Java Basics

Question 1

What is the purpose of the main method in a Java program?

Answer 1

To execute the program

Question 2

Which method moves the cursor to the next line after printing?

Answer 2

println()

Question 3

What keyword is used to declare a constant in Java?

Answer 3

final

Question 4

Which of the following is a valid identifier in Java?
A) 1stVariable
B) variable-name
C) $myVariable
D) my variable

Answer 4

C) $myVariable

Question 5

What are the different primitive data types in Java?
A) int, float, String
B) int, double, boolean
C) char, String, Object
D) byte, String, boolean

Answer 5

B) int, double, boolean

Question 6

How do you declare a variable in Java?

Answer 6

int x;

Question 7

What is type casting in Java?

Answer 7

Converting one data type to another (e.g. int to double )

Question 8

How do you declare a constant in Java?

Answer 8

final int x = 10;

Question 9

What does the escape sequence \n do in Java?

Answer 9

Inserts a new line

Question 10

What is the main difference between System.out.print() and System.out.println()?

Answer 10

println() adds a new line, while print() does not

Question 11

Which of the following is a valid identifier in Java?
A) 1stVariable
B) first-variable
C) _firstVariable
D) first variable

Answer 11

C) _firstVariable

Question 12

What is the primary purpose of the printf statement in Java?

Answer 12

To display formatted output

Question 13

Which of the following is the correct syntax for the printf statement?

Answer 13

System.out.printf(format, item1, item2);

Question 14

What does the format specifier %d represent in a printf statement?

Answer 14

An integer

Question 15

Which of the following format specifiers would you use to display a floating-point number with two decimal places?
A) %f
B) %.2f
C) %d
D) %s

Answer 15

B) %.2f

Question 16

What will be the output of the following code?
System.out.printf(“Value: %5d”, 42);

Answer 16

Value: 42

Question 17

Which of the following is NOT a valid format specifier in the printf statement?
A) %s
B) %c
C) %b
D) %f

Answer 17

C) %b

Question 18

What does the format specifier %s represent in a printf statement?
A) A single character
B) A string
C) An integer
D) A boolean

Answer 18

B) A string

Question 19

what will correctly format a double value to three decimal places using printf?
12.34567

Answer 19

System.out.printf(“%.3f”, 12.34567);

Question 20

What is the purpose of the remainder operator (%) in Java?

Answer 20

To find the remainder after division

Question 21

Which of the following is a syntax error?
A) int x = 10;
B) System.out.println(“Hello World”)
C) if (x > 5 {
D) x = x + 1;

Answer 21

C) if (x > 5 {

Question 22

What type of error occurs when a program attempts to divide by zero?

Answer 22

Runtime Error

Question 23

Which of the following statements correctly checks if a number is even?
A) if (number % 2 = 0)
B) if (number % 2 == 0)
C) if (number / 2 == 0)
D) if (number & 2 == 0)

Answer 23

B) if (number % 2 == 0)

Question 24

What is a logic error?

Answer 24

An error that produces incorrect results despite the program running successfully

Question 25

Which method is used to read an integer input from the user using the Scanner class?

Answer 25

nextInt()

Question 26

Which of the following statements is true about logic errors?
A) They are detected by the compiler.
B) They cause the program to crash.
C) They produce incorrect output without crashing the program.
D) They are the easiest type of error to identify.

Answer 26

C) They produce incorrect output without crashing the program.

Question 27

common cause of syntax errors?

Answer 27

• Using the wrong variable type
• Forgetting to close a string with a quotation mark
• Incorrectly using operators

Question 28

What is the output of the following code if x is 10?
if (x = 5) {
System.out.println(“x is 5”);
}

Answer 28

A syntax error

Question 29

Which of the following statements correctly describes a runtime error?
A) It occurs when the code is written incorrectly.
B) It occurs when the program is running and encounters an unexpected condition.
C) It is always caused by a syntax error.
D) It can be fixed by simply recompiling the code.

Answer 29

It occurs when the program is running and encounters an unexpected condition.

Question 30

What type of error is caused by using a variable that has not been initialized?

Answer 30

Runtime Error