JavaFx Login Page not shutting down when called close from a method of another class?

Question

enter image description hereI am opening a Login JavaFX page from UserController.java and it has its control in LoginController.java.After processing it in LoginController.java and I am executing a close method to close the stage declared in UserController(which contains the stage for Login) but it throws NullPointerException

public class UserMenuController {
    @FXML
    private MenuItem Login;
    Stage loginStage;

    public void LoginPage(ActionEvent actionEvent) throws IOException {
        loginStage=new Stage();
        Parent loginFXML=FXMLLoader.load(getClass().getResource("/login.fxml"));
        loginStage.setTitle("Login");
        Scene loginScene=new Scene(loginFXML);
        loginStage.setScene(loginScene);
        loginStage.show();

    }
    public void shutLoginStage(){
        loginStage.close();
    }
}

public class LoginController implements Initializable {
    @FXML
    private WebView view;
    UserMenuController u=new UserMenuController();

    public void initialize(URL location, ResourceBundle resources) {
        view.getEngine().load("https://kite.trade/connect/login?v=3&api_key=kpnnt4xthv187j8p");
        view.getEngine().getLoadWorker().stateProperty().addListener((observable, oldValue, newValue) -> {[enter image description here][1]
            //Gets the URL  Request Token
            if (newValue.equals(Worker.State.FAILED)) {
                //System.out.println(view.getEngine().getLocation());
                System.out.println(view.getEngine().getLocation());
                u.shutLoginStage();

            }

        });

Answer 1

Make Stage loginStage = new Stage(); Global.

MCVE

Controller

import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.stage.Stage;

/**
 *
 * @author blj0011
 */
public class FXMLDocumentController implements Initializable
{

    @FXML
    private Label label;

    Stage loginStage = new Stage();

    ;

    @FXML
    private void handleButtonAction(ActionEvent event)
    {
        try {
            Parent loginFXML = FXMLLoader.load(getClass().getResource("Login.fxml"));
            loginStage.setTitle("Login");
            Scene loginScene = new Scene(loginFXML);
            loginStage.show();
        }
        catch (IOException ex) {
            Logger.getLogger(FXMLDocumentController.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    @FXML
    private void shutLoginStage(ActionEvent event)
    {
        if (loginStage.isShowing()) {//If the loginStage is showing, close it.
            loginStage.close();
        }
    }

    @Override
    public void initialize(URL url, ResourceBundle rb)
    {
        // TODO
    }

}

FXML

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.AnchorPane?>

<AnchorPane id="AnchorPane" prefHeight="200" prefWidth="320" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8.0.141" fx:controller="javafxapplication246.FXMLDocumentController">
    <children>
        <Button fx:id="button" layoutX="126" layoutY="90" onAction="#handleButtonAction" text="Click Me!" />
        <Label fx:id="label" layoutX="126" layoutY="120" minHeight="16" minWidth="69" />
      <Button layoutX="133.0" layoutY="137.0" mnemonicParsing="false" onAction="#shutLoginStage" text="Close" />
    </children>
</AnchorPane>

**Login Controller**

import java.net.URL;
import java.util.ResourceBundle;
import javafx.fxml.Initializable;

/**
 * FXML Controller class
 *
 * @author blj0011
 */
public class LoginController implements Initializable
{

    /**
     * Initializes the controller class.
     * @param url
     * @param rb
     */
    @Override
    public void initialize(URL url, ResourceBundle rb)
    {
        // TODO
    }

}

Login FXML

<?xml version="1.0" encoding="UTF-8"?>

<?import java.lang.*?>
<?import java.util.*?>
<?import javafx.scene.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" xmlns:fx="http://javafx.com/fxml/1" fx:controller="javafxapplication246.LoginController">

</AnchorPane>

Main

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

/**
 *
 * @author blj0011
 */
public class JavaFXApplication246 extends Application
{

    @Override
    public void start(Stage stage) throws Exception
    {
        Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));

        Scene scene = new Scene(root);

        stage.setScene(scene);
        stage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args)
    {
        launch(args);
    }

}