Palindrome.java

package String;

public class Palindrome {

    public static boolean isPalindrome(String s) {
        if (s.isEmpty()) return true;

        int start = 0;
        int last = s.length() - 1;

        while (start <= last) {
            char currFirst = s.charAt(start);
            char currLast = s.charAt(last);

            if (!Character.isLetterOrDigit(currFirst)) start++;
            else if (!Character.isLetterOrDigit(currLast)) last--;
            else {
                if (Character.toLowerCase(currFirst) != Character.toLowerCase(currLast)) return false;
                start++;
                last--;
            }
        }
        return true;
    }

    public static void main(String[] args) {
        String s = "A man, a plan, a canal: Panama";
        System.out.println(isPalindrome(s));
    }
}