Add item to listView from external fxml button event

Question

1. I neeed add to listView a new item from external fxml button event. If I click external fxml button I have to insert a new item in a TitledPane that contains a listView but button don't work or I have nullPointExeption

2. TableModel

   java public class MarketItemListView_Model { private String stringa1; private String stringa2; private String stringa3; private String stringa4; private String stringa5; private String stringa6; private String stringa7;

   public MarketItemListView_Model(String stringa1, String stringa2, String stringa3, String stringa4, String stringa5, String stringa6, String stringa7) {
       this.stringa1 = stringa1;
       this.stringa2 = stringa2;
       this.stringa3 = stringa3;
       this.stringa4 = stringa4;
       this.stringa5 = stringa5;
       this.stringa6 = stringa6;
       this.stringa7 = stringa7;
   }
   
   public String getStringa1() {
       return stringa1;
   }
   
   public void setStringa1(String stringa1) {
       this.stringa1 = stringa1;
   }
   
   public String getStringa2() {
       return stringa2;
   }
   
   public void setStringa2(String stringa2) {
       this.stringa2 = stringa2;
   }
   
   public String getStringa3() {
       return stringa3;
   }
   
   public void setStringa3(String stringa3) {
       this.stringa3 = stringa3;
   }
   
   public String getStringa4() {
       return stringa4;
   }
   
   public void setStringa4(String stringa4) {
       this.stringa4 = stringa4;
   }
   
   public String getStringa5() {
       return stringa5;
   }
   
   public void setStringa5(String stringa5) {
       this.stringa5 = stringa5;
   }
   
   public String getStringa6() {
       return stringa6;
   }
   
   public void setStringa6(String stringa6) {
       this.stringa6 = stringa6;
   }
   
   public String getStringa7() {
       return stringa7;
   }
   
   public void setStringa7(String stringa7) {
       this.stringa7 = stringa7;
   }
   

   }

3. controller

   public class Controller implements Initializable { public AnchorPane topPane; public AnchorPane leftPane; public AnchorPane rightPane; public AnchorPane centerPane; public AnchorPane titledPaneAnchorPane;

   @FXML private Label label;
   @FXML
   private ListView listView;
   public TitledPane titledPane;
   
   public ListView getListViewTtiledPane() {
       return listViewTtiledPane;
   }
   
   public ListView<SelectionPane_Model> listViewTtiledPane;
   
   private HBox box;
   
   ObservableList<MarketItemListView_Model> list = FXCollections.observableArrayList();
   @Override
   public void initialize(URL location, ResourceBundle resources) {
       label.setText("text");
       list.add(new MarketItemListView_Model("1","2", "3", "Selection", "5", "6", "7"));
       list.add(new MarketItemListView_Model("1","2", "3", "Selection", "5", "6", "7"));
       list.add(new MarketItemListView_Model("1","2", "3", "Selection", "5", "6", "7"));
       listView.getItems().addAll(list);
       try {
           getBox();
       } catch (IOException e) {
           e.printStackTrace();
       }
   }
   public void getBox() throws IOException {
       listView.setCellFactory(lv -> new ListCell<MarketItemListView_Model>(){
           private Node graphic;
   
           private FXML2Controller controller;
           {
               try {
                   FXMLLoader loader = new FXMLLoader(getClass().getResource("FXML2.fxml"));
                   //FXMLLoader loader = new FXMLLoader(getClass().getResource("marketItemListView.fxml"));
                   graphic = loader.load();
                   controller = loader.getController();
               } catch (IOException e) {
                   e.printStackTrace();
               }
           }
           @Override
           protected  void updateItem(MarketItemListView_Model model, boolean empty){
               super.updateItem(model,empty);
               if(empty){
                   setGraphic(null);
               }else{
                   controller.getItemRootPane().autosize();
                   controller.setBack1(model.getStringa1());
                   controller.setBack2(model.getStringa2());
                   controller.setBack3(model.getStringa3());
                   controller.setSelection(model.getStringa4());
                   controller.setLay1(model.getStringa5());
                   controller.setLay2(model.getStringa6());
                   controller.setLay3(model.getStringa7());
                   setGraphic(graphic);
               }
           }
       });
   }
   

   }

4. FXML2Controller

   public class FXML2Controller implements Initializable {

   public HBox itemRootPane;
   public Label selection;
   public Button back1;
   public Button back2;
   public Button back3;
   public Button lay1;
   public Button lay2;
   public Button lay3;
   
   public HBox getItemRootPane() {
       return itemRootPane;
   }
   
   public void setItemRootPane(HBox itemRootPane) {
       this.itemRootPane = itemRootPane;
   }
   
   public Label getSelection() {
       return selection;
   }
   
   public void setSelection(String text) {
       this.selection.setText(text);
   }
   
   public Button getBack1() {
       return back1;
   }
   
   public void setBack1(String text) {
       back1.setText(text);
   }
   
   public Button getBack2() {
       return back2;
   }
   
   public void setBack2(String text) {
       back2.setText(text);
   }
   
   public Button getBack3() {
       return back3;
   }
   
   public void setBack3(String text) {
       back3.setText(text);
   }
   
   public Button getLay1() {
       return lay1;
   }
   
   public void setLay1(String text) {
       lay1.setText(text);
   }
   
   public Button getLay2() {
       return lay2;
   }
   
   public void setLay2(String text) {
       this.lay2.setText(text);
   }
   
   public Button getLay3() {
       return lay3;
   }
   
   public void setLay3(String text) {
       this.lay3.setText(text);
   }
   
   
   public void showBackPane(ActionEvent actionEvent) throws IOException {
   
       FXMLLoader loader = new FXMLLoader();
       loader.setLocation(getClass().getResource("../home/home.fxml"));
       try {
           loader.load();
       }catch (Exception e){
           System.out.println("e.getMessage() = " + e.getMessage());
       }
       Controller controller = loader.getController();
   
       //??????????????
       /*
   
       I NEED TO IMPLEMENT BUTTON ACTION EVENT
        */
   }
   
   @Override
   public void initialize(URL location, ResourceBundle resources) {
   
   }
   

   }