Palindrome

public static boolean isPalindrome(String inputString) {
  StringBuilder sb = new StringBuilder();
  for (Character c: inputString.toCharArray()) {
    if (Character.isLetter(c)) {
      sb.append(c);
    }
  }
  String forward = sb.toString().toLowerCase();
  String backward = sb.reverse().toString().toLowerCase();
  return forward.equals(backward);
}