Master Object-Oriented Programming: Classes and Objects

Question 1

Which of the following is not a characteristic of object-oriented programming?

Accepted Answer

Use of global variables

Answer

Encapsulation

Answer

Inheritance

Answer

Modularity

Question 2

What is the primary purpose of a constructor in an object-oriented program?

Accepted Answer

To create new objects and initialize their properties

Answer

To define the behavior of objects

Answer

To manage object memory

Answer

To provide a way to access private members of the class

Question 3

Which term describes the ability for objects to have multiple forms and respond differently based on their type?

Accepted Answer

Polymorphism

Answer

Encapsulation

Answer

Inheritance

Answer

Abstraction

Question 4

Which of the following is a benefit of encapsulation?

Accepted Answer

Improved security and easier maintenance

Answer

Increased code reusability

Answer

Reduced memory usage

Answer

Faster program execution

Question 5

Which access modifier restricts access to class members within the same class and its subclasses?

Accepted Answer

Protected

Answer

Public

Answer

Private

Answer

Internal

Question 6

What is the term for deriving a new class from an existing class, inheriting its properties and methods?

Accepted Answer

Inheritance

Answer

Composition

Answer

Aggregation

Answer

Polymorphism

Question 7

What is the term for a method in a subclass that has the same name and signature as a method in its superclass?

Accepted Answer

Overriding method

Answer

Overloaded method

Answer

Virtual method

Answer

Redefined method

Question 8

Which design principle promotes loose coupling between classes, making them less dependent on each other?

Accepted Answer

Dependency Inversion

Answer

Interface Segregation

Answer

Single Responsibility

Answer

Open-Closed Principle

Question 9

Which type of polymorphism allows objects of different classes to respond to the same method call?

Accepted Answer

Runtime polymorphism

Answer

Compile-time polymorphism

Answer

Type polymorphism

Answer

Parametric polymorphism

Question 10

What is the main purpose of encapsulation in object-oriented programming?

Accepted Answer

To hide the implementation details of a class

Answer

To improve code readability

Answer

To enhance security

Answer

To ensure data integrity

Question 11

Which access modifier is used to restrict access to class members only within the class itself?

Accepted Answer

private

Answer

public

Answer

protected

Answer

default

Question 12

Which of the following is a key principle of inheritance?

Accepted Answer

Subclass inherits properties and methods from superclass

Answer

Superclass can access members of subclass

Answer

Multiple inheritance is always allowed

Answer

Interfaces cannot be inherited

Question 13

What is the primary benefit of using polymorphism in object-oriented programming?

Accepted Answer

Allows different objects to respond to the same message in different ways

Answer

Simplifies code maintenance

Answer

Improves code reusability

Answer

Increases execution speed

Question 14

Which of the following is not a visibility modifier in Java?

Accepted Answer

internal

Answer

public

Answer

private

Answer

protected

Question 15

What is the primary difference between a property and a field in object-oriented programming?

Accepted Answer

Properties provide a controlled interface to access and modify fields

Answer

Fields are private members of a class, while properties are public members

Answer

Properties are computed values, while fields store actual data

Answer

There is no difference between a property and a field

Question 16

What is the term for creating an instance of a class?

Accepted Answer

Instantiation

Answer

Encapsulation

Answer

Inheritance

Answer

Polymorphism

Question 17

Which term describes the ability of objects to exhibit different behaviors based on their class?

Accepted Answer

Polymorphism

Answer

Encapsulation

Answer

Inheritance

Answer

Abstraction

Question 18

Consider the following code excerpt:
class Shape {double area;}
class Rectangle extends Shape {double width, height;}
What is the relationship between the Shape and Rectangle classes?

Accepted Answer

Shape is the parent class and Rectangle is the child class

Answer

Rectangle is the parent class and Shape is the child class

Answer

Shape and Rectangle are independent classes

Answer

This code demonstrates invalid inheritance

Question 19

Which of the following is not an access modifier in Java?

Accepted Answer

internal

Answer

public

Answer

private

Answer

protected

Question 20

What is the process called when you create an instance of a class?

Accepted Answer

Instantiation

Answer

Initialization

Answer

Declaration

Answer

Allocation

Question 21

Which access modifier allows elements of a class to be accessed from outside the class?

Accepted Answer

public

Answer

private

Answer

protected

Answer

internal

Question 22

Describe the relationship between a superclass and its subclasses.

Accepted Answer

The superclass is a parent class, while the subclass is a child class.

Answer

The subclass is a parent class, while the superclass is a child class.

Answer

They have no relation to each other.

Answer

They are at the same level of hierarchy.

Question 23

Which of the following scenarios exemplifies polymorphism?

Accepted Answer

Calling the same method on different objects, even though they belong to different classes.

Answer

Creating a square and a circle, both of which have a getArea() method.

Answer

Using the same variable name to store different data types.

Answer

Overloading a method with different parameters.

Question 24

Explain the distinction between a class and an object.

Accepted Answer

A class is a blueprint, while an object is a specific instance of that blueprint.

Answer

An object is a blueprint, while a class is an instance of that blueprint.

Answer

They are essentially the same thing.

Answer

They have no connection to each other.

Question 25

What is the primary purpose of a constructor?

Accepted Answer

To initialize an object's state

Answer

To terminate an object's state

Answer

To compare two objects

Answer

To create a new object

Question 26

Which of the following is not a recognized type of inheritance?

Accepted Answer

Polymorphism

Answer

Single inheritance

Answer

Multiple inheritance

Answer

Hybrid inheritance

Question 27

Which of the following is NOT a mechanism for achieving polymorphism in Java?

Accepted Answer

Multiple inheritance

Answer

Method overloading

Answer

Method overriding

Answer

Interface implementation

Question 28

What is the primary purpose of encapsulation in OOP?

Accepted Answer

To hide data and implementation details

Answer

To improve code readability

Answer

To enhance performance

Answer

To facilitate code reuse

Question 29

What is the primary purpose of the 'this' keyword in Java?

Accepted Answer

To refer to the current object

Answer

To access superclass methods

Answer

To invoke constructors

Answer

To identify the current class

Question 30

Which of the following principles is enforced by the Java Virtual Machine?

Accepted Answer

Type safety

Answer

Encapsulation

Answer

Inheritance

Answer

Polymorphism

Question 31

How does a class differ from an object?

Accepted Answer

A class is a blueprint, while an object is a specific instance of it

Answer

An object is a blueprint, while a class is a specific instance of it

Answer

A class and an object are the same thing

Answer

An object can exist without a class, but a class cannot exist without an object

Question 32

Which of the following access modifiers is most restrictive?

Accepted Answer

private

Answer

public

Answer

protected

Answer

default

Question 33

In object-oriented programming, information hiding refers to:

Accepted Answer

Data within an object is encapsulated, limiting external access

Answer

Unrestricted access to data and methods within an object

Answer

Inherited classes have unrestricted access to all data in the parent class

Answer

Objects are independent entities with no shared data

Question 34

Which of the following is a potential disadvantage of object-oriented programming?

Accepted Answer

Increased Complexity

Answer

Reduced Reusability

Answer

Enhanced Maintainability

Question 35

In Java, which mechanism is primarily used to enforce encapsulation?

Accepted Answer

Access modifiers

Answer

Static methods

Answer

Final classes

Question 36

In object-oriented programming, what is the main purpose of abstraction?

Accepted Answer

To identify an object's essential features while hiding implementation details

Answer

To enable classes to inherit traits from other classes

Answer

To allow for the creation of multiple instances of a class

Answer

To define a set of behaviors that a class must implement using interfaces

Question 37

What is the process of creating a new object from an existing class called?

Accepted Answer

Instantiation: Creating an instance of a class, allocating memory for it, and initializing its state

Answer

Polymorphism: Allowing objects to respond to the same message in different ways

Answer

Inheritance: Creating a new class based on an existing class

Answer

Abstraction: Hiding the implementation details of an object

Question 38

What is the role of a constructor in OOP?

Accepted Answer

To initialize the state of a newly created object

Answer

To handle exceptions that occur within an object

Answer

To define the behavior of an object

Answer

To create new objects

Question 39

What is the difference between a class and an object?

Accepted Answer

A class is a blueprint or template, while an object is a specific instance of that class

Answer

A class is an object, while an object is a class

Answer

A class is a variable, while an object is a value

Question 40

Which of the following is an example of polymorphism?

Accepted Answer

Overriding a method in a subclass to provide a different implementation

Answer

Defining a class with multiple constructors

Answer

Creating a new object from a class

Answer

Using an interface to define a contract

Question 41

Which of the following is not a feature of an object-oriented programming (OOP) approach?

Accepted Answer

Emphasis on functions rather than data structures

Answer

Inheritance and polymorphism

Answer

Abstraction and encapsulation

Answer

Modularity and reusability

Question 42

Encapsulation in OOP primarily aims to:

Accepted Answer

Protect an object's internal state and behavior from unauthorized access.

Answer

Enhance code readability and maintenance.

Answer

Promote code reusability and extensibility.

Question 43

The fundamental difference between a class and an object in OOP is:

Accepted Answer

A class is a blueprint or template for creating objects, while an object is an instance of a class with a unique identity and state.

Answer

A class contains only methods, while an object contains both methods and data.

Answer

A class is intangible, while an object is tangible.

Answer

A class is static, while an object is dynamic.

Question 44

Which of the following best exemplifies polymorphism in OOP?

Accepted Answer

The ability for objects of different classes to respond to the same method call in a manner specific to their class.

Answer

The assignment of different data types to a single variable.

Answer

The ability to create objects with different sets of attributes.

Question 45

The primary purpose of a constructor in OOP is to:

Accepted Answer

Initialize the state of an object when it is created.

Answer

Destroy an object when it is no longer needed.

Answer

Enforce access restrictions on an object's members.

Question 46

In OOP, a static method is characterized by:

Accepted Answer

Being associated with the class rather than a specific object.

Answer

Being overridden in derived classes.

Answer

Requiring an object to be created before it can be called.

Answer

Being able to access non-static members of the class.

Question 47

The main purpose of an interface in OOP is to:

Accepted Answer

Define a set of methods that classes must implement without providing an implementation.

Answer

Enforce inheritance between unrelated classes.

Answer

Provide a default implementation for a set of methods.

Answer

Restrict access to certain members of a class.