This post is written as 6th in JavaFX Advent Calendar 2012.

JavaFX application runs also as Java applet and java web start.
With javafxpackager, you can make executable jar, applet, java web start.

However, there was a small trap, I was trapped, I write about it.

Since I made presentation document for the 8th JavaFX workshop, I was trying to publish it as an applet.
However, the applet did not run. I look at the Java console, the error seems to have occurred in the load method of FXMLLoader.

I think I will look at the source of OpenJFX, but there was no
Is not been publishing all the source of OpenJFX?

Since it can not be helped, I was looking closely at the stack trace once more, getDeclaredFields method have failed due to security.
When I look further, which line of FXML file is invalid, it was written to the error message. So when I try to check inside FXML, "fx:id" attribute is doubtful.

It seems to be an error because it uses the getDeclaredFields method in the process of setting a field of the controller class, an instance of the Control that has the fx:id attribute.
I think so, the application using FXML would not be able to run most of the time.I have heard it is okay that @FXML field is private.
However, if @FXML field is public, can access it by getFields method, and no problem in terms of security.That means, I think this is a bug.
If the applet is signed, then it probably runs. But I think the signature is required is not good.

When I examine, it seemed to be registered as a bug in JIRA. RT-23622
However, Fix Version/s is "Lombard", they won't fix it until JavaSE8?

So, (it isn't much sense) I tried to display only Label, but there was a further trap.

Using SceneBuilder, I operated

Put Label -> Change Font -> Copy & Paste

then, same error occured.
When I look at FXML, Label tag which was copied had font attribute like font="$x1", and original Label tag has fx:id attribute like fx:id="x1".
If JavaFX Control having a child tag is copied, the child tag automatically create fx:id attribute?
Then, Although I am not supposed to create fx:id attribute, same error occured.

In conclusion, if you want to run the application using FXML as Applet, we seem to be (almost) the signature is a requirement. (And perhaps JavaWebStart)
I hope that they fix this bug at JavaFX2.2 minor version up...