code: protected int extractDigit(final char value) throws NumberFormatException {
      if (Character.isDigit(value)) {
        return Character.digit(value, DEC_RADIX);
      } else {
        throw LOG.getCharacterIsNotADigitException(value);
      }
    }
docs: Returns the numeric {@code int} value of a {@code char}.
  
  @param value the input {@code char} to be parsed
  
  @return the numeric {@code int} value represented by the character.
  
  @throws NumberFormatException in case character is not a digit