I have created an FXML-based custom control, which in turn references another FXML-based custom control. They all work just fine when I load them in eclipse, but when I try to import them into SceneBuilder, the outer control (the one containing the other one) does not get imported properly.
Here is a dramatically simplified example:
Widget.java:
package example;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.fxml.FXMLLoader;
import javafx.scene.layout.Pane;
public class Widget extends Pane{
public Widget() {
Logger logger = Logger.getLogger(Widget.class.getName());
try {
FXMLLoader loader= new FXMLLoader(Widget.class.getResource("Widget.fxml"));
Pane pane = loader.load();
this.getChildren().add(pane);
}
catch(Exception e) {
logger.log(Level.SEVERE, "Failed to load Widget", e);
}
}
}
Widget.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.FlowPane?>
<?import javafx.scene.control.Label?>
<?import example.SubWidget?>
<FlowPane xmlns:fx="http://javafx.com/fxml/1" >
<children>
<Label text="Widget"/>
<SubWidget></SubWidget>
</children>
</FlowPane>
SubWidget.java:
package example;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.fxml.FXMLLoader;
import javafx.scene.layout.Pane;
public class SubWidget extends Pane{
public SubWidget() {
Logger logger = Logger.getLogger(SubWidget.class.getName());
try {
FXMLLoader loader= new FXMLLoader(SubWidget.class.getResource("SubWidget.fxml"));
Pane pane = loader.load();
this.getChildren().add(pane);
}
catch(Exception e) {
logger.log(Level.SEVERE, "Failed to load SubWidget", e);
}
}
}
SubWidget.fxml:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.layout.FlowPane?>
<?import javafx.scene.control.Label?>
<FlowPane xmlns:fx="http://javafx.com/fxml/1" >
<children>
<Label text="Subwidget"/>
</children>
</FlowPane>
I export these to a jar and attempt to import them via SceneBuilder's jar import functionality. When I do so, SubWidget gets imported and looks just fine. Widget will also show up as a control, but it will be completely empty.
When I check the log files I see that it is due to the FXML loader not being able to find the SubWidget class file:
Oct 29, 2020 4:28:30 PM example.Widget <init>
SEVERE: Failed to load Widget
javafx.fxml.LoadException:
file:/C:/Users/nate/AppData/Roaming/Scene%20Builder/Library/TestFxControl.jar!/example/Widget.fxml
at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2601)
at javafx.fxml.FXMLLoader.importClass(FXMLLoader.java:2848)
at javafx.fxml.FXMLLoader.processImport(FXMLLoader.java:2692)
at javafx.fxml.FXMLLoader.processProcessingInstruction(FXMLLoader.java:2661)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2517)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2409)
at example.Widget.<init>(Widget.java:27)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at sun.reflect.misc.ReflectUtil.newInstance(Unknown Source)
at javafx.fxml.FXMLLoader$InstanceDeclarationElement.constructValue(FXMLLoader.java:1009)
at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:746)
at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2707)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2425)
at com.oracle.javafx.scenebuilder.kit.library.util.JarExplorer.instantiateWithFXMLLoader(JarExplorer.java:110)
at com.oracle.javafx.scenebuilder.kit.library.util.JarExplorer.exploreEntry(JarExplorer.java:160)
at com.oracle.javafx.scenebuilder.kit.library.util.JarExplorer.explore(JarExplorer.java:70)
at com.oracle.javafx.scenebuilder.kit.library.user.LibraryFolderWatcher.exploreAndUpdateLibrary(LibraryFolderWatcher.java:325)
at com.oracle.javafx.scenebuilder.kit.library.user.LibraryFolderWatcher.runDiscovery(LibraryFolderWatcher.java:138)
at com.oracle.javafx.scenebuilder.kit.library.user.LibraryFolderWatcher.run(LibraryFolderWatcher.java:92)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: example.SubWidget
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at javafx.fxml.FXMLLoader.loadTypeForPackage(FXMLLoader.java:2916)
at javafx.fxml.FXMLLoader.loadType(FXMLLoader.java:2905)
at javafx.fxml.FXMLLoader.importClass(FXMLLoader.java:2846)
... 24 more
It appears to me that the FXML loader is using a classloader which doesn't include other custom components, which is odd because if I bypassed the FXML in the Widget class and made it:
public class Widget extends FlowPane{
public Widget() {
this.getChildren().addAll(new Label("Widget"), new SubWidget());
}
}
Then it loads just fine in SceneBuilder. So it appears that the ClassLoader that actually loads Widget and the one that the FXMLLoader uses are not the same.
This could possibly be related to this unanswered question, though they aren't exactly the same thing.
I had the same issue and created a work around that is not pretty but works.
Create a jar that contains blank classes for the controls you can not load into Scene Builder, e.g:
package com.junglefinance.gui.controls;
import javafx.fxml.FXML;
import javafx.scene.control.TextField;
public class CategoryTextField extends TextField {
@FXML private TextField textField;
public CategoryTextField() {
}
}
Make sure the package matches the package of your target control.
Load this jar into Scene Builder. This will allow Scene Builder to generate your FXML ready to load into your program. When it is loaded it will pick up your target control rather than the dummy as the import is (in this case)
<?import com.junglefinance.gui.controls.CategoryTextField?>
Note the package.