Communicating with an FXML Controller that's already open

Question

I have searched again and again on this to no avail. I have a JavaFX FXML window which is connected to a Controller; this window is open. Clicking a button on the window triggers the opening of another FXML file, linked to its respective controller.

The second window (optionsUI.fxml and optionsController) has a few radio buttons. When one is clicked, I want the location of an image/button to change in the mainUI window. How do I go about doing that?

mainController:

public void assetPressed(MouseEvent event) {
        //Get the source of Handler
        HUDButton button = (HUDButton) event.getSource();

        //Check if an asset is already selected
        //----do a thing
            //Open stage
            openStage(currentAsset);

        } else {
            //if the current asset selected and the new asset clicked are the same
            //----do something
                closeStage();
            }
            //if the current asset selected and the new asset clicked are different
            else {
                //----do something else
                assetIsSelected = true;
                openStage(currentAsset);
            }
        }
    }
//opening optionsUI.fxml
public void openStage(Asset asset) {

        FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("optionsUI.fxml"));

        Parent root = null;
        try {
            root = fxmlLoader.load();
        } catch (IOException e) {
            e.printStackTrace();
        }
        optionsController controller = fxmlLoader.getController();

        Scene scene = new Scene(root, 300, 450);
        stage.setScene(scene);
        if (alreadyExecuted == false) {
            stage.initStyle(StageStyle.UNDECORATED);
            stage.initOwner(stageControls); //Making the mainUI the owner of the optionsUI
            stage.setTitle("HUDEdit Version 3.0.0");
            alreadyExecuted = true;
        }

The main issue I am having is adding an event handler on the radio buttons which will change a property of the Button that was pressed (currentButton). I searched on this issue, but what I got was what I have already done: to open a new stage with the new values present in the other FXML file.

Answer 1

You can do something like this in your OptionsController (I am going to rename things to conform to standard naming conventions, btw.)

The basic idea here is just to expose a property representing what the user has selected via the radio buttons.

public class OptionsController {

    @FXML
    private RadioButton radioButton1 ;

    @FXML
    private RadioButton radioButton2 ;

    private SomeType someValue1 = new SomeType();
    private SomeType someValue2 = new SomeType();

    private final ReadOnlyObjectWrapper<SomeType> selectedThing = new ReadOnlyObjectWrapper<>();

    public ReadOnlyObjectProperty<SomeType> selectedThingProperty() {
        return selectedThing.getReadOnlyProperty() ;
    }

    public final SomeType getSelectedThing() {
        return selectedThingProperty().get();
    }

    public void initialize() {
        radioButton1.selectedProperty().addListener((obs, wasSelected, isNowSelected) -> {
            if (isNowSelected) {
                selectedThing.set(someValue1);
            }
        });
        radioButton2.selectedProperty().addListener((obs, wasSelected, isNowSelected) -> {
            if (isNowSelected) {
                selectedThing.set(someValue2);
            }
        });
    }

    // ...
}

And now when you load Options.fxml you can just observe that property and do whatever you need when it's value changes:

public void openStage(Asset asset) {

    FXMLLoader fxmlLoader = new FXMLLoader(getClass().getResource("optionsUI.fxml"));

    Parent root = null;
    try {
        root = fxmlLoader.load();
    } catch (IOException e) {
        e.printStackTrace();
    }
    OptionsController controller = fxmlLoader.getController();
    controller.selectedThingProperty().addListener((obs, oldSelection, newSelection) -> {
        // do whatever you need with newSelection....
    });

    // etc...
}