Include FXML throws Exception from .jar

I am trying to include an fxml file in another one and deploy my application as a runnable jar.

The top-level fxml file is loaded like this:

URL location = Editor.class.getClassLoader().getResource("view/app.fxml");
FXMLLoader fxmlLoader = new FXMLLoader(location);
Parent root = fxmlLoader.load();
appController = fxmlLoader.getController();

app.fxml, which is located in "src/view" contains this line:

<fx:include fx:id="console" source="console.fxml" />

Running this in eclipse will work as expected, but running the exported .jar file will print:

Exception in Application start method
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:566)
        at org.eclipse.jdt.internal.jarinjarloader.JarRsrcLoader.main(JarRsrcLoader.java:61)
Caused by: java.lang.RuntimeException: Exception in Application start method
        at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:900)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$2(LauncherImpl.java:195)
        at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: javafx.fxml.LoadException:
view/app.fxml:92

        at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2625)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2603)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2466)
        at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2435)
        at de.hsa.dice.editor.Editor.start(Editor.java:49)
        at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$9(LauncherImpl.java:846)
        at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$12(PlatformImpl.java:455)
        at com.sun.javafx.application.PlatformImpl.lambda$runLater$10(PlatformImpl.java:428)
        at java.base/java.security.AccessController.doPrivileged(Native Method)
        at com.sun.javafx.application.PlatformImpl.lambda$runLater$11(PlatformImpl.java:427)
        at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:96)
        at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
        at com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:174)
        ... 1 more
Caused by: java.net.MalformedURLException: Could not open InputStream for URL 'rsrc:console.fxml'
        at org.eclipse.jdt.internal.jarinjarloader.RsrcURLConnection.getInputStream(RsrcURLConnection.java:49)
        at java.base/java.net.URL.openStream(URL.java:1117)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2465)
        at javafx.fxml.FXMLLoader.access$2700(FXMLLoader.java:105)
        at javafx.fxml.FXMLLoader$IncludeElement.constructValue(FXMLLoader.java:1154)
        at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:754)
        at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2722)
        at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2552)
        ... 12 more

Note that the console.fxml file is in the same package as app.fxml (in both the IDE and the .jar file). That's why I also tried source="./console.fxml", but nothing changed.

Solution

I found the reason and a workaround for this issue.

The javafx.fxml.FXMLLoader class uses this URL constructor, when creating the FXMLLoader for included fxml files:

public URL(URL context, String spec)

using the location from the FXMLLoader(location) constructor as context and using the "source" from the include-element as spec.

So when loading my root fxml file with the path "view/app.fxml", the context will be the "view" package in my IDE, while it will be the root of the classpath in the exported .jar.

I tried creating the app-URL with

URL classpath = getClass().getProtectionDomain().getCodeSource().getLocation();
URL location = new URL(classpath, "view/app.fxml");

but my context will not be used again when this is plugged into the same constructor again later by the FXMLLoader.

So the only workaround I could think of is to just put all fxml-files (at least those with an include tag) into the root of a source-folder. That way, it will be located directly at the classpath in any environment.