JavaFX Application Thread Mysteriously Disappearing in Netbeans RCP / JavaFX App

I have a fair amount of pluggable infrastructure in place with the NetBeans platform for trading related applications. My latest application, “Atlas Trader” is being used to route our commodity trades through Quantitative Brokers. I want to take advantage of JavaFX for this project as it provides a cleaner MVC separation than Swing does, and also provides a lot of eye candy out of the box, such as animated transitions, translucency, etc.). I have been having strange issues however when attempting to incorporate this as a module to my NetBeans platform application.

I started out with a stripped down version of the platform, since I don’t need any of the Swing components and all the UI components with be within an JavaFX Scene, so have only included the following RCP modules:

  • org-netbeans-api-annotations-common
  • org-openide-modules
  • org-openide-util
  • org-openide-util-lookup

In my module’s “Installer” class, the restored() method kicks off the JavaFX app with the following calls:


Screen Shot 2015-04-10 at 11.07.51 AM

All seems to be ok at this point. The app launches and displays the UI correctly. I can log in and get to the main screen of the application.

Below is the main screen in the application. The issues arrises when one of the commodity labels at the top of the screen is clicked. The expected behaviour is to display a new JavaFX componenet allowing the user to enter an order.

Screen Shot 2015-04-10 at 11.13.21 AM

The “CommodityHeaderLabels” at the top of the UI have the following action method defined.

public void fireCommodityClicked() {

When one of these headers are clicked, an exception is immediately thrown, complaining that:

Caused by: javafx.fxml.LoadException: 


at javafx.fxml.FXMLLoader.constructLoadException(
at javafx.fxml.FXMLLoader.loadImpl(
at javafx.fxml.FXMLLoader.loadImpl(
at javafx.fxml.FXMLLoader.load(
at com.zoicapital.qtrader.plugin.TradePanel.init(
... 10 more

Caused by: java.lang.NullPointerException
at javafx.fxml.FXMLLoader.loadTypeForPackage(

After drilling into the FXMLLoader class to find out what was going on, it appears that the “fireCommodityClick()” method is not being called from the JavaFX Event thread, and so it isn’t able to load the FXML file for the component that it needs to create when the item is clicked.

In fact, when running through the debugger, the JavaFX Thread is running prior to the component being clicked, but disappears when the component is clicked.

To make things even more difficult to understand, is that all the events leading up to this point are executed as expected in the RCP version of this application on the Java FX Application Thread. As I mentioned, I can log in to the application without any issues, and its not until one of these CommodityLabel components are clicked that the issue appears. Below is a screenshot of NB in the debugger with a breakpoint at the first line in the method that is called when the component is clicked. On the left side of the screen you can see the stack trace and that the current thread is the “AppKit Thread”, with the Java FX Application thread no longer present.

NB Screenshot

I set up a test project to run this application as a stand-alone outside of the NetBeans RCP, and things work as expected. The event method is called on the JavaFX Application Thread, and the resulting component is created and displayed as expected.

I can only think that there is an exception being swallowed somewhere, and that there may possibly be another NetBeans Platform module that is required in addition to the 4 modules that I mentioned at the beginning of this post.

I realize this post is a little short on the amount of code, but I’m looking for any other ideas on areas I could look at to further debug this issue.

twitter: @RobTerpilowski

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