public ActionForward listClasses(ActionMapping mapping, ActionForm form, HttpServletRequest request,
HttpServletResponse response) throws Exception {
AcademicInterval academicInterval =
AcademicInterval.getAcademicIntervalFromResumedString((String) request
.getAttribute(PresentationConstants.ACADEMIC_INTERVAL));
InfoCurricularYear infoCurricularYear = (InfoCurricularYear) request.getAttribute(PresentationConstants.CURRICULAR_YEAR);
InfoExecutionDegree infoExecutionDegree =
(InfoExecutionDegree) request.getAttribute(PresentationConstants.EXECUTION_DEGREE);
final ExecutionDegree executionDegree = FenixFramework.getDomainObject(infoExecutionDegree.getExternalId());
final Set<SchoolClass> classes;
Integer curricularYear = infoCurricularYear.getYear();
if (curricularYear != null) {
classes = executionDegree.findSchoolClassesByAcademicIntervalAndCurricularYear(academicInterval, curricularYear);
} else {
classes = executionDegree.findSchoolClassesByAcademicInterval(academicInterval);
}