Another way, if the form uses "POST", would be to use the request's input stream to read the posted data directly from the request's body content, and then parse it into parameter names and values yourself.
You'd need to avoid making any calls to "getParameter" beforehand, as the first such call causes the input stream to be consumed (it retrieves and parses the posted data, and merges it with any request parameters found in the query
string - which leaves the input stream already-consumed and at end-of-file).
I can't think off-hand of many situations where this would be worthwhile, but if the request has both posted data and a normal query string this approach does let you access the two sets of parameters entirely separately from each other (even if they both have parameters with the same name) - i.e. retrieve the posted data from the input stream, then use getParameter to retrieve the query string parameters on their own. You could also use this regardless of the request's content type, whereas getParameter only reads posted data if its content type is specifically that expected for posted form data.
At any rate, reading the posted data directly from the input stream is another way to do it, and maybe (just maybe) that's what the interviewer was after.