JavFX FXML Loading Error (Nullpointerexception)

Question

Yeah i know this question has often been asked, i used the searching function but couldl'nt solve my problem with these answers, and now im tired to search at google or anywhere else.

My Problem: I try to load an FXML File into my Javacode:

public class Main extends Application {

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

@Override
public void start(Stage primaryStage) throws Exception {
    try {

        //Layout laden
        Pane pane = FXMLLoader.load(getClass().getResource("layout/main_layout.fxml"));

        //Scene erstellen und initialisieren
        Scene scene = new Scene(pane);
        scene.getStylesheets().add(getClass().getResource("css/main_layout.css").toExternalForm());
        primaryStage.setScene(scene);

        //Breite und Höhe der Stage setzen
        primaryStage.setWidth(1024);
        primaryStage.setHeight(768);

        primaryStage.setTitle("Untitled - jNotepad");

        primaryStage.show();
    } catch(IOException e) {
        e.printStackTrace();
    }
}
}

My FXML file is in the package de.toxiclab.jNotepad.layout, that means realtive to the path in layout/main_layout.fxml, so the path has to be correct.

And then it prints me this ugly exception:

javafx.fxml.LoadException: /J:/Eclipse%20Workspace/jNotepad/bin/de/toxiclab/jNotepad/layout/main_layout.fxml:19

at javafx.fxml.FXMLLoader.constructLoadException(FXMLLoader.java:2617) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2595) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2441) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3230) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3191) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3164) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3140) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3120) at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3113) at de.toxiclab.jNotepad.Main.start(Main.java:32) at com.sun.javafx.application.LauncherImpl$8.run(LauncherImpl.java:837) at com.sun.javafx.application.PlatformImpl$7.run(PlatformImpl.java:335) at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:301) at com.sun.javafx.application.PlatformImpl$6$1.run(PlatformImpl.java:298) at java.security.AccessController.doPrivileged(Native Method) at com.sun.javafx.application.PlatformImpl$6.run(PlatformImpl.java:298) at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95) at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at com.sun.glass.ui.win.WinApplication.access$300(WinApplication.java:39) at com.sun.glass.ui.win.WinApplication$4$1.run(WinApplication.java:112) at java.lang.Thread.run(Thread.java:744) Caused by: java.lang.NullPointerException at de.toxiclab.jNotepad.NotepadController.getStage(NotepadController.java:199) at de.toxiclab.jNotepad.NotepadController.(NotepadController.java:45) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:408) at java.lang.Class.newInstance(Class.java:433) at sun.reflect.misc.ReflectUtil.newInstance(ReflectUtil.java:51) at javafx.fxml.FXMLLoader$ValueElement.processAttribute(FXMLLoader.java:932) at javafx.fxml.FXMLLoader$InstanceDeclarationElement.processAttribute(FXMLLoader.java:976) at javafx.fxml.FXMLLoader$Element.processStartElement(FXMLLoader.java:216) at javafx.fxml.FXMLLoader$ValueElement.processStartElement(FXMLLoader.java:738) at javafx.fxml.FXMLLoader.processStartElement(FXMLLoader.java:2723) at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2527) ... 19 more

But i dont understand, why theres an damn Nullpointerexception, the PATH is 100% correct.

If I had to guess, it's trying to grab the window before the scene is completely shown, which is causing your null-pointer exception, you might have to add a WindowEvent.WINDOW_SHOWN handler to the stage in that point and then try to get the window once it's shown — WillBD

WillBD WillBD · Accepted Answer · 2014-04-30T21:45:06

So after seeing the error seemingly centering around the controller class 'NotePadController' I believe the reason you are seeing this NullPointerException is due to the fact that the nodes haven't been attached to the scene yet. In light of this, you may want to try attaching a WindowEvent.WINDOW_SHOWN handler onto that point in the method.

for example:

you mentioned that line 199 was return ((Stage)this.textPane.getScene().getWindow());

perhaps, instead, it would be better to have a static Window variable (say called 'window' ) and say:

(Stage)this.addEventHandler(WindowEvent.WINDOW_SHOWN, new EventHandler<WindowEvent>() {
            @Override
            public void handle(WindowEvent event) {
                window = ((Stage)this.textPane.getScene().getWindow());
            }
 });

or something along those lines.

It's also possible the main meat of the error is coming from somewhere else. Good luck! sometimes these types of problems can be a touch tricky.

JavFX FXML Loading Error (Nullpointerexception)

1 Answers