//code voor de toevoegknop van een nieuwe activiteit in de activiteitenlijst private void Btntoevoegen_Click(object sender, EventArgs e) { Activity_Service activityService = new Activity_Service(); AddCalendar.MaxSelectionCount = 1; string AddedDescription = Txtaddomschrijving.Text; DateTime AddedStartTime = AddCalendar.SelectionRange.Start; int AddedNumberofStudents = int.Parse(Txtaddstudentenaantal.Text); int AddedNumberofLecturers = int.Parse(Txtadddocentenaantal.Text); if (AddedDescription != "" && AddedStartTime != null && AddedNumberofStudents != 0 && AddedNumberofLecturers != 0) { activityService.AddNewActivity(AddedDescription, AddedStartTime, AddedNumberofStudents, AddedNumberofLecturers); } ShowPanel("Activities"); }