fx:className attribute

The fx:className attribute controls the name of the generated class. If this attribute is not specified, the name of the generated class defaults to the standalone .fxml file name or the annotated Java class name, plus the Base suffix. For example, the default generated class name for MyControl.fxml will be MyControlBase.

In .fxml files, the fx:className attribute can only be used when the fx:subclass attribute is also specified.

Usage

com/sample/MyControl.fxml

<BorderPane xmlns="http://javafx.com/javafx" xmlns:fx="http://jfxcore.org/fxml/2.0"
            fx:subclass="com.sample.MyControl"
            fx:className="MyCustomBaseClass">
<BorderPane/>

com/sample/MyControl.java

public class MyControl extends MyCustomBaseClass {
    MyControl() {
        initializeComponent();
    }
}