javafx 2 - How to pass object created in FXML Controller1 to Controller2 of inner FXML control

Question

I have a JavaFX 2.0 application, which consists of two FXML files, and two controllers for them + one "main" .java file.

At the start time, FXML1 is initialized, like this:

public void start(Stage stage) throws Exception {
    stage.setTitle("Demo Jabber JavaFX Chat");
    
    Parent root = FXMLLoader.load(getClass().getResource("fxml_example.fxml"),
        ResourceBundle.getBundle("fxmlexample.fxml_example"));        
    Scene scene = new Scene(root, 226, 264);
    stage.setScene(scene);
    scene.getStylesheets().add("fxmlexample/fxmlstylesheet.css");
    stage.show();
}

Then, when a button from scene1 is clicked, in its event handler in Controller1 class, I change scene1 root, to show new gui-view for a user. And in this controller I initialize some object. For example, like this:

public class FXMLExampleController {
   //some fields...
   private MySuperObject c;
   @FXML protected void handleSubmitButtonAction(ActionEvent event) {
    //some fields...
    c = new MySuperObject(); //here i initialize my object, i'm interested in
    try {
        c.login(username, password); // some actions with this object, which i need to make.
        Scene cc = buttonStatusText.getScene();
        Parent root = null;
        try {
            //changing a scene content...
            root = FXMLLoader.load(getClass().getResource("fxml_example2.fxml"),
            ResourceBundle.getBundle("fxmlexample.fxml_example"));
        } catch (IOException ex) {
            Logger.getLogger(FXMLExampleController.class.getName()).log(Level.SEVERE, null, ex);
        }
        cc.setRoot(root);
      }

And, after that, I have to do some work with that object on the next scene, and it must be NOT a new instance of the same class, but the object which I have initialized on the first one scene.

I understand how to make these all using "standard java", but I'm kind of confused on this task using JavaFX + FXML.

Answer 1

In FX 2.2 new API for controller-node was introduced:

// create class which is both controller and node
public class InnerFxmlControl extends HBox implements Initializable {
  @FXML public ComboBox cb;

  public InnerFxmlControl () {
     FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("fxml_example2.fxml"));
     fxmlLoader.setRoot(this);
     fxmlLoader.setController(this);
     try {
         fxmlLoader.load();            
     } catch (IOException exception) {
         throw new RuntimeException(exception);
     }
  }

with next fxml (note tag fx:root):

<fx:root type="javafx.scene.layout.HBox" xmlns:fx="http://javafx.com/fxml">
  <children>
    <ComboBox fx:id="cb" />
  </children>
</fx:root>

By this you've created a new control, which you can use as regular JavaFX controls. E.g. in your case:

@FXML protected void handleSubmitButtonAction(ActionEvent event) {
    // you just create new control, all fxml tricks are encapsulated
    InnerFxmlControl root = new InnerFxmlControl();
    // and you can access all its' methods and fields including matched by @FXML tag:
    root.cb.getItems().add("new item");

    Scene cc = buttonStatusText.getScene();
    cc.setRoot(root);
  }

and in fxml:

<InnerFxmlControl />