I’m making a simple game for my programming class, using JavaFX. Everything runs fine when I try it in Intelij, but when I try to export it to a jar file, I run into 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$2(LauncherImpl.java:196)
        at java.base/java.lang.Thread.run(Thread.java:1583)
Caused by: java.lang.IllegalAccessError: class com.sun.media.jfxmedia.locator.Locator (in unnamed module @0x491bcf8c) cannot access class com.sun.javafx.PlatformUtil (in module javafx.base) because module javafx.base does not export com.sun.javafx to unnamed module @0x491bcf8c
        at com.sun.media.jfxmedia.locator.Locator.<init>(Locator.java:235)
        at javafx.scene.media.Media.<init>(Media.java:392)
        at application.GridGame.start(GridGame.java:110)
        at application.Main.start(Main.java:17)
        at [email protected]/com.sun.javafx.application.LauncherImpl.lambda$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)
        at [email protected]/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at [email protected]/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:185)
        ... 1 more
Exception running application application.Main

I think it’s because of these lines of code, since it run fine when I commented the code.

String path = getClass().getResource("/ost.mp3").toString();
Media media = new Media(path);
MediaPlayer mediaPlayer = new MediaPlayer(media);
mediaPlayer.setCycleCount(MediaPlayer.INDEFINITE);
mediaPlayer.play();

The problem only happens when I try to use an mp3 file. All the other resources like images, gifs, and fonts from the same folder work fine.