/**
  * if sensor is set to ON the SensorLogger starts logging data for this sensor.
  *
  * @param flag {@code true} to turn sensor ON
  */
 public void setOn(boolean flag) {
   this.sensorIsOn = flag;
   sensorOnOff.clear();
   setRealFreqVisible(flag);
   if (flag) {
     sensorOnOff.add(sensorON);
     for (GeoListBox listbox : listBoxes) {
       if (listbox.getSelection() != null) {
         ((AppWFull) app)
             .getDataCollection()
             .registerGeo(listbox.getType().toString(), listbox.getSelection());
       }
     }
   } else {
     sensorOnOff.add(sensorOFF);
     for (GeoListBox listbox : listBoxes) {
       ((AppWFull) app).getDataCollection().removeRegisteredGeo(listbox.getType());
     }
   }
 }
 /**
  * updates the entries of the given {@link GeoListBox}
  *
  * @param box
  * @param availableObjects
  * @param usedObjects {@link ArrayList}
  */
 private void updateBox(
     GeoListBox box, ArrayList<GeoElement> availableObjects, ArrayList<GeoElement> usedObjects) {
   GeoElement selectedElem = box.getSelection();
   box.clear();
   if (selectedElem != null && usedObjects.contains(selectedElem)) {
     box.addItem(selectedElem);
     box.setSelection(selectedElem);
     box.setSelectedIndex(box.getFirstFreeGeoListBoxIndex());
   } else {
     box.setSelection(null);
   }
   for (GeoElement elem : availableObjects) {
     box.addItem(elem);
   }
 }