Not loading children nodes in layout javafx - spring

Question

I'm trying to do a simple startup window for my application.
ClassLoader cachingClassLoader = new MyClassLoader(FXMLLoader.getDefaultClassLoader());
URL resource = MainApp.class
.getResource("/startupWindow.fxml").toURI().toURL();
FXMLLoader loader = new FXMLLoader(resource);
loader.setClassLoader(cachingClassLoader);
BorderPane rootLayout = (BorderPane) loader.load();
scene = new Scene(rootLayout,512,384);
this.primaryStage.initStyle(StageStyle.UNDECORATED);
this.primaryStage.setTitle(TITLE);
this.primaryStage.setScene(scene);
this.primaryStage.show();
//configuration main layout and add it to the stage
Unfortunately, after the start, application shows up startup window, however without any content. Throughout the loading of the main layout the startup window content is empty. Besides I had no exceptions.
I noticed that the problem with the content loading occurs when additional code is after the calling primaryStage.show(). And a content of layout is rendered at the end of additional code, for example:
this.primaryStage.setScene(scene);
this.primaryStage.show();
Thread.sleep(2000L);
// Content is displayed,( after 2 seconds ).
I have no idea how to make it work. Any advices will be helpful.
EDIT:
The issue I'm actually facing is create a startup window while loading Spring application context. I've been trying to create application context in separate Thread and it just hangs up with no exception occuring.
EDIT 2:
After some debugging I've found an exception:
org.springframework.beans.factory.BeanCreationException:
Error creating bean with name 'SomePresenter': Invocation of init method failed;
nested exception is java.lang.IllegalStateException:
Not on FX application thread; currentThread = Thread-3
By the way, application follows MVP design pattern and Spring application context loads automatically views and presenters.
EDIT 3:
The piece of code where I create new thread is:
Task loadingTask = new Task() {
#Override
protected ApplicationContext call() throws Exception {
return new ClassPathXmlApplicationContext("./spring/application_context.xml");
}
};
loadingTask.setOnSucceeded(event -> {
context = (ApplicationContext)loadingTask.getValue();
MainPresenter mainPresenter = (MainPresenter) context.getBean("MainPresenter");
mainPresenter.getView().setPrimaryStage(primaryStage);
scene = new Scene(mainPresenter.getView(), bounds.getWidth(), bounds.getHeight());
scene.getStylesheets().add(getClass().getResource("/styles/styles.css").toExternalForm());
this.primaryStage.setScene(scene);
});
new Thread(loadingTask).start();

Answer 1

The start() method is executed on the FX Application Thread, which is the thread responsible for rendering the UI and processing user input. It is also the only thread on which some actions are legal, such as accessing the state of nodes in the scene graph and creating Scenes and Stages.
The problem is that you are executing code that blocks this thread, meaning that the UI doesn't have a chance to be rendered. If you have time-consuming (non-UI) code to execute, you should execute that in a separate thread, and then when that is complete schedule an update to happen to the UI on the FX Application thread.
The Task class is designed for this use case.
So you can do something like this:
public void start(Stage primaryStage) {
primaryStage.initStyle(StageStyle.UNDECORATED);
primaryStage.setTitle(TITLE);
primaryStage.setScene(scene);
primaryStage.show();
Task<SomeDataType> startupTask = new Task<SomeDataType>() {
#Override
protected SomeDataType call() {
SomeDataType result = ... ; // result of time-consuming operation
return result ;
}
};
startupTask.setOnSucceeded(event -> {
// this is executed on the FX Application Thread
SomeDataType result = startupTask.getValue();
// update UI using result ...
});
new Thread(startupTask).start();
}

Answer 2

If possible, you should check the EAP of JDK 1.8.0_40 as it enables you to build UI in background tasks as far as I understand what they are trying to do (out of JavaFX Application Thread):
See their JIRA:
https://javafx-jira.kenai.com/browse/RT-17716
Building UI in background tasks does make sense in some cases, especially with big FXML files as it is quite slow.
If does not solve your problem, you will have to check your Spring integration, are you using a custom FXMLLoader with a builder factory / controller factory? Does Spring run in a separate thread or in JavaFX Application Thread?