code: private String processIntegerToken(String token) {
          String result = token.replaceAll(""+groupSeparator, "");
          boolean isNegative = false;
          int preLen = negativePrefix.length();
          if ((preLen > 0) && result.startsWith(negativePrefix)) {
              isNegative = true;
              result = result.substring(preLen);
          }
          int sufLen = negativeSuffix.length();
          if ((sufLen > 0) && result.endsWith(negativeSuffix)) {
              isNegative = true;
              result = result.substring(result.length() - sufLen,
                                        result.length());
          }
          if (isNegative)
              result = "-" + result;
          return result;
      }
docs: The integer token must be stripped of prefixes, group separators,
  and suffixes, non ascii digits must be converted into ascii digits
  before parse will accept it.