code: private static int parsePositiveInteger(final String value) throws NumberFormatException {
  		int number = Integer.parseInt(value);
  		if (number >= 0) {
  			return number;
  		} else {
  			throw new NumberFormatException();
  		}
  	}
docs: Parses a positive integer. In opposite to {@link Integer#parseInt(String)}, this method throws a
  {@link NumberFormatException} for negative values.
  
  @param value
  Number as text
  @return Parsed integer
  @throws NumberFormatException
  Text doesn't contain a valid positive integer