Check palindrome using recursion

1. public class PalindromeUsingRecursionAlgorithm {
2. public static void main(String[] args) {
3. String s = "ABCBAd";
4. boolean flag = isPalindrome(s);
5. if (flag) {
6. System.out.println("Palindrome !!");
7. } else {
8. System.out.println("Not a palindrome !! ");
9. }
10. }
11. 
    
12. public static boolean isPalindrome(String s) {
13. int length = s.length();
14. // An empty string is considered as palindrome
15. if (length == 0) {
16. return true;
17. }
18. int startIndex = 0;
19. int endIndex = length - 1;
20. return palindromeRecursion(s, startIndex, endIndex);
21. }
22. 
    
23. public static boolean palindromeRecursion(String str, int s, int e) {
24. // if there is only character
25. if (s == e) {
26. return true;
27. }
28. // if first and last character do not match
29. if (str.charAt(s) != str.charAt(e)) {
30. return false;
31. }
32. 
    
33. // If there are more than two characters, check if middle substring is
34. // also palindrome or not.
35. 
    
36. if (s < e + 1) {
37. return palindromeRecursion(str, s + 1, e - 1);
38. }
39. return true;
40. }
41. }

Output: Not a palindrome !!