JavaFX / Intellij errors

Question

I'm trying to set up my programing environment in Java.
I Have Ubuntu 18.04LTS / Java SE Runtime Environment (build 13.0.1+9)/ Intellij/ JavaFX Scene Builder 11.0.0
I have followed this tutorial : https://www.youtube.com/watch?v=T3NlWMzPyXM
The following 3 files were created:

Main.java :

package sample;

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 primaryStage) throws Exception{
        Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root, 300, 275));
        primaryStage.show();
    }


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

Controller.java :

package sample;

import javafx.event.ActionEvent;

public class Controller {

//    I start writing the code here:
    public void pressButton(ActionEvent event) {
        System.out.println("You have pressed the button");


    }



}

sample.fxml :

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

<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>

<GridPane alignment="center" hgap="10" prefHeight="300.0" prefWidth="300.0" vgap="10" xmlns="http://javafx.com/javafx/10.0.2-internal" xmlns:fx="http://javafx.com/fxml/1" fx:controller="sample.Controller">
   <columnConstraints>
      <ColumnConstraints />
   </columnConstraints>
   <rowConstraints>
      <RowConstraints />
   </rowConstraints>
   <children>
      <Button fx:id="btn_msg" mnemonicParsing="false" onAction="#pressButton" prefHeight="109.0" prefWidth="121.0" text="Button" />
   </children>
</GridPane>

When I run application I receive the following output errors:

/usr/lib/jvm/java-13-oracle/bin/java --add-modules javafx.base,javafx.graphics --add-reads javafx.base=ALL-UNNAMED --add-reads javafx.graphics=ALL-UNNAMED -Djava.library.path=/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib -javaagent:/snap/intellij-idea-community/185/lib/idea_rt.jar=34245:/snap/intellij-idea-community/185/bin -Dfile.encoding=UTF-8 -classpath "/home/leo/IdeaProjects/Java kurs kenis/FX_trial2/out/production/FX_trial2:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/src.zip:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx-swt.jar:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx.web.jar:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx.base.jar:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx.fxml.jar:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx.media.jar:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx.swing.jar:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx.controls.jar:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx.graphics.jar" -p /home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx.base.jar:/home/leo/IdeaProjects/javafx-sdk-11.0.2/lib/javafx.graphics.jar sample.Main
Exception in Application start method
java.lang.reflect.InvocationTargetException
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:567)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:464)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:363)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:567)
    at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1051)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195)
    at java.base/java.lang.Thread.run(Thread.java:830)
Caused by: java.lang.IllegalAccessError: class com.sun.javafx.fxml.FXMLLoaderHelper (in unnamed module @0xc9d8652) cannot access class com.sun.javafx.util.Utils (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.util to unnamed module @0xc9d8652
    at com.sun.javafx.fxml.FXMLLoaderHelper.<clinit>(FXMLLoaderHelper.java:38)
    at javafx.fxml.FXMLLoader.<clinit>(FXMLLoader.java:2056)
    at sample.Main.start(Main.java:13)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:391)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
    at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
    at javafx.graphics/com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
    at javafx.graphics/com.sun.glass.ui.gtk.GtkApplication.lambda$runLoop$11(GtkApplication.java:277)
    ... 1 more
Exception running application sample.Main

Process finished with exit code 1

I can't find any solution for this. Can anybody help?

Answer 1

Finally I have worked the problem out.

I put the line:
--module-path /home/leo/MyApps/javafx-sdk-13.0.1/lib --add-modules=javafx.controls,javafx.fxml
here:
Run > Edit Configuration > VM options

and:
File > Project structure > Libraries > + choose the directory:
/home/leo/MyApps/javafx-sdk-13.0.1/lib

Answer 2

You used

Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));

Try:

Parent root = FXMLLoader.load(getClass().getResource("/sample.fxml"));