OOPs Quiz - MCQ - Multiple Choice Questions and Answers

Welcome to our OOPs Quiz, a curated collection of Multiple Choice Questions (MCQs) designed to test and enhance your understanding of Object-Oriented Programming (OOP). OOP is a fundamental programming paradigm used in software development, emphasizing objects, classes, and the principles of encapsulation, inheritance, polymorphism, and abstraction. Whether you're a beginner eager to learn the basics or an experienced programmer looking to refresh your knowledge, this quiz offers a range of questions that cover the essential concepts of OOP.

Dive into the quiz to explore the intricacies of object-oriented languages like Java, C++, and Python. Each question is accompanied by detailed explanations, providing a valuable learning opportunity to understand not just the 'what' but the 'why' behind each answer. This quiz is an excellent way to prepare for interviews and exams or simply gauge your current understanding of OOP.

Get ready to challenge yourself and discover new aspects of object-oriented programming. Let's start the journey to mastering OOP with our comprehensive MCQ quiz!

1. What does OOP stand for?

a) Object-Oriented Programming

b) Only Object Programming

c) Oriented-Object Programming

d) Operations On Programs

Answer:

a) Object-Oriented Programming

Explanation:

OOP stands for Object-Oriented Programming, a programming paradigm based on the concept of "objects", which can contain data and code: data in the form of fields (often known as attributes or properties), and code, in the form of procedures (often known as methods).

2. Which of the following is a principle of OOP?

a) Inheritance

b) Compilation

c) Interpretation

d) Tokenization

Answer:

a) Inheritance

Explanation:

Inheritance is a fundamental principle of object-oriented programming that allows a class to inherit properties and methods from another class.

3. What is an object in OOP?

a) A function that performs a specific task

b) A variable that stores data

c) An instance of a class

d) A type of data structure

Answer:

c) An instance of a class

Explanation:

In object-oriented programming, an object is an instance of a class, which can contain both data and methods that perform operations on the data.

4. What is a class in OOP?

a) A specific data type

b) A blueprint for creating objects

c) A collection of data fields

d) A method that performs a certain action

Answer:

b) A blueprint for creating objects

Explanation:

A class in object-oriented programming is a blueprint or template from which individual objects are created. It defines the properties and behaviors that the created objects share.

5. What is the process of wrapping data and code into a single unit?

a) Inheritance

b) Encapsulation

c) Abstraction

d) Polymorphism

Answer:

b) Encapsulation

Explanation:

Encapsulation refers to bundling the data (attributes) and methods (functions) that operate on the data into a single unit or class.

6. How is a subclass related to a superclass in OOP?

a) A subclass is the same as a superclass

b) A subclass inherits methods and properties from a superclass

c) A subclass can only exist within a superclass

d) A subclass and superclass are unrelated

Answer:

b) A subclass inherits methods and properties from a superclass

Explanation:

In object-oriented programming, a subclass (or derived class) inherits methods and properties from a superclass (or base class), allowing for code reuse and extension of existing code.

7. What is the concept of abstraction in OOP?

a) Removing features from a class to simplify it

b) Hiding complex implementation details and showing only the necessary features of an object

c) Copying the behavior of another class

d) Converting real-world entities into classes

Answer:

b) Hiding complex implementation details and showing only the necessary features of an object

Explanation:

Abstraction in OOP involves hiding complex implementation details and exposing only essential features of an object or system, simplifying programming and enhancing security.

8. Which keyword is used to inherit a class in Java?

a) class

b) super

c) this

d) extends

Answer:

d) extends

Explanation:

In Java, the "extends" keyword is used for a class to inherit the properties and methods of another class.

9. Which concept of OOP allows the same function to behave differently based on the object?

a) Encapsulation

b) Abstraction

c) Inheritance

d) Polymorphism

Answer:

d) Polymorphism

Explanation:

Polymorphism is a concept in OOP that allows methods to do different things based on the object it is acting upon, enabling the same function name to be used for different types.

10. In OOP, what does the term "inheritance" refer to?

a) The process by which one class acquires the properties of another class

b) The ability to prevent changes to the implementation details of a class

c) The method of changing the value of a variable

d) The act of copying the behavior of a class

Answer:

a) The process by which one class acquires the properties of another class

Explanation:

Inheritance is a key feature of OOP that allows one class (the subclass or derived class) to inherit the attributes and behaviors (methods) of another class (the superclass or base class).

11. Which OOP concept involves wrapping data and methods into a single unit?

a) Encapsulation

b) Polymorphism

c) Inheritance

d) Composition

Answer:

a) Encapsulation

Explanation:

Encapsulation is the OOP concept of combining data (attributes) and methods (actions) into a single unit called class. It helps in hiding the internal state of the object from the outside world.

12. What is an abstract class in OOP?

a) A class that cannot be instantiated and is designed to be subclassed

b) A class that can only contain static methods

c) A class without any methods

d) A fully implemented class with no abstract methods

Answer:

a) A class that cannot be instantiated and is designed to be subclassed

Explanation:

An abstract class in OOP is a class that cannot be instantiated on its own and is intended to be extended by other classes. It can contain abstract methods (without implementations) as well as implemented methods.

13. What is the purpose of a constructor in an object-oriented programming language?

a) To destroy an instance of a class

b) To initialize an object when it is created

c) To declare variables

d) To perform cleanup operations before the program terminates

Answer:

b) To initialize an object when it is created

Explanation:

A constructor is a special method in an object-oriented programming language that is automatically called when an instance of a class is created. Its primary purpose is to initialize the new object.

14. Which principle of OOP suggests that only necessary information is displayed to the user?

a) Polymorphism

b) Encapsulation

c) Abstraction

d) Inheritance

Answer:

c) Abstraction

Explanation:

Abstraction is the principle of hiding the complex reality while exposing only the necessary parts. It simplifies the interface that is presented to the user, focusing on what an object does instead of how it does it.

15. What is the difference between an object and a class in OOP?

a) An object is a template, and a class is an instance of that template

b) An object and a class are the same things

c) A class is a blueprint for objects; an object is an instance of a class

d) A class defines a method, and an object defines attributes

Answer:

c) A class is a blueprint for objects; an object is an instance of a class

Explanation:

In OOP, a class is a blueprint or template that defines the attributes and methods that the object of this class will have. An object is an instance of a class, created with specific values for its attributes and with the ability to use its methods.

16. Which keyword is used to inherit a class in Java?

a) class

b) super

c) this

d) extends

Answer:

d) extends

Explanation:

In Java, the "extends" keyword is used for a class to inherit the properties and methods of another class.

17. What is an interface in OOP?

a) A way to make multiple copies of the same class

b) A tool used for debugging code

c) A template that describes a set of methods that a class must implement

d) A class that contains only private methods

Answer:

c) A template that describes a set of methods that a class must implement

Explanation:

An interface in OOP is a reference type that defines a set of methods that a class must implement. Interfaces specify what a class must do, but not how it does it.

18. In OOP, what is method overriding?

a) Changing the way a method works

b) Using a method from a parent class without modification

c) Creating a method with the same name and parameters in the subclass as in the parent class

d) Increasing the visibility of a method in a subclass

Answer:

c) Creating a method with the same name and parameters in the subclass as in the parent class

Explanation:

Method overriding in OOP occurs when a subclass provides a specific implementation of a method that is already defined in its parent class.

19. What is the significance of the "new" keyword in OOP?

a) It is used to delete objects

b) It declares static methods

c) It is used to create a new instance of a class

d) It overrides a method

Answer:

c) It is used to create a new instance of a class

Explanation:

The "new" keyword in OOP is used to create a new object or instance of a class, allocating memory for the object and initializing it.

20. Which of the following is not an OOP language?

a) Python

b) C++

c) HTML

d) Java

Answer:

c) HTML

Explanation:

HTML (HyperText Markup Language) is not an object-oriented programming language. It is a markup language used for creating and designing web pages.

21. In OOP, what is an attribute?

a) A function within a class

b) A class that is inherited from another class

c) A data member of a class

d) The name of a class

Answer:

c) A data member of a class

Explanation:

An attribute in OOP refers to a data member of a class. Attributes hold the data or state of an object, while methods define its behavior.

22. What is the purpose of getter and setter methods in OOP?

a) To define class variables

b) To manipulate object attributes safely

c) To delete object attributes

d) To declare static methods

Answer:

b) To manipulate object attributes safely

Explanation:

Getter and setter methods in OOP are used to safely access and update the private attributes of a class from outside the class.

23. What does the concept of composition in OOP refer to?

a) A function that combines two classes

b) Building new classes from existing ones

c) A class that contains instances of other classes as part of its state

d) The total number of classes in a program

Answer:

c) A class that contains instances of other classes as part of its state

Explanation:

Composition in OOP is a design principle where a class contains instances of other classes as part of its state. This represents a "has-a" relationship between objects.

24. What is "static" method in OOP?

a) A method that changes frequently

b) A method that can be called on an instance of a class

c) A method that belongs to the class rather than any object instance

d) A method that is called automatically when a program starts

Answer:

c) A method that belongs to the class rather than any object instance

Explanation:

A static method in OOP belongs to the class rather than any particular object instance. It can be called without creating an instance of the class.

25. What is method overloading?

a) Deleting a method from a superclass

b) Changing the return type of a method

c) Creating multiple methods in the same class with the same name but different parameters

d) Increasing the execution speed of a method

Answer:

c) Creating multiple methods in the same class with the same name but different parameters

Explanation:

Method overloading in OOP is a feature that allows a class to have more than one method having the same name, if their parameter lists are different.

26. What is the use of the "this" keyword in OOP?

a) To terminate programs

b) To refer to the current object in a method or constructor

c) To call a static method within the class

d) To declare variables

Answer:

b) To refer to the current object in a method or constructor

Explanation:

The "this" keyword is used in OOP to refer to the current object within a method or a constructor of the class it is used.

27. How do you define a constant in an OOP language like Java?

a) By using the 'var' keyword

b) By initializing a variable inside a method

c) By using the 'final' keyword

d) By declaring a variable without a value

Answer:

c) By using the 'final' keyword

Explanation:

In Java and some other OOP languages, the 'final' keyword is used to define a constant value. Once a variable is declared as 'final', its value cannot be modified.

28. What is the purpose of the "super" keyword in OOP?

a) To call a method in the parent class

b) To declare a variable as superior

c) To override a method in the child class

d) To indicate superior access permissions

Answer:

a) To call a method in the parent class

Explanation:

The "super" keyword in OOP is used within a subclass to call methods or constructors of the superclass from which the subclass is derived.