Java -Basics

#1. What is the correct extension for Java source files?

.jav

.java

.class

.js

#2. What is the output of a Java program compiled without errors?

.java file

.class file

.exe file

.txt file

#3. Which keyword is used to define a class in Java?

define

class

import

static

#4. What is the default value of a boolean in Java?

null

false

true

#5. Which of the following is not a Java keyword?

default

transient

null

super

#6. Which method is the entry point for a Java program?

execute()

run()

main()

start()

#7. Which data type is used to store decimal numbers in Java?

double

int

boolean

char

#8. What is the size of an int in Java?

32 bits

64 bits

16 bits

Depends on the system

#9. What is the correct way to declare an array in Java?

int array[];

int array[] = new int[5];

int[] array;

All of the above

#10. Which of these is not a primitive data type in Java?

String

char

boolean

int

#11. How do you declare a constant variable in Java?

Using const keyword

Using static keyword

Using immutable keyword

Using final keyword

#12. What is the correct syntax for a for loop in Java?

foreach (int i : 10)

loop (int i = 0; i < 10; i++)

for i in range(10)

for (int i = 0; i < 10; i++)

#13. What does JVM stand for?

Java Verification Machine

Java Virtual Manager

Java Virtual Machine

Java Vendor Module

#14. Which operator is used for string concatenation in Java?

#15. What is the default value of a reference variable in Java?

undefined

null

empty

#16. Which of these is a valid declaration of a char?

char c = c+c;

char c = 'c';

char c = c;

char c = "c";

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

extends

inherit

inherits

extend

#18. What is the purpose of the this keyword in Java?

Declares a static variable

Refers to the parent class

Defines a new object

Refers to the current object

#19. Which of these can be used to perform multiple inheritances in Java?

Abstract Classes

Enums

Interfaces

Classes

#20. What does the break keyword do in Java?

Returns from a method

Exits the loop or switch statement

Pauses the program

Exits the program

#21. What is the output of System.out.println(5 / 2);?

2.5

Error

#22. Which of the following is a checked exception in Java?

NullPointerException

IOException

ArrayIndexOutOfBoundsException

ArithmeticException

#23. What is the purpose of the finalize() method in Java?

It is used to declare constants.

It is used to close resources explicitly.

It is called by the garbage collector before destroying an object.

It is called at the end of a program.

#24. Which method is used to start a thread in Java?

run()

execute()

begin()

start()

#25. What is the base class of all classes in Java?

Root

Base

Object

Class

#26. Which of these is not an access modifier in Java?

private

protected

public

void

#27. Which keyword is used to declare a constant in Java?

const

final

static

immutable

#28. What does the super keyword refer to in Java?

A static variable in the class

A reference to a child class

The superclass of the current object

A method of the current object

#29. Which of these is the correct way to create an object in Java?

ClassName obj = new ClassName;

ClassName obj = new ClassName();

ClassName obj = ClassName();

ClassName obj();

#30. What is a Java package?

A folder for organizing files

A container for classes and sub-packages

A collection of classes

A library of predefined functions

#31. What does the static keyword indicate in Java?

The method cannot be overridden

The method is final

The variable or method belongs to the class rather than an instance

The method is synchronized

#32. Which of these is a wrapper class in Java?

double

Integer

int

float

#33. Which method is used to compare strings in Java?

C) ==

B) compareTo()

D) Both A and B

A) equals()

#34. Which of these is a marker interface in Java?

C) Comparable

A) Serializable

D) Both A and B

B) Cloneable

#35. What does the finally block do in Java?

Executes regardless of whether an exception occurs or not

Executes only if an exception occurs

None of the above

Executes only if no exception occurs

#36. What is the default value of a String variable in Java?

"" (empty string)

null

undefined

"" (space)

#37. What is polymorphism in Java?

Multiple classes with the same name

None of the above

The ability of a method to behave differently based on the object

Using multiple threads simultaneously

#38. Which of these is a reserved keyword in Java?

main

goto

null

friend

#39. What is the size of a long in Java?

4 bytes

16 bytes

System-dependent

8 bytes

#40. Which of the following is not an OOP concept in Java?

Polymorphism

Encapsulation

Compilation

Abstraction

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There are Multiple Choice Questions

Correct answers color: Green

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#1. What is the correct extension for Java source files?

#2. What is the output of a Java program compiled without errors?

#3. Which keyword is used to define a class in Java?

#4. What is the default value of a boolean in Java?

#5. Which of the following is not a Java keyword?

#6. Which method is the entry point for a Java program?

#7. Which data type is used to store decimal numbers in Java?

#8. What is the size of an int in Java?

#9. What is the correct way to declare an array in Java?

#10. Which of these is not a primitive data type in Java?

#11. How do you declare a constant variable in Java?

#12. What is the correct syntax for a for loop in Java?

#13. What does JVM stand for?

#14. Which operator is used for string concatenation in Java?

#15. What is the default value of a reference variable in Java?

#16. Which of these is a valid declaration of a char?

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

#18. What is the purpose of the this keyword in Java?

#19. Which of these can be used to perform multiple inheritances in Java?

#20. What does the break keyword do in Java?

#21. What is the output of System.out.println(5 / 2);?

#22. Which of the following is a checked exception in Java?

#23. What is the purpose of the finalize() method in Java?

#24. Which method is used to start a thread in Java?

#25. What is the base class of all classes in Java?

#26. Which of these is not an access modifier in Java?

#27. Which keyword is used to declare a constant in Java?

#28. What does the super keyword refer to in Java?

#29. Which of these is the correct way to create an object in Java?

#30. What is a Java package?

#31. What does the static keyword indicate in Java?

#32. Which of these is a wrapper class in Java?

#33. Which method is used to compare strings in Java?

#34. Which of these is a marker interface in Java?

#35. What does the finally block do in Java?

#36. What is the default value of a String variable in Java?

#37. What is polymorphism in Java?

#38. Which of these is a reserved keyword in Java?

#39. What is the size of a long in Java?

#40. Which of the following is not an OOP concept in Java?

Results

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