public void fillComboBox() {
        for(Person p: hospital.allUsers.values()){
            Patient patient = (Patient)p;
            admitPatient_patientComboBox.addItem(patient.getFirstName());
            emailPatient_patientComboBox.addItem(patient.getFirstName());
        }

        //location/department combobox
        for(Department d: hospital.getAllDepartments())
            admitPatient_locationComboBox.addItem(d.getDepartmentName());

        //Room number combobox
        for(Room room: hospital.getAllRooms()){
            admitPatient_roomNumberComboBox.addItem(room.getRoomNum());
            roomChange_newRoomComboBox.addItem(room.getRoomNum());
        }

        //Doctor combobox admit Patient Page
        for(Person o: hospital.allStaff.values()){
            if(o.getType() == 2) {
                Doctor doctor = (Doctor)o;
                admitPatient_doctorComboBox.addItem("Dr. " + doctor.getLastName());
                newPatient_physicianComboBox.addItem("Dr. " + doctor.getLastName());
                scheduleSurgery_primPhysicianComboBox.addItem("Dr. " + doctor.getLastName());
            } else if(o.getType() == 1) {
                Surgeon surgeon = (Surgeon)o;
                scheduleSurgery_attnPhysicianComboBox.addItem("Dr. " + surgeon.getLastName());
            } else if(o.getType() == 4) {
                Nurse nurse = (Nurse)o;
                scheduleSurgery_nurseComboBox.addItem("Nurse " + nurse.getLastName());
            }
        }
    }