Object-Oriented Design Principles – MCQs

1. : What does the principle of encapsulation promote?
(A) Data sharing
(B) Global variables
(C) Data hiding
(D) Multiple inheritance

2. : What is the goal of the Single Responsibility Principle (SRP)?
(A) One function per class
(B) One method should handle all tasks
(C) A class should have only one reason to change
(D) A class should only inherit once

3. : Which principle emphasizes depending on abstractions rather than concrete classes?
(A) Liskov Substitution Principle
(B) Dependency Inversion Principle
(C) Interface Segregation Principle
(D) Single Responsibility Principle

4. : What is the core idea of the Open-Closed Principle?
(A) A class should be closed to new features
(B) A class should not be modified
(C) A class should be open for extension but closed for modification
(D) A class should only contain one method

5. : Which design principle is violated when subclasses override base class methods incorrectly?
(A) Single Responsibility
(B) Liskov Substitution
(C) Dependency Inversion
(D) Interface Segregation

6. : What is favored in object-oriented design according to SOLID principles?
(A) Procedural programming
(B) Inheritance over composition
(C) Composition over inheritance
(D) Use of global variables

7. : What is cohesion in object-oriented design?
(A) Degree of dependency between classes
(B) Number of child classes
(C) Degree to which elements of a class belong together
(D) Use of multiple inheritance

8. : What does the Interface Segregation Principle suggest?
(A) One interface for all needs
(B) Large interfaces are better
(C) Use many specific interfaces rather than one general-purpose interface
(D) Avoid using interfaces

9. : Which principle helps to reduce tight coupling in OOP?
(A) Inheritance
(B) Polymorphism
(C) Dependency Inversion
(D) Static binding

10. : The principle “Favor object composition over class inheritance” helps in:
(A) Reducing class size
(B) Increasing reusability and flexibility
(C) Eliminating interfaces
(D) Avoiding encapsulation

11. : What does low coupling mean in OOP?
(A) Classes are tightly dependent on each other
(B) Classes are highly independent
(C) Classes are merged into one
(D) Classes cannot use inheritance

12. : Which of the following promotes reusability in OOP?
(A) Encapsulation
(B) Coupling
(C) Inheritance
(D) Static variables

13. : What is the primary advantage of high cohesion?
(A) Code duplication
(B) Ease of testing and maintenance
(C) Complex code
(D) Difficult debugging

14. : What is the concept of polymorphism related to?
(A) Overloading only
(B) Inheritance only
(C) Same interface, different implementations
(D) Same name for all methods

15. : Which principle is directly violated by using one class for too many unrelated responsibilities?
(A) Open-Closed
(B) Liskov Substitution
(C) Single Responsibility
(D) Interface Segregation

16. : Which of the following is NOT a SOLID principle?
(A) Single Responsibility Principle
(B) Open-Closed Principle
(C) Static Object Principle
(D) Interface Segregation Principle

17. : What is a design pattern in object-oriented design?
(A) Syntax rule
(B) General repeatable solution to a design problem
(C) Specific class implementation
(D) Language-specific feature

18. : Which of the following helps in achieving polymorphism?
(A) Private variables
(B) Inheritance and interfaces
(C) Constructors
(D) Static methods

19. : Which term is used for hiding internal object details from the outside world?
(A) Inheritance
(B) Polymorphism
(C) Encapsulation
(D) Abstraction

20. : Which of the following is an example of abstraction?
(A) Accessing object internals directly
(B) Using an ATM interface without knowing its internal logic
(C) Modifying all private variables
(D) Creating global variables

21. : What does tight coupling between classes indicate?
(A) Better design
(B) Reusability
(C) High dependency
(D) Data hiding

22. : What should be avoided to maintain loose coupling?
(A) Private members
(B) Abstract classes
(C) Direct instantiation of dependent classes
(D) Using virtual functions

23. : What helps ensure code extensibility without modification?
(A) Encapsulation
(B) Inheritance
(C) Open-Closed Principle
(D) Coupling

24. : Why is abstraction important in OOD?
(A) It complicates class design
(B) It hides complexity
(C) It promotes global access
(D) It reduces code flexibility

25. : What does the term “design principle” refer to?
(A) Syntax of a programming language
(B) Compiler rules
(C) Best practices for building scalable software
(D) Low-level logic

26. : Which principle is beneficial in preventing changes in one class from affecting others?
(A) Polymorphism
(B) Inheritance
(C) Low coupling
(D) Static typing

27. : How is abstraction different from encapsulation?
(A) Abstraction focuses on hiding data; encapsulation hides implementation
(B) Abstraction hides complexity; encapsulation hides data
(C) Abstraction uses private members; encapsulation uses public ones
(D) They are the same

28. : Which of the following is the foundation of object-oriented design?
(A) Structured programming
(B) Procedural logic
(C) Objects and Classes
(D) Global variables

29. : What does the term “modularity” mean in OOD?
(A) Using fewer classes
(B) Designing software in separate, interchangeable components
(C) Writing all code in a single file
(D) Avoiding use of interfaces

30. : Why is the SOLID principle set important in OOD?
(A) It simplifies syntax
(B) It enhances debugging
(C) It provides guidelines for maintainable and scalable code
(D) It increases inheritance