Palindrome.java

package com.thealgorithms.strings;

/**
 * Wikipedia: https://en.wikipedia.org/wiki/Palindrome
 */
final class Palindrome {
    private Palindrome() {
    }

    /**
     * Check if a string is palindrome string or not using String Builder
     *
     * @param s a string to check
     * @return {@code true} if given string is palindrome, otherwise
     * {@code false}
     */
    public static boolean isPalindrome(String s) {
        return ((s == null || s.length() <= 1) || s.equals(new StringBuilder(s).reverse().toString()));
    }

    /**
     * Check if a string is palindrome string or not using recursion
     *
     * @param s a string to check
     * @return {@code true} if given string is palindrome, otherwise
     * {@code false}
     */
    public static boolean isPalindromeRecursion(String s) {
        if (s == null || s.length() <= 1) {
            return true;
        }

        if (s.charAt(0) != s.charAt(s.length() - 1)) {
            return false;
        }

        return isPalindromeRecursion(s.substring(1, s.length() - 1));
    }

    /**
     * Check if a string is palindrome string or not using two pointer technique
     *
     * @param s a string to check
     * @return {@code true} if given string is palindrome, otherwise
     * {@code false}
     */
    public static boolean isPalindromeTwoPointer(String s) {
        if (s == null || s.length() <= 1) {
            return true;
        }
        for (int i = 0, j = s.length() - 1; i < j; ++i, --j) {
            if (s.charAt(i) != s.charAt(j)) {
                return false;
            }
        }
        return true;
    }
}

/**
*check if string is palindrome or not
* 
* @param s a string to check
* @return {@code true} if given string is palindrome, otherwise
* {@code false}
*/
public static boolean isPalindromeTwoPointerwhileloop(String s){
    char[] charArray = word.to char Array();
    int start=0; int end= s.length-1;
    while(start<end){
        if (char Array[start]!= char Array[end]){
            return false;
        }
        start++; end--;
    }
    return true;
}