
Practice 100 Java Basic Programming Questions
Q1. Write a Java program to print "Hello, World!".
Input: No input
Expected Output:
Hello, World!
Q2. Write a Java program to print the sum of two numbers.
Input:
Enter first number: 5
Enter second number: 3
Expected Output:
Sum = 8
Q3. Write a Java program to swap two numbers without using a third variable.
Input:
Enter first number: 4
Enter second number: 7
Expected Output:
After swapping:
First number = 7
Second number = 4
Q4. Write a Java program to find the largest of two numbers.
Input:
Enter first number: 12
Enter second number: 8
Expected Output:
Largest number = 12
Q5. Write a Java program to check whether a number is even or odd.
Input:
Enter a number: 11
Expected Output:
11 is an odd number.
Q6. Write a Java program to calculate the area of a rectangle.
Input:
Enter length: 5
Enter width: 6
Expected Output:
Area of rectangle = 30
Q7. Write a Java program to calculate the area of a circle.
Input:
Enter radius: 7
Expected Output:
Area of circle = 153.93804
Q8. Write a Java program to print the multiplication table of a number.
Input:
Enter a number: 3
Expected Output:
3 x 1 = 3
3 x 2 = 6
3 x 3 = 9
...
3 x 10 = 30
Q9. Write a Java program to convert Celsius to Fahrenheit.
Input:
Enter temperature in Celsius: 25
Expected Output:
Temperature in Fahrenheit: 77.0
Q10. Write a Java program to reverse a string.
Input:
Enter a string: Hello
Expected Output:
Reversed string: olleH
Q11. Write a Java program to find the sum of digits of a number.
Input:
Enter a number: 123
Expected Output:
Sum of digits = 6
Q12. Write a Java program to check if a number is positive or negative.
Input:
Enter a number: -7
Expected Output:
The number is negative.
Q13. Write a Java program to check whether a character is a vowel or consonant.
Input:
Enter a character: a
Expected Output:
The character 'a' is a vowel.
Q14. Write a Java program to find the factorial of a number.
Input:
Enter a number: 5
Expected Output:
Factorial of 5 = 120
Q15. Write a Java program to check whether a number is prime.
Input:
Enter a number: 7
Expected Output:
7 is a prime number.
Q16. Write a Java program to print Fibonacci series up to N terms.
Input:
Enter the number of terms: 5
Expected Output:
Fibonacci series: 0, 1, 1, 2, 3
Q17. Write a Java program to count the number of digits in a number.
Input:
Enter a number: 45678
Expected Output:
Number of digits = 5
Q18. Write a Java program to find the greatest of three numbers.
Input:
Enter three numbers: 5 9 3
Expected Output:
The greatest number is 9.
Q19. Write a Java program to check if a number is palindrome.
Input:
Enter a number: 121
Expected Output:
121 is a palindrome.
Q20. Write a Java program to calculate the sum of N natural numbers.
Input:
Enter N: 10
Expected Output:
Sum = 55
Q21. Write a Java program to find the average of N numbers.
Input:
Enter the count of numbers: 4
Enter numbers: 5 10 15 20
Expected Output:
Average = 12.5
Q22. Write a Java program to find the GCD of two numbers.
Input:
Enter two numbers: 56 98
Expected Output:
GCD = 14
Q23. Write a Java program to calculate the simple interest.
Input:
Enter principal: 1000
Enter rate: 5
Enter time: 2
Expected Output:
Simple Interest = 100.0
Q24. Write a Java program to check whether a number is divisible by 5 and 11.
Input:
Enter a number: 55
Expected Output:
55 is divisible by both 5 and 11.
Q25. Write a Java program to convert kilometers to miles.
Input:
Enter distance in kilometers: 5
Expected Output:
Distance in miles: 3.106855
Q26. Write a Java program to print a pattern of stars.
Input:
Enter the number of rows: 4
Expected Output:
*
**
***
****
Q27. Write a Java program to calculate the power of a number using a loop.
Input:
Enter base: 2
Enter exponent: 3
Expected Output:
Result = 8
Q28. Write a Java program to find the largest and smallest numbers in an array.
Input:
Enter array elements: 2 8 1 6 3
Expected Output:
Largest number = 8
Smallest number = 1
Q29. Write a Java program to calculate the compound interest.
Input:
Enter principal: 1000
Enter rate: 5
Enter time: 2
Enter number of times interest applied per time period: 4
Expected Output:
Compound Interest = 1040.60401
Q30. Write a Java program to print ASCII value of a character.
Input:
Enter a character: A
Expected Output:
ASCII value of A = 65
Q31. Write a Java program to convert a decimal number to binary.
Input:
Enter a decimal number: 10
Expected Output:
Binary representation = 1010
Q32. Write a Java program to find the second largest number in an array.
Input:
Enter array elements: 5 3 9 1 6
Expected Output:
Second largest number = 6
Q33. Write a Java program to remove vowels from a string.
Input:
Enter a string: Programming
Expected Output:
String after removing vowels: Prgrmmng
Q34. Write a Java program to count the frequency of characters in a string.
Input:
Enter a string: apple
Expected Output:
Frequency of a: 1
Frequency of p: 2
Frequency of l: 1
Frequency of e: 1
Q35. Write a Java program to calculate the sum of elements in an array.
Input:
Enter array elements: 1 2 3 4 5
Expected Output:
Sum of array elements = 15
Q36. Write a Java program to reverse a number.
Input:
Enter a number: 1234
Expected Output:
Reversed number = 4321
Q37. Write a Java program to find the length of a string without using the built-in function.
Input:
Enter a string: Hello
Expected Output:
Length of the string = 5
Q38. Write a Java program to find the LCM of two numbers.
Input:
Enter two numbers: 12 15
Expected Output:
LCM = 60
Q39. Write a Java program to find the sum of elements on the diagonal of a matrix.
Input:
Enter matrix elements:
1 2 3
4 5 6
7 8 9
Expected Output:
Sum of diagonal elements = 15
Q40. Write a Java program to find the transpose of a matrix.
Input:
Enter matrix elements:
1 2 3
4 5 6
Expected Output:
Transpose:
1 4
2 5
3 6
Q41. Write a Java program to check if a string is a palindrome.
Input:
Enter a string: madam
Expected Output:
The string is a palindrome.
Q42. Write a Java program to count the number of vowels and consonants in a string.
Input:
Enter a string: Java
Expected Output:
Vowels: 2
Consonants: 2
Q43. Write a Java program to find the sum of even and odd numbers in an array.
Input:
Enter array elements: 1 2 3 4 5
Expected Output:
Sum of even numbers = 6
Sum of odd numbers = 9
Q44. Write a Java program to calculate the percentage of marks.
Input:
Enter marks in 5 subjects: 80 90 70 85 95
Expected Output:
Percentage = 84.0
Q45. Write a Java program to check whether a number is a perfect number.
Input:
Enter a number: 28
Expected Output:
28 is a perfect number.
Q46. Write a Java program to check whether a number is an Armstrong number.
Input:
Enter a number: 153
Expected Output:
153 is an Armstrong number.
Q47. Write a Java program to print all prime numbers between two intervals.
Input:
Enter start: 10
Enter end: 20
Expected Output:
Prime numbers: 11 13 17 19
Q48. Write a Java program to check whether a number is a palindrome.
Input:
Enter a number: 121
Expected Output:
121 is a palindrome number.
Q49. Write a Java program to find the square root of a number.
Input:
Enter a number: 16
Expected Output:
Square root = 4.0
Q50. Write a Java program to find the cube of a number.
Input:
Enter a number: 3
Expected Output:
Cube = 27
Q51. Write a Java program to check if a year is a leap year.
Input:
Enter a year: 2020
Expected Output:
2020 is a leap year.
Q52. Write a Java program to find the largest and smallest digits in a number.
Input:
Enter a number: 42593
Expected Output:
Largest digit = 9
Smallest digit = 2
Q53. Write a Java program to sort an array in ascending order.
Input:
Enter array elements: 5 3 8 6 1
Expected Output:
Sorted array: 1 3 5 6 8
Q54. Write a Java program to calculate the factorial of a number using recursion.
Input:
Enter a number: 4
Expected Output:
Factorial = 24
Q55. Write a Java program to calculate the product of digits of a number.
Input:
Enter a number: 234
Expected Output:
Product of digits = 24
Q56. Write a Java program to count the number of uppercase and lowercase letters in a string.
Input:
Enter a string: JaVa
Expected Output:
Uppercase letters: 2
Lowercase letters: 2
Q57. Write a Java program to reverse an array.
Input:
Enter array elements: 1 2 3 4 5
Expected Output:
Reversed array: 5 4 3 2 1
Q58. Write a Java program to calculate the sum of the main and secondary diagonal elements of a matrix.
Input:
Enter matrix elements:
1 2 3
4 5 6
7 8 9
Expected Output:
Main diagonal sum = 15
Secondary diagonal sum = 15
Q59. Write a Java program to merge two arrays.
Input:
Array 1: 1 2 3
Array 2: 4 5 6
Expected Output:
Merged array: 1 2 3 4 5 6
Q60. Write a Java program to convert a character to uppercase.
Input:
Enter a character: a
Expected Output:
Uppercase: A
Q61. Write a Java program to convert a string to uppercase.
Input:
Enter a string: hello
Expected Output:
Uppercase: HELLO
Q62. Write a Java program to find the first and last digit of a number.
Input:
Enter a number: 4567
Expected Output:
First digit = 4
Last digit = 7
Q63. Write a Java program to find the GCD of two numbers.
Input:
Enter two numbers: 36 60
Expected Output:
GCD = 12
Q64. Write a Java program to find the LCM of two numbers.
Input:
Enter two numbers: 5 7
Expected Output:
LCM = 35
Q65. Write a Java program to print the Fibonacci series up to n terms.
Input:
Enter number of terms: 5
Expected Output:
Fibonacci series: 0 1 1 2 3
Q66. Write a Java program to remove all spaces from a string.
Input:
Enter a string: Hello World
Expected Output:
String without spaces: HelloWorld
Q67. Write a Java program to print all even numbers in a given range.
Input:
Enter start: 1
Enter end: 10
Expected Output:
Even numbers: 2 4 6 8 10
Q68. Write a Java program to print all odd numbers in a given range.
Input:
Enter start: 1
Enter end: 10
Expected Output:
Odd numbers: 1 3 5 7 9
Q69. Write a Java program to count the frequency of each character in a string.
Input:
Enter a string: java
Expected Output:
a: 2
j: 1
v: 1
Q70. Write a Java program to reverse the digits of a number.
Input:
Enter a number: 1234
Expected Output:
Reversed number: 4321
Q71. Write a Java program to find the maximum and minimum elements in an array.
Input:
Enter array elements: 2 8 5 3 9
Expected Output:
Maximum: 9
Minimum: 2
Q72. Write a Java program to convert a decimal number to binary.
Input:
Enter a decimal number: 10
Expected Output:
Binary: 1010
Q73. Write a Java program to convert a binary number to decimal.
Input:
Enter a binary number: 1010
Expected Output:
Decimal: 10
Q74. Write a Java program to calculate the power of a number.
Input:
Enter base: 2
Enter exponent: 3
Expected Output:
Result: 8
Q75. Write a Java program to find the sum of elements in an array.
Input:
Enter array elements: 1 2 3 4
Expected Output:
Sum = 10
Q76. Write a Java program to find the average of numbers in an array.
Input:
Enter array elements: 5 10 15
Expected Output:
Average = 10.0
Q77. Write a Java program to swap two variables without using a third variable.
Input:
Enter x: 5
Enter y: 10
Expected Output:
After swapping: x = 10, y = 5
Q78. Write a Java program to check whether a character is an alphabet or not.
Input:
Enter a character: A
Expected Output:
The character is an alphabet.
Q79. Write a Java program to generate a multiplication table for a number.
Input:
Enter a number: 5
Expected Output:
5 x 1 = 5
5 x 2 = 10
...
5 x 10 = 50
Q80. Write a Java program to check if an array is sorted.
Input:
Enter array elements: 1 2 3 4 5
Expected Output:
The array is sorted.
Q81. Write a Java program to find the second largest element in an array.
Input:
Enter array elements: 10 20 30
Expected Output:
Second largest = 20
Q82. Write a Java program to count the number of digits in a number.
Input:
Enter a number: 12345
Expected Output:
Number of digits = 5
Q83. Write a Java program to replace all vowels in a string with '*'.
Input:
Enter a string: Hello
Expected Output:
H*ll*
Q84. Write a Java program to find the sum of the digits of a number.
Input:
Enter a number: 123
Expected Output:
Sum of digits = 6
Q85. Write a Java program to count the number of words in a string.
Input:
Enter a string: Welcome to Java
Expected Output:
Number of words = 3
Q86. Write a Java program to check if a number is divisible by both 3 and 5.
Input:
Enter a number: 15
Expected Output:
15 is divisible by both 3 and 5.
Q87. Write a Java program to calculate the compound interest.
Input:
Enter principal: 1000
Enter rate: 5
Enter time: 2
Expected Output:
Compound Interest = 1102.5
Q88. Write a Java program to calculate the area of a circle.
Input:
Enter radius: 7
Expected Output:
Area = 153.93804
Q89. Write a Java program to check if a string contains only digits.
Input:
Enter a string: 12345
Expected Output:
The string contains only digits.
Q90. Write a Java program to reverse a string using recursion.
Input:
Enter a string: Java
Expected Output:
Reversed string: avaJ
Q91. Write a Java program to find the factorial of a number using recursion.
Input:
Enter a number: 5
Expected Output:
Factorial = 120
Q92. Write a Java program to print all prime numbers in a given range.
Input:
Enter start: 10
Enter end: 20
Expected Output:
Prime numbers: 11 13 17 19
Q93. Write a Java program to find the length of the longest word in a string.
Input:
Enter a string: Java is amazing
Expected Output:
Longest word length = 7
Q94. Write a Java program to print a right-angled triangle of stars.
Input:
Enter the number of rows: 4
Expected Output:
*
**
***
****
Q95. Write a Java program to remove duplicate elements from an array.
Input:
Enter array elements: 1 2 2 3 4 4
Expected Output:
Array after removing duplicates: 1 2 3 4
Q96. Write a Java program to check if a number is a palindrome.
Input:
Enter a number: 121
Expected Output:
121 is a palindrome.
Q97. Write a Java program to check if a string is a palindrome.
Input:
Enter a string: madam
Expected Output:
madam is a palindrome.
Q98. Write a Java program to calculate the sum of the diagonal elements of a matrix.
Input:
Enter matrix (3x3):
1 2 3
4 5 6
7 8 9
Expected Output:
Sum of diagonal elements = 15
Q99. Write a Java program to find the HCF and LCM of two numbers.
Input:
Enter two numbers: 12 18
Expected Output:
HCF = 6
LCM = 36
Q100. Write a Java program to rotate an array by one position to the right.
Input:
Enter array elements: 1 2 3 4 5
Expected Output:
Rotated array: 5 1 2 3 4