fxinclude

fx:include is an element in JavaFX’s FXML language used to embed another FXML file inside a parent document. When the parent is loaded by FXMLLoader, the included file is loaded as well and its root node is inserted into the scene graph at the position of the fx:include tag. This supports modular UI design by reusing components.

Syntax and usage: The element is written as <fx:include source="path/to/file.fxml"/> within an FXML file. The source attribute specifies the path to the external FXML and is resolved relative to the including file. You can optionally assign an fx:id to the fx:include for referencing the included root from a controller, and you may access the included root’s API through its own controller if one is defined in the included file.

Controllers and scope: The included file may declare its own fx:controller, giving it independent behavior and lifecycle from the parent. The parent and included controllers can interact through the included root node or via public methods exposed on the included controller. Nested fx:include elements are supported, enabling deeper composition.

Limitations and behavior: Circular includes can cause load failures; the included file should define a valid root node. Path resolution follows standard URL resolution rules. If loading the included file fails, an exception is raised during FXMLLoader.load.

Example usage: place <fx:include source="Header.fxml"/> in a parent layout where Header.fxml defines the header structure and its own controller if needed. fx:include provides a straightforward way to compose complex user interfaces from reusable components while maintaining separate concerns for each FXML file.