Problem with as/400 jdbc driver

While iterating over the resultset obtained from an as/400 datasource today, I was constantly getting this error:

descriptor index not valid

Upon searching for this error, I found its solution that should better be shared with everyone.
The jdbc driver starts the columns from 1 instead of 0 index, so when calling some data from the ResultSet object, such as resultSet.getString(1), the column fetched is the first column, and not the second column as it seems.
It could be nice if the error message explained this problem in a non-cryptic manner. This problem is one of those nagging problems that repeat from time to time(as this api doesn't seem to conform to java conventions in this case).