[FIXED] Trying to run javaFX on java sdk 15 with the module from javaFX 15 in IntelliJ

Issue

This is the error, however it only occurs when using the Button class.

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:64)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    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:64)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:564)
    at java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1071)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195)
    at java.base/java.lang.Thread.run(Thread.java:832)
Caused by: java.lang.IllegalAccessError: superclass access check failed: class com.sun.javafx.scene.control.ControlHelper (in unnamed module @0x5b3ec5dc) cannot access class com.sun.javafx.scene.layout.RegionHelper (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.scene.layout to unnamed module @0x5b3ec5dc
    at java.base/java.lang.ClassLoader.defineClass1(Native Method)
    at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
    at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
    at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:825)
    at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:723)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:646)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:604)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:168)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:522)
    at javafx.scene.control.Control.<clinit>(Control.java:86)
    at Main.start(Main.java:17)
    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)
Exception running application Main

This is the code

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class Main extends Application{

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

    @Override
    public void start(Stage stage) throws Exception {
        Button button = new Button();
        button.setText("Click Me");
        stage.setTitle("First JavaFX GUI");

        StackPane layout = new StackPane();
        layout.getChildren().add(button);

        Scene scene = new Scene(layout, 300, 250);
        stage.setScene(scene);
        stage.show();
    }
}

When I remove the Button, it runs fine and shows the window, however when using Button it throws that error. How can I solve this. I am currently in a Mac, using IntelliJ. JDK 15 with JavaFX 15.

Solution

If you are using IntelliJ you should add this to the VM options under the Run Configurations. --module-path PathToJavaFX --add-modules javafx.controls,javafx.fxml.

the PathToJavaFx should be the /lib folder.

Answered By - VoidNull