Can't get JavaFX to run in Eclipse

Question

I have a Problem with JavaFX that I can't resolve after more than a day of researching on Google and different forums. I am currently learning Java with a tutorial and a few books, which has been going very nicely up until now.

My problem is that I can't get JavaFX to run in eclipse. I have installed the e(fx)clipse addon.

I have made sure that the JavaFX SDK is listed in the Libraries in the Java Buid Path and I tried opening a new JavaFX Project, but whatever I do I always get "the import javafx can't be resolved".

I have tried all of this with the Java JDK 12 on Ubuntu 18.04 (my main system) and Win 8.1.

Has anybody here an idea what could be wrong?

Edit:

This is the import statement:

import javafx.application.Application;

This is the Code of my Class (although i also tried the auto generated "Main" Class from the Eclipse JavaFX Project):

import javafx.application.Application;
import javafx.stage.Stage;

public class JvaFXDemo extends Application{

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

    @Override
    public void start(Stage primaryStage) throws Exception{
        primaryStage.show();
    }
}

Now i was able to get rid of this Error by creating a Class named "module-info.java" in the "scr" Folder that contains this Code:

requires javafx.base;
requires javafx.controls;
requires javafx.fxml;
requires javafx.graphics;
requires javafx.media;
requires javafx.swing;
requires javafx.swt;
requires javafx.web;

Eclipse doesn't show any Errors in the Code now, but when i try to compile it i get a massive Exception:

Exception in Application constructor
Exception in thread "main" 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 java.base/sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:1051)
Caused by: java.lang.RuntimeException: Unable to construct Application instance: class application.Main
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:890)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195)
    at java.base/java.lang.Thread.run(Thread.java:835)
Caused by: java.lang.IllegalAccessException: class com.sun.javafx.application.LauncherImpl (in module javafx.graphics) cannot access class application.Main (in module BlaBla) because module BlaBla does not export application to module javafx.graphics
    at java.base/jdk.internal.reflect.Reflection.newIllegalAccessException(Reflection.java:376)
    at java.base/java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:639)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:490)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:481)
    at javafx.graphics/com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$8(LauncherImpl.java:802)
    at javafx.graphics/com.sun.javafx.application.PlatformImpl.lambda$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)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at javafx.graphics/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
    ... 1 more

Answer 1

So if everything is correct with your jar and you have correctly included it, it can be pretty hard to find the bug. How big is your project? If I were you, I'd create a Maven project from your project instead of including the jar manually. This will also save you a lot of work when adding more dependencies.

Here you can find all javafx dependencies: https://mvnrepository.com/artifact/org.openjfx

I integrated javafx13 into my modularized project. The corresponding dependency only has to be imported into the POM and then you have to import the necessary requirements into your module-info.java (as you did before).

Answer 2

In your module-info.java file, you should add:

opens 'your main class package';

You can follow this online tutorial: https://www.youtube.com/watch?v=B-mgPyXEIgo

As an advise, you shouldn't use IDE add-ons for JavaFx like e(fx)clipse. Running JavaFx has changed a lot and these add-ons are not up to date.