LeetCode Valid Palindrome Solution

Solution.java

class Solution {
    public static boolean isPalindrome(String s) {
        int i = 0;
        int j = s.length()-1;
        boolean result = true;
        if (s.length() == 0 || s.length() == 1)
            return true;
        while(i != j-1) {
            char tempA = s.charAt(i);
            char tempB = s.charAt(j);
            if (isAlfaNumeric(tempA)) {
                if (isAlfaNumeric(tempB)) {
                    if (toLowerCase(tempA) != toLowerCase(tempB)) {
                        result = false;
                        break;
                    } else {
                        j--;
                        i++;
                    }
                } else {
                    j--;
                }
            } else {
                i++;
            }
        }
        return result;
    }

    private static boolean isAlfaNumeric(char c) {
        return (c >= 'a' && c <= 'z') ||
                (c >= 'A' && c <= 'Z') ||
                (c >= '0' && c <= '9');
    }

    private static char toLowerCase(char c) {
        return (c >= 'a' && c <= 'z') ? c : (char)(c - 'A' + 'a');
    }
}