回文数串

public boolean isPalindrome(String s) {
s = s.replaceAll("[^a-zA-Z0-9]", "").toLowerCase();

    char[] chars = s.toCharArray();

    int i = 0;
    int j = chars.length - 1;

    while (i < j) {
        if (chars[i] == chars[j]) {
            i++;
            j--;
        } else {
            return false;
        }
    }
    
    return true;
}