One Servlet servers few multipart forms - forms

Question

i will have few multipart forms in jsp and have to process them using servlet. All work fine with the first form, but if i try to add switch in servlet's doPost method, it stops to recognize fields value: userName cannot be null.
jsp form:
<form action="ServletMultipartForm" method="post" name="Form" enctype="multipart/form-data">
<br>
<label>NAME</label><br>
<input type="text" name="instrName">
<label>IMAGE</label><br>
<input type="file" name="instrImage">
<input type="submit" value="Submit Instructor" name="action">
</form>
ServletMultipartForm.java
#MultipartConfig
public class ServletMultipartForm extends HttpServlet {
private final String UPLOAD_DIRECTORY = "F:/OLD/JAVAJSP - Copy/PROGRAMMING_ASSIGNMENT3/ASpace/web/img/instructors";
String userImage = null;
String userName = null;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
List<FileItem> items = null;
try {
items = new ServletFileUpload(new DiskFileItemFactory()).parseRequest(request);
} catch (FileUploadException ex) {
Logger.getLogger(ServletMultipartForm.class.getName()).log(Level.SEVERE, null, ex);
}
for (FileItem item : items) {
if (item.isFormField()) {
// Process regular form field (input type="text|radio|checkbox|etc", select, etc).
String fieldname = item.getFieldName();
String fieldvalue = item.getString();
if (fieldname.equalsIgnoreCase("instrName")) {
userName = fieldvalue;
}
} else {
FileItemFactory factory = new DiskFileItemFactory();
ServletFileUpload upload = new ServletFileUpload(factory);
try {
// Parse the request
List<FileItem> multiparts = upload.parseRequest(request);
userImage = new File(item.getName()).getName();
item.write(new File(UPLOAD_DIRECTORY + File.separator + userImage));
System.out.println("User Image Name " + userImage);
} catch (FileUploadException e) {
throw new ServletException("Cannot parse multipart request.", e);
} catch (Exception ex) {
Logger.getLogger(ServletMultipartForm.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
User in=new User(userName, userImage);
UserDB.insert(in);
String FeedbackMessage = "New Instructor " + in.getUserName()+" was added";
request.setAttribute("FeedbackMessage", FeedbackMessage);
getServletContext()
.getRequestDispatcher("/adminPanel.jsp")
.forward(request, response);
gotoPage("/adminPanel.jsp", request, response);
}
private void gotoPage(String address, HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
RequestDispatcher dispatcher = getServletContext().getRequestDispatcher(address);
dispatcher.forward(request, response);
}
}
I have tried to add switch statement depending on "action", smth:
String selection = request.getParameter("action");
but then start to get that error: userName cannot be null.
Thanks for any advice.