list.
- Return type is not part of the method signature in Java.
36. What are Pure Virtual Functions in C++?
This tests your knowledge of abstract functionality in C++.
- Functions with no implementation in base class.
- Declared with =0.
- Forces derived classes to implement them (similar to interfaces in Java).
37. What is a Destructors’ Role in OOP?
This oops interview question question checks how you handle resource cleanup.
- Special method invoked when an object is destroyed.
- In C++, begins with ~.
- In Java, garbage collection handles destruction (no explicit destructors).
38. Differentiate between Composition and Inheritance.
This checks your understanding of design choices.
- Inheritance: Reuse code via parent-child relationship.
- Composition: Reuse by including objects of other classes.
39. What is the difference between Deep Inheritance and Shallow Inheritance?
This oops interview question evaluates how well you understand hierarchy depth.
- Shallow inheritance: 1–2 levels of inheritance.
- Deep inheritance: Multiple levels (grandparent–parent–child).
- Deep inheritance may reduce clarity.
40. Explain Cohesion and Coupling in OOP.
This is asked to test knowledge of design principles.
- Cohesion: How closely related functions in a class are.
- Coupling: Degree of dependency between classes.
- Goal: High cohesion, low coupling.
41. What are Sealed Classes (Java 15+)?
This oops interview question checks awareness of modern Java features.
- Classes that restrict inheritance to specific permitted subclasses.
- Helps control class hierarchies.
42. What is the significance of instanceof operator in Java?
This evaluates your knowledge of type-checking in Java.
- Tests whether an object is an instance of a specific class or subclass.
43. Differentiate between Static and Dynamic Polymorphism.
This tests your clarity on compile-time vs runtime binding.
- Static: Resolved at compile time (overloading).
- Dynamic: Resolved at runtime (overriding).
44. What is Message Passing in OOP?
This java oops interview question checks understanding of how objects interact.
- Objects communicate by sending messages (method calls).
- Example: object.methodName() in Java.
45. What is Object Slicing in C++?
This oops interview question question tests understanding of object assignment behavior.
- When a derived class object is assigned to a base class object, derived members are sliced off.
46. What is Data Abstraction vs. Data Encapsulation (Advanced)?
This java oops interview question checks deeper clarity on OOP principles.
- Abstraction: Hides details, shows essentials.
- Encapsulation: Restricts direct access and bundles data with methods.
47. What are Static Blocks in Java?
This oops interview question evaluates knowledge of class initialization in Java.
- Block of code inside a class, executed once when the class is loaded.
- Useful for initializing static variables.
48. What is Method Chaining in OOP?
This java oops interview question tests your knowledge of fluent APIs.
- Technique where multiple methods are invoked in a single statement.
- Example: builder.setName(“X”).setAge(25).build();
49. What is an Abstract Method?
This oops interview question checks if you understand enforced abstraction.
- A method without implementation.
- Declared in abstract classes or interfaces.
- Must be overridden in subclasses.
50. What is Object Serialization?
This java oops interview question evaluates your knowledge of data persistence.
- Process of converting an object into a byte stream for storage or transmission.
- In Java: Achieved using Serializable interface.
51. Explain the difference between Early Binding and Late Binding.
This java oops interview question checks your grasp of method resolution timing.
- Early binding: Method call resolved at compile time.
- Late binding: Method call resolved at runtime.
52. What are Nested Classes in Java?
This oops interview question evaluates your understanding of class organization.
- Classes defined inside another class.
- Types: static nested class, inner class, local inner class, anonymous inner class.
How Jaro Helps
Preparing for OOPs interview questions is only one part of building a career in technology. To stand out, professionals need structured learning, mentorship, and industry-relevant programs. This is where Jaro Education plays a pivotal role.
- About Jaro Education: A trusted service partner offering access to top-tier programs in collaboration with leading institutions like IITs, IIMs, and international universities.
- USP: Personalized counseling, flexible online learning formats, and value-added services through Jaro Connect.
Program Highlights for Aspiring Technologists
Online BCA Programme – Manipal University Jaipur
- Duration: 3 years
- Curriculum: Covers core computer science subjects, software engineering, and industry projects.
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By enrolling through Jaro, you don’t just gain access to learning materials—you gain a mentor, a guide, and a career partner who understands market dynamics.
Turning Preparation into Opportunity
Facing OOPs interview questions can feel intimidating, but with the right preparation and resources, you can transform them into an opportunity to showcase your expertise. In a world where technology drives every sector, building strong foundations in OOP ensures you remain adaptable, confident, and career-ready.
Remember the question we started with, how do you avoid being caught off guard in an interview? The answer lies in structured preparation, continuous upskilling, and choosing learning partners who guide you at every step. With Jaro Education, you gain more than a program—you gain a pathway to growth.
Take the next step, explore exclusive programs, and let Jaro be your trusted partner in unlocking new professional opportunities.
Frequently Asked Questions
Yes. Many of Jaro’s programs are built specifically for career transitions, offering capstone projects, real-world case studies, and internship or project support that enhances domain shift readiness.
Most programs offered through Jaro are designed to support learners from diverse backgrounds. While prior programming knowledge is helpful for technical courses, many programs start with foundational concepts before moving into advanced topics. Personalized counseling can help you select a program that matches your current skill level.
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