code: public static boolean isLetterOrDigit(int ch)
      {
          return ((1 << getType(ch))
                  & ((1 << UCharacterCategory.UPPERCASE_LETTER)
                          | (1 << UCharacterCategory.LOWERCASE_LETTER)
                          | (1 << UCharacterCategory.TITLECASE_LETTER)
                          | (1 << UCharacterCategory.MODIFIER_LETTER)
                          | (1 << UCharacterCategory.OTHER_LETTER)
                          | (1 << UCharacterCategory.DECIMAL_DIGIT_NUMBER))) != 0;
      }
docs: Determines if the specified code point is a letter or digit.
  <strong>[icu] Note:</strong> This method, unlike java.lang.Character does not regard the ascii
  characters 'A' - 'Z' and 'a' - 'z' as digits.
  @param ch code point to determine if it is a letter or a digit
  @return true if code point is a letter or a digit