java.lang.reflect.InvocationTargetException in Application start method

Question

I'm working on a gui app, using javafx. I tried running the Main app, but I keep getting an error.

Exception in Application start method
java.lang.reflect.InvocationTargetException
        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:118)
        at java.base/java.lang.reflect.Method.invoke(Method.java:580)
        at [email protected]/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464)
        at [email protected]/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:364)
        at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
        at java.base/java.lang.reflect.Method.invoke(Method.java:580)
        at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1135)
Caused by: java.lang.RuntimeException: Exception in Application start method
        at [email protected]/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:893)
        at [email protected]/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:196)
        at java.base/java.lang.Thread.run(Thread.java:1583)
Caused by: javafx.fxml.LoadException: 
/Users/mac/Documents/YK_Project/MusicalBookingTicketApp/bin/musicalticketbooking/musicals.fxml

        at [email protected]/javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2722)
        at [email protected]/javafx.fxml.FXMLLoader.importClass(FXMLLoader.java:2994)
        at [email protected]/javafx.fxml.FXMLLoader.processImport(FXMLLoader.java:2838)
        at [email protected]/javafx.fxml.FXMLLoader.processProcessingInstruction(FXMLLoader.java:2773)
        at [email protected]/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2639)
        at [email protected]/javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2563)
        at [email protected]/javafx.fxml.FXMLLoader.load(FXMLLoader.java:2531)
        at musicalticketbooking.Main.start(Main.java:14)
        at [email protected]/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:839)
        at [email protected]/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:483)
        at [email protected]/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:456)
        at java.base/java.security.AccessController.doPrivileged(AccessController.java:400)
        at [email protected]/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:455)
        at [email protected]/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
Caused by: java.lang.ClassNotFoundException: javafx.scene.control.HBox
        at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
        at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
        at [email protected]/javafx.fxml.FXMLLoader.loadTypeForPackage(FXMLLoader.java:3062)
        at [email protected]/javafx.fxml.FXMLLoader.loadType(FXMLLoader.java:3051)
        at [email protected]/javafx.fxml.FXMLLoader.importClass(FXMLLoader.java:2992)
        ... 12 more
Exception running application musicalticketbooking.Main

I'm using java 21.0.1 2023-10-17 LTS and javafx-sdk-21.0.1 and using vscode as my IDE

Here's what I have so far:
Main.java:

package musicalticketbooking;

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

public class Main extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("musicals.fxml"));
        Parent root = loader.load();
        Scene scene = new Scene(root);
    
        // Set the controller for the FXML file
        Controller controller = loader.getController();
    
        stage.setTitle("Musical Ticket Booking System");
        stage.setScene(scene);
        stage.show();
    }
    

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

Controller.java

package musicalticketbooking;

import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;

public class Controller {

    @FXML
    private VBox musicalLists;

    @FXML
    private VBox schedules;

    @FXML
    private VBox formTicket;

    @FXML
    private Button bookButton;

    @FXML
    private void handleMusicals() {
        
    }

    @FXML
    private void handleSchedule() {
        
    }

    @FXML
    private void handleExit() {

    }

    @FXML
    private void handleBook() {
        
    }
}

musicals.fxml:

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

<?import javafx.scene.control.Button?>
<?import javafx.scene.control.HBox?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.VBox?>

<VBox xmlns="http://javafx.com/javafx"
    xmlns:fx="http://javafx.com/fxml"
    fx:controller="musicalticketbooking.Controller">

    <Label text="Musical Ticket Booking System"/>

    <HBox spacing="10">
        <Button text="Musical List" onAction="#handleMusicals"/>
        <Button text="Schedule List" onAction="#handleSchedule"/>
        <Button text="Exit" onAction="#handleExit"/>
    </HBox>

    <VBox id="data-container">
        <!-- Musical List -->
        <VBox id="musical-lists">
            <!-- Populate dynamically from Java code -->
        </VBox>

        <!-- Schedule List -->
        <VBox id="schedules">
            <!-- Populate dynamically from Java code -->
        </VBox>

        <VBox id="form-ticket">
            <!-- Populate dynamically from Java code -->
        </VBox>
    </VBox>

    <Button text="Book" onAction="#handleBook"/>

</VBox>

And my lunch.json:

{
  // Use IntelliSense to learn about possible attributes.
  // Hover to view descriptions of existing attributes.
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "type": "java",
      "name": "Musical Ticket Booking App",
      "request": "launch",
      "mainClass": "musicalticketbooking.Main",
      "vmArgs": "--module-path /Users/mac/Downloads/javafx-sdk-21.0.1/lib --add-modules javafx.controls,javafx.fxml"
    }
  ]
}

All files are in the same package musicalticketbooking;

Answer 1

Caused by: java.lang.ClassNotFoundException: javafx.scene.control.HBox

You have to change the import of the fxml file (musicals.fxml) from

<?import javafx.scene.control.HBox ?>

to:

<?import javafx.scene.layout.HBox ?>