I have SortedMap in Servlet to populate drop down values in JSP and I have the following code
SortedMap dept = findDepartment();
I think above examples are correct. but you dont' really need to set
request.setAttribute("selectedDept", selectedDept);
you can reuse that info from JSTL, just do something like this..
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>