OOP · Principles interview questions

36 OOP · Principles questions from the Computer Science Fundamentals bank, written for Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd.

Sign up free to see every answer with its explanation and ask the AI tutor.

Practice OOP · Principles free

1. What is object-oriented programming?

Junior
  1. A.the ability of one interface or name to take many forms depending on the object or arguments
  2. B.a field whose own copy belongs to each object created from a class
  3. C.the guideline 'do not repeat yourself', avoiding duplicated logic by factoring it into one place
  4. D.a paradigm organizing software around objects that bundle data and the behavior acting on it

Answer + AI explanation with a free account

2. Which term means: "a paradigm organizing software around objects that bundle data and the behavior acting on it"?

Junior
  1. A.instance variable
  2. B.inheritance
  3. C.object-oriented programming
  4. D.message passing

Answer + AI explanation with a free account

3. Which statement is correct?

Junior
  1. A.object-oriented programming — the ability of one interface or name to take many forms depending on the object or arguments
  2. B.object-oriented programming — bundling data and methods in one unit and restricting direct external access to the internal state
  3. C.object-oriented programming — a class is the abstract template, while an object is a concrete instance occupying memory at runtime
  4. D.object-oriented programming — a paradigm organizing software around objects that bundle data and the behavior acting on it

Answer + AI explanation with a free account

4. What is class?

Junior
  1. A.the ability of one interface or name to take many forms depending on the object or arguments
  2. B.a paradigm organizing software around objects that bundle data and the behavior acting on it
  3. C.a blueprint defining the attributes and methods that its objects will have
  4. D.a class is the abstract template, while an object is a concrete instance occupying memory at runtime

Answer + AI explanation with a free account

5. Which term means: "a blueprint defining the attributes and methods that its objects will have"?

Junior
  1. A.polymorphism
  2. B.message passing
  3. C.object-oriented programming
  4. D.class

Answer + AI explanation with a free account

6. Which statement is correct?

Junior
  1. A.class — the ability of one interface or name to take many forms depending on the object or arguments
  2. B.class — a blueprint defining the attributes and methods that its objects will have
  3. C.class — abstraction hides complexity at the design level, while encapsulation hides data by bundling and access control
  4. D.class — bundling data and methods in one unit and restricting direct external access to the internal state

Answer + AI explanation with a free account

7. What is object?

Junior
  1. A.a blueprint defining the attributes and methods that its objects will have
  2. B.exposing only essential features of an entity while hiding its complex implementation details
  3. C.a concrete instance of a class holding its own state in memory
  4. D.bundling data and methods in one unit and restricting direct external access to the internal state

Answer + AI explanation with a free account

8. Which term means: "a concrete instance of a class holding its own state in memory"?

Junior
  1. A.abstraction
  2. B.DRY principle
  3. C.object
  4. D.abstraction vs encapsulation

Answer + AI explanation with a free account

9. Which statement is correct?

Junior
  1. A.object — a field whose own copy belongs to each object created from a class
  2. B.object — a paradigm organizing software around objects that bundle data and the behavior acting on it
  3. C.object — a class is the abstract template, while an object is a concrete instance occupying memory at runtime
  4. D.object — a concrete instance of a class holding its own state in memory

Answer + AI explanation with a free account

10. What is encapsulation?

Junior
  1. A.bundling data and methods in one unit and restricting direct external access to the internal state
  2. B.objects interacting by invoking each other's methods rather than accessing fields directly
  3. C.a paradigm organizing software around objects that bundle data and the behavior acting on it
  4. D.a mechanism where a derived class acquires the attributes and behavior of a base class

Answer + AI explanation with a free account

11. Which term means: "bundling data and methods in one unit and restricting direct external access to the internal state"?

Junior
  1. A.encapsulation
  2. B.inheritance
  3. C.DRY principle
  4. D.message passing

Answer + AI explanation with a free account

12. Which statement is correct?

Junior
  1. A.encapsulation — exposing only essential features of an entity while hiding its complex implementation details
  2. B.encapsulation — the guideline 'do not repeat yourself', avoiding duplicated logic by factoring it into one place
  3. C.encapsulation — a concrete instance of a class holding its own state in memory
  4. D.encapsulation — bundling data and methods in one unit and restricting direct external access to the internal state

Answer + AI explanation with a free account

13. What is abstraction?

Junior
  1. A.exposing only essential features of an entity while hiding its complex implementation details
  2. B.a paradigm organizing software around objects that bundle data and the behavior acting on it
  3. C.the ability of one interface or name to take many forms depending on the object or arguments
  4. D.bundling data and methods in one unit and restricting direct external access to the internal state

Answer + AI explanation with a free account

14. Which term means: "exposing only essential features of an entity while hiding its complex implementation details"?

Junior
  1. A.polymorphism
  2. B.class vs object
  3. C.abstraction
  4. D.instance variable

Answer + AI explanation with a free account

15. Which statement is correct?

Junior
  1. A.abstraction — exposing only essential features of an entity while hiding its complex implementation details
  2. B.abstraction — a concrete instance of a class holding its own state in memory
  3. C.abstraction — a mechanism where a derived class acquires the attributes and behavior of a base class
  4. D.abstraction — bundling data and methods in one unit and restricting direct external access to the internal state

Answer + AI explanation with a free account

16. What is inheritance?

Junior
  1. A.a mechanism where a derived class acquires the attributes and behavior of a base class
  2. B.a blueprint defining the attributes and methods that its objects will have
  3. C.a concrete instance of a class holding its own state in memory
  4. D.the guideline 'do not repeat yourself', avoiding duplicated logic by factoring it into one place

Answer + AI explanation with a free account

17. Which term means: "a mechanism where a derived class acquires the attributes and behavior of a base class"?

Junior
  1. A.instance variable
  2. B.message passing
  3. C.DRY principle
  4. D.inheritance

Answer + AI explanation with a free account

18. Which statement is correct?

Junior
  1. A.inheritance — exposing only essential features of an entity while hiding its complex implementation details
  2. B.inheritance — a mechanism where a derived class acquires the attributes and behavior of a base class
  3. C.inheritance — bundling data and methods in one unit and restricting direct external access to the internal state
  4. D.inheritance — a concrete instance of a class holding its own state in memory

Answer + AI explanation with a free account

19. What is polymorphism?

Junior
  1. A.the guideline 'do not repeat yourself', avoiding duplicated logic by factoring it into one place
  2. B.the ability of one interface or name to take many forms depending on the object or arguments
  3. C.abstraction hides complexity at the design level, while encapsulation hides data by bundling and access control
  4. D.a field whose own copy belongs to each object created from a class

Answer + AI explanation with a free account

20. Which term means: "the ability of one interface or name to take many forms depending on the object or arguments"?

Junior
  1. A.instance variable
  2. B.DRY principle
  3. C.abstraction
  4. D.polymorphism

Answer + AI explanation with a free account

21. Which statement is correct?

Junior
  1. A.polymorphism — bundling data and methods in one unit and restricting direct external access to the internal state
  2. B.polymorphism — the ability of one interface or name to take many forms depending on the object or arguments
  3. C.polymorphism — a blueprint defining the attributes and methods that its objects will have
  4. D.polymorphism — a field whose own copy belongs to each object created from a class

Answer + AI explanation with a free account

22. What is abstraction vs encapsulation?

Mid
  1. A.a paradigm organizing software around objects that bundle data and the behavior acting on it
  2. B.a class is the abstract template, while an object is a concrete instance occupying memory at runtime
  3. C.objects interacting by invoking each other's methods rather than accessing fields directly
  4. D.abstraction hides complexity at the design level, while encapsulation hides data by bundling and access control

Answer + AI explanation with a free account

23. Which term means: "abstraction hides complexity at the design level, while encapsulation hides data by bundling and access control"?

Mid
  1. A.object
  2. B.abstraction vs encapsulation
  3. C.class vs object
  4. D.class

Answer + AI explanation with a free account

24. Which statement is correct?

Mid
  1. A.abstraction vs encapsulation — abstraction hides complexity at the design level, while encapsulation hides data by bundling and access control
  2. B.abstraction vs encapsulation — objects interacting by invoking each other's methods rather than accessing fields directly
  3. C.abstraction vs encapsulation — a mechanism where a derived class acquires the attributes and behavior of a base class
  4. D.abstraction vs encapsulation — the ability of one interface or name to take many forms depending on the object or arguments

Answer + AI explanation with a free account

25. What is class vs object?

Mid
  1. A.the ability of one interface or name to take many forms depending on the object or arguments
  2. B.a class is the abstract template, while an object is a concrete instance occupying memory at runtime
  3. C.a paradigm organizing software around objects that bundle data and the behavior acting on it
  4. D.a mechanism where a derived class acquires the attributes and behavior of a base class

Answer + AI explanation with a free account

26. Which term means: "a class is the abstract template, while an object is a concrete instance occupying memory at runtime"?

Mid
  1. A.abstraction
  2. B.class vs object
  3. C.object-oriented programming
  4. D.inheritance

Answer + AI explanation with a free account

27. Which statement is correct?

Mid
  1. A.class vs object — a field whose own copy belongs to each object created from a class
  2. B.class vs object — the guideline 'do not repeat yourself', avoiding duplicated logic by factoring it into one place
  3. C.class vs object — the ability of one interface or name to take many forms depending on the object or arguments
  4. D.class vs object — a class is the abstract template, while an object is a concrete instance occupying memory at runtime

Answer + AI explanation with a free account

28. What is message passing?

Mid
  1. A.a blueprint defining the attributes and methods that its objects will have
  2. B.the guideline 'do not repeat yourself', avoiding duplicated logic by factoring it into one place
  3. C.a mechanism where a derived class acquires the attributes and behavior of a base class
  4. D.objects interacting by invoking each other's methods rather than accessing fields directly

Answer + AI explanation with a free account

29. Which term means: "objects interacting by invoking each other's methods rather than accessing fields directly"?

Mid
  1. A.class vs object
  2. B.class
  3. C.message passing
  4. D.object

Answer + AI explanation with a free account

30. Which statement is correct?

Mid
  1. A.message passing — the ability of one interface or name to take many forms depending on the object or arguments
  2. B.message passing — a paradigm organizing software around objects that bundle data and the behavior acting on it
  3. C.message passing — objects interacting by invoking each other's methods rather than accessing fields directly
  4. D.message passing — exposing only essential features of an entity while hiding its complex implementation details

Answer + AI explanation with a free account

Showing 30 of 36 OOP · Principles questions — the full set, with answers, explanations and an AI tutor on every question, is inside.

Free to start

Answers, AI explanations, and a free readiness check

Sign up free to check your answers with explanations, ask the AI tutor anything on any question, and take the free 2-minute readiness check for a scored result. One full AI mock interview, scored like a real panel, is free when you sign up.

Practice OOP · Principles free
24,000+ questions & coding problemsSoftware & IT16,274 questionsGovernment jobs26 examsAptitudenew questions every timeAI practice interviewwith feedback65 topics to practiseMechanical1,149 questionsGATE ME9 papersEngineering Mathematics381 questions2-minute checkfreeDSA Problems1,422Civil1,005 questionsGATE CE9 papersCS Fundamentals1,209 questionsYour scores6 skillsSystem Design25Electrical / EEE1,047 questionsGATE EE9 papersRun your codeC++ · Java · PythonLow-Level Design144Electronics & Comm.975 questionsGATE EC9 papersAI help on every questionFull-Stack6,282Chemical1,005 questionsGATE CH9 papersAI whiteboardsystem designWork abroadEurope · remote · transfersESE ME1 paperGATE practice papers2019–2026ESE CE1 paperDate alertsbefore the last dateESE EE1 paperBehavioural courseHR round practiceESE ET1 paperResume optimizerProSSC JE ME1 paperApplication trackerSSC JE CE1 paperCompany-wise prepSSC JE EE1 paperRole roadmapsRRB JE1 subjectPriced in ₹UPI · cardsISRO SC1 paperGATE CS9 papersIBPS SO IT1 paperUGC NET CS1 paperSSC CGL26 papersIBPS PO26 papersRRB NTPC26 papersSSC CHSL26 papersIBPS Clerk26 papersSBI Clerk26 papersRRB Group D26 papersSSC CPO26 papersSSC GD26 papers