javafx - JavaFX8 fxml naming of nested controllers

Question

Given an .fxml include like:

<fx:include fx:id="header" source="Header.fxml" />

The Java FXML docs say to create two variables like:

@FXML private HBox header;
@FXML private HeaderController headerController;

What determines the controller variable name? Is it always just the include id followed by "Controller"?

Answer 1

Yes the field name the controller is injected to is always constructed by concatenating the fx:id of the <fx:include> tag with "Controller".

It's "hidden" in the documentation of the FXMLLoader.CONTROLLER_SUFFIX field.

A suffix for controllers of included fxml files. The full key is stored in namespace map.

(The namespace map contains all the objects by the field name they are injected to, if such a field exists.)

You can verify that it's value is "Controller" here: https://docs.oracle.com/javase/8/javafx/api/constant-values.html#javafx.fxml.FXMLLoader.CONTROLLER_SUFFIX