Valid Palindrome

public class Solution {
    public boolean isPalindrome(String s) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if(s == null || s.length() < 2)
            return true;
        String mystring = s.replaceAll("[^A-Za-z0-9]","");
        mystring = mystring.toLowerCase();
        for(int i = 0; i < (mystring.length() / 2); i++)
            if(mystring.charAt(i) != mystring.charAt(mystring.length() - 1 - i))
                return false;
        return true;
    }
}