Creating Classes in Object-Oriented Programming: A Comprehensive Guide

Question 1

Which access modifier is invalid in Java?

Accepted Answer

internal

Answer

public

Answer

protected

Answer

private

Question 2

Which of the following syntaxes is correct to declare a private instance variable 'age' in Java?

Accepted Answer

private int age;

Answer

int age;

Answer

public int age;

Answer

protected int age;

Question 3

Which of the following data types is NOT supported as a member variable in Java?

Accepted Answer

array

Answer

int

Answer

double

Answer

boolean

Question 4

Which access modifier allows a member variable to be accessed outside the class but only within subclasses?

Accepted Answer

protected

Answer

public

Answer

private

Answer

default

Question 5

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

Accepted Answer

To refer to the current object

Answer

To refer to the superclass of the current object

Answer

To create a new instance of the current class

Answer

To access static members of the current class

Question 6

Which syntax is correct for creating an object of class 'ClassName' in Java?

Accepted Answer

ClassName objectName = new ClassName();

Answer

ClassName objectName;

Answer

objectName = new ClassName();

Answer

new ClassName(objectName);

Question 7

Which of the following is NOT a fundamental principle of object-oriented programming?

Accepted Answer

Recursion

Answer

Encapsulation

Answer

Inheritance

Answer

Polymorphism

Question 8

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

Accepted Answer

private

Answer

public

Answer

protected

Answer

internal

Question 9

What is the primary purpose of a constructor in a class?

Accepted Answer

To initialize the state of an object

Answer

To define the behavior of the class

Answer

To provide access to private members

Answer

To handle exceptions

Question 10

Which of the following is NOT considered a core principle of object-oriented programming?

Accepted Answer

Iteration

Answer

Encapsulation

Answer

Polymorphism

Answer

Inheritance

Question 11

What is the primary purpose of a static method in a class?

Accepted Answer

To operate on class-level data

Answer

To access instance-specific data

Answer

To provide access to private members

Answer

To handle exceptions

Question 12

Which of the following represents a valid example of inheritance?

Accepted Answer

class Child extends Parent { }

Answer

class Parent extends Child { }

Answer

class Child implements Parent { }

Answer

class Parent implements Child { }

Question 13

What is the primary role of an interface in object-oriented programming?

Accepted Answer

To define a contract that classes must implement

Answer

To provide a blueprint for implementing classes

Answer

To handle exceptions

Answer

To access private members

Question 14

In Object-Oriented Programming, which of the following is NOT considered a member of a class?

Accepted Answer

Object

Answer

Method

Answer

Variable

Answer

Constructor

Question 15

In Java, which access modifier allows a method or variable to be accessed outside its class?

Accepted Answer

public

Answer

secret

Answer

internal

Question 16

Which of the following is the correct syntax to define a class in Java?

Accepted Answer

public class ClassName { [class body] }

Answer

ClassName { [class body] }

Answer

class { [class body] } ClassName

Answer

ClassName class { [class body] }

Question 17

Which of the following access modifiers is not available in Java?

Accepted Answer

internal

Answer

public

Answer

private

Answer

protected

Question 18

Which code snippet correctly creates an instance of the 'Person' class?

Accepted Answer

Person person = new Person();

Answer

Person.new();

Answer

Person person;

Answer

new Person();

Question 19

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

Accepted Answer

To refer to the current object within a class.

Answer

To call the constructor of the current class.

Answer

To access static members of the current class.

Answer

To pass the current object as an argument to another method.

Question 20

What is the primary purpose of a constructor in a class?

Accepted Answer

To initialize the state of an object when it is created.

Answer

To define the behavior of an object.

Answer

To provide documentation for the class.

Answer

To create multiple instances of a class.

Question 21

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

Accepted Answer

Imperative execution

Answer

Encapsulation

Answer

Inheritance

Answer

Abstraction

Question 22

What is the key difference between an abstract class and an interface in Java?

Accepted Answer

Abstract classes can have both abstract and concrete methods, while interfaces can only have abstract methods.

Answer

Interfaces can be implemented by classes, while abstract classes cannot.

Answer

Abstract classes can be instantiated, while interfaces cannot.

Answer

There is no difference between abstract classes and interfaces in Java.

Question 23

What primary purpose do access modifiers serve in Java classes?

Accepted Answer

Regulate access to class components

Answer

Indicate the data type of class components

Answer

Enhance code readability

Answer

Prevent class inheritance

Question 24

Provide an example of encapsulation in Java.

Accepted Answer

Declaring class members private and accessing them via getter and setter methods

Answer

Establishing a class hierarchy through inheritance

Answer

Defining a contract for a class using interfaces

Answer

Providing multiple method implementations through overloading

Question 25

Which Java syntax demonstrates valid inheritance?

Accepted Answer

class Child extends Parent {}

Answer

class Parent implements Child {}

Answer

class Parent has-a Child {}

Answer

class Child is-a Parent {}

Question 26

What is the primary purpose of interfaces in Object-Oriented Programming?

Accepted Answer

Defining contracts that classes must fulfill

Answer

Enabling multiple inheritance

Answer

Establishing class hierarchies

Answer

Implementing polymorphism

Question 27

In Object-Oriented Programming (OOP), encapsulation provides several advantages. Which of the following best describes a key benefit of encapsulation?

Accepted Answer

Increased code reusability through controlled access to data and methods

Answer

Unrestricted access to data for enhanced visibility

Answer

Improved code readability without data protection

Question 28

Which syntax is used to declare a class in Java?

Accepted Answer

public class <class_name> {}

Answer

class <class_name> {}

Answer

class public <class_name> {}

Answer

public <class_name> class {}

Question 29

What is the primary purpose of access modifiers in a class?

Accepted Answer

To control the visibility of class members (fields and methods).

Answer

To improve code readability and organization.

Answer

To prevent accidental modifications of class data.

Answer

To enforce object-oriented principles.

Question 30

Which of the following is NOT a valid data type for a member variable in Java?

Accepted Answer

customType

Answer

int

Answer

boolean

Answer

String

Question 31

Which access modifier restricts a class member's visibility to the class itself?

Accepted Answer

private

Answer

public

Answer

protected

Answer

default

Question 32

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

Accepted Answer

To refer to the current object within the class.

Answer

To access static members of the class.

Answer

To pass the current object as an argument to another method.

Answer

To create a new instance of the class.

Question 33

Which of the following is an example of encapsulation in Object-Oriented Programming?

Accepted Answer

Creating a class with private member variables and public getter and setter methods.

Answer

Using inheritance to create a hierarchy of classes.

Answer

Implementing polymorphism through method overriding.

Answer

Declaring a class as final to prevent inheritance.

Question 34

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

Accepted Answer

Procedural Abstraction

Answer

Encapsulation

Answer

Inheritance

Answer

Aggregation

Question 35

What is the term used to describe the process of creating a new object in Java?

Accepted Answer

Instantiation

Answer

Initialization

Answer

Composition

Answer

Polymorphism

Question 36

Which of the following is the correct syntax to create a public class named "ExampleClass" in Java?

Accepted Answer

public class ExampleClass

Answer

public ExampleClass { }

Answer

ExampleClass { }

Answer

ExampleClass

Question 37

What is the primary purpose of an access modifier used with class members (e.g., fields, methods)?

Accepted Answer

To specify the visibility and accessibility of those members

Answer

To define the behavior of the class

Answer

To declare the types of the class members

Answer

To create instances of the class

Question 38

What is the fundamental distinction between a class and an object in Object-Oriented Programming?

Accepted Answer

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

Answer

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

Answer

A class and an object are essentially the same concept

Answer

An object is a template for a class

Question 39

Which of the following is NOT a potential benefit of using classes in programming?

Accepted Answer

Enhanced code redundancy

Answer

Increased code reusability

Answer

Improved program organization

Answer

Simplified program maintenance

Question 40

What is the primary role of a constructor in a Java class?

Accepted Answer

To initialize instance variables and perform initial setup for newly created objects

Answer

To define the overall behavior and functionality of the class

Answer

To create new instances of the class

Answer

To manage the access permissions of class members

Question 41

Which of the following code snippets correctly creates a new instance of the "ExampleClass" class in Java?

Accepted Answer

ExampleClass myObject = new ExampleClass();

Answer

ExampleClass myObject;

Answer

new ExampleClass myObject;

Answer

ExampleClass.new myObject;

Question 42

In Java, what is the key difference between the "public" and "protected" access modifiers?

Accepted Answer

Public members are accessible from anywhere, while protected members are only accessible within the class and subclasses

Answer

Public members are only accessible within the class and subclasses, while protected members are accessible from anywhere

Question 43

In Java, what is the primary purpose of a method within a class?

Accepted Answer

To define specific behaviors and actions that can be performed on objects of that class

Answer

To store data and information related to the class

Answer

To create new instances of the class

Answer

To control access to other class members

Question 44

In object-oriented programming, which of the following is a potential drawback of using inheritance?

Accepted Answer

Increased code complexity

Answer

Improved code maintainability

Answer

Enhanced code reusability

Question 45

What is the correct way to define a class in Java?

Accepted Answer

public class ClassName {}

Answer

class ClassName {} (without public access modifier)

Answer

{ } ClassName (inverted syntax)

Answer

ClassName class {} (incorrect order of keywords)

Question 46

Which of the following is a primary purpose of access modifiers?

Accepted Answer

To restrict access to class members based on their scope

Answer

To define the type of class

Answer

To specify the inheritance relationships

Answer

To declare class variables

Question 47

Which access modifier is used to restrict access within the same package only?

Accepted Answer

default

Answer

protected (incorrect as it allows access to subclasses outside the package)

Answer

public (incorrect as it allows wider access)

Answer

private (incorrect as it restricts access within the class only)

Question 48

What is the main role of member variables in a class?

Accepted Answer

To store instance-specific data associated with objects of that class

Answer

To control access to class methods

Answer

To specify the relationships between classes

Answer

To define the behavior of a class

Question 49

What is the fundamental difference between a class and an object?

Accepted Answer

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

Answer

A class is concrete, while an object is abstract (incorrect)

Answer

A class is an object, and an object is a class (incorrect)

Question 50

Which of the following is a key advantage of using classes in object-oriented programming?

Accepted Answer

Code reusability and better organization through encapsulation

Answer

Increased code complexity

Answer

Reduced performance

Answer

None of the above

Question 51

What keyword is used in Java to create an instance of a class?

Accepted Answer

new

Answer

create

Answer

initialize

Answer

instance

Question 52

Which of the following options correctly shows how to access a member variable of an object in Java?

Accepted Answer

object.variableName

Answer

ClassName.variableName

Answer

object->variableName

Answer

variableName.object