Using SceneBuilder to Create a User Interface - JavaFX 8: A Definitive Guide to Building Desktop, Mobile, and Embedded Java Clients - page 90

handlers are also hooked up. The load() method returns the top-level object in the FXML file, which in our example
is a Group . This returned Group object is assigned to the rootGroup variable and is used in subsequent code the same
way as the programmatically created rootGroup in Chapter 2 is used. We then call the getController() method to
get the controller with its node fields already injected by the FXMLLoader . This controller is assigned to the controller
variable and is used in subsequent code as if we have just created it and assigned its node fields programmatically.
Now that we've finished switching the Stage Coach program from programmatic to declarative UI creation,
we can run it. It behaves just like in Chapter 2. Figure 3-3 shows the program running with the transparent
command-line argument.
Figure 3-3. The Stage Coach program run with transparent command-line argument
In this section we touched on all aspects of the FXML design-time and runtime facilities. However, we described
only parts of each facility, barely enough to get our example program going. In the rest of this chapter, we study each
of the facilities in detail.
Understanding the FXML Loading Facility
The FXML file loading facility is made up of two classes, an interface, an exception, and an annotation in the
javafx.fxml package. The FXMLLoader is the class that does the bulk of the work, such as reading and parsing
the FXML file, recognizing processing instructions in the FXML file, and responding with the necessary actions,
recognizing each element and attribute of the FXML file and delegating the object creation tasks to a set of builders,
creating the controller object if necessary and injecting the nodes and other objects into the controller. The
JavaFXBuilderFactory is responsible for creating builders in response for FXMLLoader 's requests for builders for a
particular class. The Initializable interface can be implemented by controller classes to receive information from
the FXMLLoader as in previous versions of JavaFX; however, this functionality has been superseded by the injection
approach, so we do not discuss it. A LoadException is thrown if the FXML file contains errors that make it impossible
for the FXMLLoader to construct all the objects specified in the FXML file. The @FXML annotation can be used in
controller classes to mark certain fields as injection targets and certain methods as event handler candidates.