Java Objects and Classes MCQ

Java is an Object-Oriented Programming (OOP) language. At the heart of OOP in Java are two main concepts: objects and classes. Objects are instances of classes, and classes act as blueprints for objects. How well do you understand these foundational principles? Let’s find out with this quiz on Java Objects and Classes!

Each question is followed by the correct answer and an explanation to help reinforce your knowledge.

1. Which of the following is a correct definition of a class?

a) An instance of an object
b) A blueprint or prototype for creating objects
c) A method in Java
d) A package in Java

Answer:

b) A blueprint or prototype for creating objects

Explanation:

A class in Java is a blueprint or prototype from which individual objects are created.

2. What is an object in Java?

a) A reference to a class
b) A runtime entity
c) A method
d) An attribute

Answer:

b) A runtime entity

Explanation:

An object is a runtime entity, or in other words, a real-world entity, which is created based on a class.

3. Which keyword is used to create a new instance of a class?

a) new
b) this
c) instance
d) object

Answer:

a) new

Explanation:

The new keyword is used in Java to instantiate a new object of a class.

4. What do we mean by the “state” of an object?

a) Its behavior
b) The values assigned to its instance variables
c) Its methods
d) Its interface

Answer:

b) The values assigned to its instance variables

Explanation:

The state of an object refers to the values assigned to its instance variables at any given moment.

5. What are the main components of a class?

a) Attributes and Packages
b) Objects and References
c) Methods and Attributes
d) Constructors and Destructors

Answer:

c) Methods and Attributes

Explanation:

A class in Java mainly consists of attributes (variables) and methods (functions).

6. Which keyword is used to refer to the current instance of an object within a class?

a) object
b) this
c) self
d) class

Answer:

b) this

Explanation:

The this keyword in Java is used to refer to the current instance of an object within a class.

7. Which of these best describes “Encapsulation”?

a) Breaking a complex problem into simpler pieces
b) Wrapping up of data and methods into a single unit
c) Inheriting properties from a parent class
d) Implementing multiple interfaces

Answer:

b) Wrapping up of data and methods into a single unit

Explanation:

Encapsulation refers to the OOP principle where data (attributes) and methods are wrapped up together into a single unit (i.e., a class).

8. Which of these is NOT an advantage of using classes and objects in Java?

a) Improved performance
b) Modular structure
c) Reusability of code
d) Easy to manage and control access

Answer:

a) Improved performance

Explanation:

While OOP principles make code more organized, modular, and reusable, they do not inherently improve performance.

9. When a class inherits a property from another class, it is termed as…?

a) Encapsulation
b) Polymorphism
c) Inheritance
d) Instantiation

Answer:

c) Inheritance

Explanation:

Inheritance is an OOP principle where one class inherits properties and behaviors from another class.

I hope this quiz enriched your understanding of Java’s objects and classes. Whether you aced the quiz or learned something new, continue your journey into Java’s vast landscape. Every step takes you closer to mastering the language. Happy learning!

10. Can a class have multiple constructors?

a) Yes
b) No

Answer:

a) Yes

Explanation:

A class in Java can have multiple constructors, as long as they have different parameter lists. This is known as constructor overloading.

I hope this quiz enriched your understanding of Java’s objects and classes. Whether you aced the quiz or learned something new, continue your journey into Java’s vast landscape. Every step takes you closer to mastering the language. Happy learning!


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