Возврат к primaryStage с другого контроллера

У меня есть Mainpage.fxml, и я открываю Objectpage.fxml на том же этапе. Теперь мне нужно вернуться к Mainpage.fxml через Labelpress, но у меня не получается.

Я уже пытался просто вызвать метод в своем BusinessLogic, но он должен быть статическим. Я не могу допустить, чтобы он был статичным, потому что другие части кода не будут работать.

BusinessLogic.java

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package softwareprojekt;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.ArrayList;

import org.json.JSONException;

import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.layout.AnchorPane;
import javafx.scene.layout.BorderPane;
import javafx.stage.Modality;
import javafx.stage.Stage;
import softwareprojekt.model.Event;
import softwareprojekt.model.MqttEvent;
import softwareprojekt.model.MqttObject;
import softwareprojekt.model.Subject;
import softwareprojekt.util.Parser;
import softwareprojekt.view.EventpageController;
import softwareprojekt.view.MainpageController;
import softwareprojekt.view.NewObjectDialogController;
import softwareprojekt.view.ObjectpageController;

public class BusinessLogic extends Application {

    private Stage primaryStage;
    private BorderPane rootLayout;
    private static final ObservableList<Event> eventData = FXCollections.observableArrayList();
    private static final ObservableList<Subject> subjectData = FXCollections.observableArrayList();
    private static ArrayList<MqttObject> objects = new ArrayList<MqttObject>();
    private static ArrayList<MqttEvent> events = new ArrayList<MqttEvent>();

    public BusinessLogic() {
        eventData.add(new Event("Olaf", "Olafs Zeitpunkt"));
        subjectData.add(new Subject("Peter", "Peters key", "Peters devID", "Peters appID"));
    }

    public static ObservableList<Event> getEventData() {
        return eventData;
    }

    public static ObservableList<Subject> getSubjectData() {
        return subjectData;
    }

    @Override
    public void start(Stage primaryStage) throws Exception {
        this.primaryStage = primaryStage;
        this.primaryStage.setTitle("OneTimeNotifier");

        initRootLayout();

        showMainpage();
    }

    public void init() throws FileNotFoundException, IOException, Exception {
        objects = KeyLoader.loadObjects("keyholder.txt");
        for (MqttObject obj : objects) {
            ClientMQTT mqttObj = new ClientMQTT();
            obj.setMqttObj(mqttObj);
            mqttObj.setAPP_ID(obj.getAppId());
            mqttObj.setKey(obj.getKey());
            mqttObj.start();
        }
    }

    public void initRootLayout() {
        try {
            FXMLLoader loader = new FXMLLoader();
            // Load root layout from fxml file.
            loader.setLocation(BusinessLogic.class.getResource("view/RootLayout.fxml"));
            rootLayout = (BorderPane) loader.load();

            // Show the scene containing the root layout.
            Scene scene = new Scene(rootLayout);
            primaryStage.setScene(scene);

            // Give the controller access to the main app.
            // RootLayoutController controller = loader.getController();
            // controller.setBusinessLogic(this);

            primaryStage.show();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void showMainpage() {
        try {
            FXMLLoader loader = new FXMLLoader();
            // Load maintenance overview.
            loader.setLocation(BusinessLogic.class.getResource("view/Mainpage.fxml"));
            AnchorPane mainpage = (AnchorPane) loader.load();

            // Set maintenance overview into the center of root layout.
            rootLayout.setCenter(mainpage);

            // Give the controller access to the main app.
            MainpageController controller = loader.getController();
            controller.setBusinessLogic(this);

        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public void showEventpage() {
        try {
            FXMLLoader loader = new FXMLLoader();
            loader.setLocation(BusinessLogic.class.getResource("view/Eventpage.fxml"));
            AnchorPane page = (AnchorPane) loader.load();
            primaryStage.setTitle("Eventpage");
            Scene scene = new Scene(page);
            primaryStage.setScene(scene);

            // Give the controller access to the main app.
            EventpageController controller = loader.getController();
            controller.setBusinessLogic(this);

            primaryStage.show();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    public void backToMainpage() {
        try {
            FXMLLoader loader = new FXMLLoader();
            loader.setLocation(BusinessLogic.class.getResource("view/Mainpage.fxml"));
            AnchorPane page = (AnchorPane) loader.load();
            primaryStage.setTitle("Mainpage");
            Scene scene = new Scene(page);
            primaryStage.setScene(scene);

            // Give the controller access to the main app.
            ObjectpageController controller = loader.getController();
            controller.setBusinessLogic(this);

            primaryStage.show();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void showObjectpage() throws IOException {

        try {
            FXMLLoader loader = new FXMLLoader();
            loader.setLocation(BusinessLogic.class.getResource("view/Objectpage.fxml"));
            AnchorPane page = (AnchorPane) loader.load();
            primaryStage.setTitle("Objectpage");
            Scene scene = new Scene(page);
            primaryStage.setScene(scene);

            // Give the controller access to the main app.
            ObjectpageController controller = loader.getController();
            controller.setBusinessLogic(this);

            primaryStage.show();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public boolean showSubjectEditDialog(Subject subject) {
        try {
            FXMLLoader loader = new FXMLLoader();
            loader.setLocation(BusinessLogic.class.getResource("view/NewObjectDialog.fxml"));
            AnchorPane page = (AnchorPane) loader.load();

            Stage dialogStage = new Stage();
            dialogStage.setTitle("Edit subject");
            dialogStage.initModality(Modality.WINDOW_MODAL);
            dialogStage.initOwner(primaryStage);
            Scene scene = new Scene(page);
            dialogStage.setScene(scene);

            NewObjectDialogController controller = loader.getController();
            controller.setDialogStage(dialogStage);
            controller.setSubject(subject);

            dialogStage.showAndWait();

            return controller.isOkClicked();
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }

    public Stage getPrimaryStage() {
        return primaryStage;
    }

    public static void messageArrived(String jsonResponse) throws JSONException {
        MqttEvent newEvent = Parser.parseJSON(jsonResponse, null, "status");
        if (newEvent != null) {
            events.add(newEvent);
            // updateGUI();
        }
    }

    public static void main(String[] args) {
        launch(args);
    }

    public static ObservableList<MqttEvent> getEventsGUI() {
        ObservableList<MqttEvent> currList = FXCollections.observableArrayList(events);
        return currList;
    }

    public static ObservableList<MqttObject> getObjectsGUI() {
        ObservableList<MqttObject> currList = FXCollections.observableArrayList(objects);
        return currList;
    }
}

Контроллер страницы объекта:

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
package softwareprojekt.view;

import javafx.fxml.FXML;
import javafx.scene.control.Alert;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TableColumn;
import javafx.scene.control.TableView;
import javafx.stage.Stage;
import softwareprojekt.BusinessLogic;
import softwareprojekt.model.Subject;

/**
 *
 * @author Schurke
 */
public class ObjectpageController {
    
    
    
    @FXML
    private Label labelTitle;
    @FXML
    private Label labelText1;
    @FXML
    private Label labelText2;
    @FXML
    private Label labelText3;
    @FXML
    private Label labelText4;
    @FXML
    private Label labelBack;
    @FXML
    private Button buttonSub;
    @FXML
    private Button buttonUnsub;
    @FXML
    private Button buttonRefresh;
    @FXML
    private TableView<Subject> subjectTable;
    @FXML
    private TableColumn<Subject, String> column1;
    @FXML
    private TableColumn<Subject, String> column2;
    
    private BusinessLogic businessLogic;
    
    @FXML
    private void initialize(){
        // Initialize the object table with the two columns.
        column1.setCellValueFactory(cellData -> cellData.getValue().nameProperty());
        column2.setCellValueFactory(cellData -> cellData.getValue().keyProperty());
        
        // Listen for selection changes and show the object details when changed.
        subjectTable.getSelectionModel().selectedItemProperty().addListener(
                (observable, oldValue, newValue) -> showSubjectDetails(newValue));
    }
    
    public void setBusinessLogic(BusinessLogic businessLogic){
        this.businessLogic = businessLogic;
        
        subjectTable.setItems(BusinessLogic.getSubjectData());
    }
    
    @FXML
    private void handleButtonSub(){
        Subject tempSubject = new Subject();
        boolean okClicked = businessLogic.showSubjectEditDialog(tempSubject);
        if (okClicked){
            BusinessLogic.getSubjectData().add(tempSubject);
        }
    
    }
    @FXML
    private void handleButtonEdit(){
        Subject selectedSubject = subjectTable.getSelectionModel().getSelectedItem();
        if (selectedSubject != null){
            boolean okClicked = businessLogic.showSubjectEditDialog(selectedSubject);
            if (okClicked){
                showSubjectDetails(selectedSubject);
            }
        } else {
            Alert alert = new Alert(Alert.AlertType.WARNING);
            alert.initOwner(businessLogic.getPrimaryStage());
            alert.setTitle("No Selection");
            alert.setHeaderText("No Subject selected");
            alert.setContentText("Please select a subject.");
            
            alert.showAndWait();
        }
    }
    
    @FXML
    private void handleButtonUnsub() {
        int selectedIndex = subjectTable.getSelectionModel().getSelectedIndex();
        if (selectedIndex >= 0){
            subjectTable.getItems().remove(selectedIndex);
        } else {
            Alert alert = new Alert(Alert.AlertType.WARNING);
            alert.initOwner(businessLogic.getPrimaryStage());
            alert.setTitle("No Selection");
            alert.setHeaderText("No Subject selected");
            alert.setContentText("Please select a subject.");
            
            alert.showAndWait();
        }
    }
    @FXML
    private void handleButtonRefresh() {
        
    }
    @FXML
    private void backActionHandler(){
        Stage stage = (Stage) labelBack.getScene().getWindow();
        stage.close();

        
    }

    private void showSubjectDetails(Subject subject) {
        if (subject != null) {
            labelText1.setText(subject.getName());
            labelText2.setText(subject.getKey());
            labelText3.setText(subject.getDevID());
            labelText4.setText(subject.getAppID());
        } else {
            labelText1.setText("");
            labelText2.setText("");
            labelText3.setText("");
            labelText4.setText("");
        }
    }
}

Я только что вернулся к закрытию окна. Но backActionHandler должен открыть Mainpage.fxml