code: static boolean isLatin(String s) {
      int len = s.length();
      for (int index = 0; index < len; index++) {
        char c = s.charAt(index);
        if (c > LARGEST_BASIC_LATIN) {
          return false;
        }
      }
      return true;
    }
docs: Test if all characters in the string are in the Basic Latin (aka ASCII) character set - that
  they have UTF-16 values equal to or below 0x7f. This check can find which identifiers with
  Unicode characters need to be escaped in order to allow resulting files to be processed by
  non-Unicode aware UNIX tools and editors. * See
  http://en.wikipedia.org/wiki/Latin_characters_in_Unicode for more on Basic Latin.
  
  @param s The string to be checked for ASCII-goodness.
  @return True if all characters in the string are in Basic Latin set.