I just started JavaFX and I when I added my button method, I get a start method error. Anyone help?

[Luka Sarich]

I'm running JDK 12. I appreciate anyone taking time out of their day to look this over and help me out! Thanks!!

This is my code :

package sample;

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.text.Text;
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"));
        Group root = new Group();
        Text txt = new Text("Sup?");
        Button btn = new Button();
        btn.setText("Say Sup!");
        txt.setY(50);
        root.getChildren().add(txt);
        root.getChildren().add(btn);
        primaryStage.setTitle("Sup");
        primaryStage.setScene(new Scene(root, 300, 275));
        primaryStage.show();
    }


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

And then this is the error that gets thrown :

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$2(LauncherImpl.java:195)
    at java.base/java.lang.Thread.run(Thread.java:835)
Caused by: java.lang.IllegalAccessError: superclass access check failed: class com.sun.javafx.scene.control.ControlHelper (in unnamed module @0x3a38f132) cannot access class com.sun.javafx.scene.layout.RegionHelper (in module javafx.graphics) because module javafx.graphics does not export com.sun.javafx.scene.layout to unnamed module @0x3a38f132
    at java.base/java.lang.ClassLoader.defineClass1(Native Method)
    at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
    at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
    at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:802)
    at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:700)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:623)
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
    at javafx.scene.control.Control.<clinit>(Control.java:86)
    at sample.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$10(PlatformImpl.java:428)
    at java.base/java.security.AccessController.doPrivileged(AccessController.java:389)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
    at javafx.graphics/com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
Exception running application sample.Main

[John Damien Smith]

I haven't used JDK 12.  These kind of module errors don't occur in JDK 8 as that does not have modules, but that is old and outdated so it is better to get the modular system in JDK 12 to work.

Take a look at:
https://stackoverflow.com/questions/54291958/javafx-11-illegalaccesserror-when-creating-label
There is says:
"you need to set the required VM options for your project"

-p /usr/lib/jvm/javafx-sdk-11.0.2/lib --add-modules javafx.controls

I haven't got a copy of JDK 12 locally to try it at the moment, but you could try giving it a go.

[Luka Sarich]

John Damien Smith wrote:I haven't used JDK 12.  These kind of module errors don't occur in JDK 8 as that does not have modules, but that is old and outdated so it is better to get the modular system in JDK 12 to work.

Take a look at:
https://stackoverflow.com/questions/54291958/javafx-11-illegalaccesserror-when-creating-label
There is says:
"you need to set the required VM options for your project"

-p /usr/lib/jvm/javafx-sdk-11.0.2/lib --add-modules javafx.controls

I haven't got a copy of JDK 12 locally to try it at the moment, but you could try giving it a go.

Thanks so much! I played with the VM settings and got it working.. I've been stuck on this for a couple days now and just now decided to ask on here. i shouldve done it along time ago. Thanks for helping me out!!