
Practice 70 Java Recursive Methods Programming Questions
Q1. Write a Java program to find the factorial of a number using recursion.
Input:
Enter a number: 5
Expected Output:
Factorial of 5 is 120
Q2. Write a Java program to find the sum of the digits of a number using recursion.
Input:
Enter a number: 123
Expected Output:
Sum of digits: 6
Q3. Write a Java program to find the power of a number using recursion.
Input:
Enter the base number: 2
Enter the exponent: 3
Expected Output:
2 raised to the power of 3 is 8
Q4. Write a Java program to print Fibonacci series up to n terms using recursion.
Input:
Enter number of terms: 6
Expected Output:
Fibonacci series: 0 1 1 2 3 5
Q5. Write a Java program to check if a number is a palindrome using recursion.
Input:
Enter a number: 121
Expected Output:
The number 121 is a palindrome.
Q6. Write a Java program to find the greatest common divisor (GCD) of two numbers using recursion.
Input:
Enter two numbers: 36 60
Expected Output:
GCD of 36 and 60 is 12
Q7. Write a Java program to reverse a string using recursion.
Input:
Enter a string: hello
Expected Output:
Reversed string: olleh
Q8. Write a Java program to find the nth term of the Fibonacci series using recursion.
Input:
Enter the position: 6
Expected Output:
The 6th term of Fibonacci series is 5
Q9. Write a Java program to count the number of digits in a number using recursion.
Input:
Enter a number: 54321
Expected Output:
The number of digits is 5
Q10. Write a Java program to check if a number is prime using recursion.
Input:
Enter a number: 7
Expected Output:
7 is a prime number.
Q11. Write a Java program to find the sum of first n natural numbers using recursion.
Input:
Enter a number: 5
Expected Output:
Sum of first 5 natural numbers is 15
Q12. Write a Java program to find the length of a string using recursion.
Input:
Enter a string: recursion
Expected Output:
The length of the string is 9
Q13. Write a Java program to find the sum of an array using recursion.
Input:
Enter array elements: 1 2 3 4 5
Expected Output:
Sum of the array elements is 15
Q14. Write a Java program to find the product of an array using recursion.
Input:
Enter array elements: 1 2 3 4 5
Expected Output:
Product of the array elements is 120
Q15. Write a Java program to print a number in reverse order using recursion.
Input:
Enter a number: 12345
Expected Output:
Reversed number: 54321
Q16. Write a Java program to find the sum of even numbers up to n using recursion.
Input:
Enter a number: 6
Expected Output:
Sum of even numbers up to 6 is 12
Q17. Write a Java program to find the sum of odd numbers up to n using recursion.
Input:
Enter a number: 6
Expected Output:
Sum of odd numbers up to 6 is 9
Q18. Write a Java program to calculate the factorial of a number using tail recursion.
Input:
Enter a number: 5
Expected Output:
Factorial of 5 is 120
Q19. Write a Java program to find the first n prime numbers using recursion.
Input:
Enter a number: 5
Expected Output:
First 5 prime numbers are: 2 3 5 7 11
Q20. Write a Java program to find the sum of elements in a matrix using recursion.
Input:
Enter matrix elements: 1 2 3 4 5 6
Expected Output:
Sum of the matrix elements is 21
Q21. Write a Java program to find the Fibonacci series up to nth term using recursion.
Input:
Enter the number of terms: 6
Expected Output:
Fibonacci series: 0 1 1 2 3 5
Q22. Write a Java program to print a number in binary using recursion.
Input:
Enter a number: 13
Expected Output:
Binary representation of 13 is 1101
Q23. Write a Java program to find the maximum element in an array using recursion.
Input:
Enter array elements: 2 4 5 7 1
Expected Output:
Maximum element in the array is 7
Q24. Write a Java program to find the minimum element in an array using recursion.
Input:
Enter array elements: 2 4 5 7 1
Expected Output:
Minimum element in the array is 1
Q25. Write a Java program to reverse an array using recursion.
Input:
Enter array elements: 1 2 3 4 5
Expected Output:
Reversed array: 5 4 3 2 1
Q26. Write a Java program to find the sum of numbers from 1 to n using recursion.
Input:
Enter a number: 4
Expected Output:
Sum of numbers from 1 to 4 is 10
Q27. Write a Java program to calculate the nth power of a number using recursion.
Input:
Enter the base number: 2
Enter the exponent: 3
Expected Output:
2 raised to the power of 3 is 8
Q28. Write a Java program to calculate the nth triangular number using recursion.
Input:
Enter a number: 4
Expected Output:
The 4th triangular number is 10
Q29. Write a Java program to check if a string is a palindrome using recursion.
Input:
Enter a string: madam
Expected Output:
The string "madam" is a palindrome.
Q30. Write a Java program to print a number pattern using recursion.
Input:
Enter a number: 3
Expected Output:
1
1 2
1 2 3
Q31. Write a Java program to find the sum of squares of numbers up to n using recursion.
Input:
Enter a number: 3
Expected Output:
Sum of squares up to 3 is 14
Q32. Write a Java program to calculate the length of a linked list using recursion.
Input:
Enter elements of the linked list: 1 2 3
Expected Output:
Length of the linked list is 3
Q33. Write a Java program to find the difference between the largest and smallest elements in an array using recursion.
Input:
Enter array elements: 1 4 7 2 5
Expected Output:
The difference between largest and smallest is 6
Q34. Write a Java program to calculate the sum of all numbers divisible by 3 using recursion.
Input:
Enter a number: 6
Expected Output:
Sum of numbers divisible by 3 up to 6 is 9
Q35. Write a Java program to count the number of vowels in a string using recursion.
Input:
Enter a string: hello
Expected Output:
Number of vowels in the string: 2
Q36. Write a Java program to print numbers in descending order from n using recursion.
Input:
Enter a number: 5
Expected Output:
5 4 3 2 1
Q37. Write a Java program to check if a number is a perfect number using recursion.
Input:
Enter a number: 6
Expected Output:
6 is a perfect number.
Q38. Write a Java program to calculate the nth Fibonacci number using recursion.
Input:
Enter a number: 5
Expected Output:
The 5th Fibonacci number is 5
Q39. Write a Java program to find the sum of the first n odd numbers using recursion.
Input:
Enter a number: 4
Expected Output:
Sum of first 4 odd numbers is 16
Q40. Write a Java program to print a pattern of stars using recursion.
Input:
Enter a number: 3
Expected Output:
*
* *
* * *
Q41. Write a Java program to find the least common multiple (LCM) of two numbers using recursion.
Input:
Enter two numbers: 4 6
Expected Output:
LCM of 4 and 6 is 12
Q42. Write a Java program to find the sum of the first n even numbers using recursion.
Input:
Enter a number: 4
Expected Output:
Sum of first 4 even numbers is 20
Q43. Write a Java program to find the second largest number in an array using recursion.
Input:
Enter array elements: 2 4 1 5 3
Expected Output:
Second largest number in the array is 4
Q44. Write a Java program to find the sum of digits of a number using recursion.
Input:
Enter a number: 54321
Expected Output:
Sum of digits is 15
Q45. Write a Java program to check if a number is an Armstrong number using recursion.
Input:
Enter a number: 153
Expected Output:
153 is an Armstrong number.
Q46. Write a Java program to find the product of digits of a number using recursion.
Input:
Enter a number: 123
Expected Output:
Product of digits is 6
Q47. Write a Java program to print a pyramid pattern using recursion.
Input:
Enter a number: 3
Expected Output:
*
* *
* * *
Q48. Write a Java program to find the greatest element in a set using recursion.
Input:
Enter set elements: 1 4 6 2
Expected Output:
Greatest element is 6
Q49. Write a Java program to calculate the sum of the series 1 + 1/2 + 1/3 + ... + 1/n using recursion.
Input:
Enter a number: 3
Expected Output:
Sum of the series is 1.83333
Q50. Write a Java program to check if a number is divisible by 2 using recursion.
Input:
Enter a number: 4
Expected Output:
The number is divisible by 2.
Q51. Write a Java program to print the factors of a number using recursion.
Input:
Enter a number: 6
Expected Output:
Factors of 6 are: 1 2 3 6
Q52. Write a Java program to check if a string contains only digits using recursion.
Input:
Enter a string: 12345
Expected Output:
The string contains only digits.
Q53. Write a Java program to find the nth triangular number using recursion.
Input:
Enter a number: 4
Expected Output:
The 4th triangular number is 10
Q54. Write a Java program to find the sum of first n odd numbers using recursion.
Input:
Enter a number: 4
Expected Output:
Sum of first 4 odd numbers is 16
Q55. Write a Java program to calculate the factorial of a number using recursion.
Input:
Enter a number: 5
Expected Output:
Factorial of 5 is 120
Q56. Write a Java program to print the first n natural numbers using recursion.
Input:
Enter a number: 3
Expected Output:
1 2 3
Q57. Write a Java program to find the sum of squares of numbers up to n using recursion.
Input:
Enter a number: 3
Expected Output:
Sum of squares up to 3 is 14
Q58. Write a Java program to check if a number is a perfect square using recursion.
Input:
Enter a number: 16
Expected Output:
16 is a perfect square.
Q59. Write a Java program to reverse a string using recursion.
Input:
Enter a string: hello
Expected Output:
Reversed string: olleh
Q60. Write a Java program to print a diamond pattern using recursion.
Input:
Enter a number: 3
Expected Output:
*
* *
* * *
* *
*
Q61. Write a Java program to find the sum of all digits of a number using recursion.
Input:
Enter a number: 123
Expected Output:
Sum of digits is 6
Q62. Write a Java program to check if a string is a palindrome using recursion.
Input:
Enter a string: madam
Expected Output:
The string "madam" is a palindrome.
Q63. Write a Java program to print the factorial of a number using recursion.
Input:
Enter a number: 5
Expected Output:
Factorial of 5 is 120
Q64. Write a Java program to find the sum of elements in an array using recursion.
Input:
Enter array elements: 1 2 3 4
Expected Output:
Sum of the array elements is 10
Q65. Write a Java program to calculate the nth Fibonacci number using recursion.
Input:
Enter a number: 5
Expected Output:
Fibonacci number at position 5 is 5
Q66. Write a Java program to check if a number is even or odd using recursion.
Input:
Enter a number: 4
Expected Output:
The number is even.
Q67. Write a Java program to find the largest element in an array using recursion.
Input:
Enter array elements: 1 2 5 3
Expected Output:
Largest element is 5
Q68. Write a Java program to calculate the sum of cubes of the first n natural numbers using recursion.
Input:
Enter a number: 3
Expected Output:
Sum of cubes up to 3 is 36
Q69. Write a Java program to calculate the sum of all even digits of a number using recursion.
Input:
Enter a number: 123456
Expected Output:
Sum of even digits is 12
Q70. Write a Java program to print a number pattern (reverse) using recursion.
Input:
Enter a number: 5
Expected Output:
5 4 3 2 1