JavaFX从主类调用控制器方法

Question

I have a little problem with my JavaFX Application, I want to call a method in a controller from the main Class but it does not work.

I tried this Accessing FXML controller class and this How do I access a UI element from another controller class in JavaFX?

But it does not work.

So, in my Application I have a main window and from there I can open a second window, when I close the second window I want to call a method in the main controller for updating some elements..

My main class have this two Windows:

@Override
public void start(Stage primaryStage) throws IOException {
    this.primaryStage = primaryStage;
    mainWindow();

public void mainWindow() {
    try {
        FXMLLoader loader = new FXMLLoader(MainApp.class.getResource("/App.fxml"));
        Parent root = loader.load();
        AppController appController = loader.getController();
        appController.setMain(this);
        Scene scene = new Scene(root);
        primaryStage.setScene(scene);
        primaryStage.show();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public void secondWindow() throws IOException {
    try {
        FXMLLoader loader = new FXMLLoader(getClass().getResource("SecondWindow.fxml"));
        Parent root = loader.load();
        Stage stage = new Stage();
        SecondWindowController secondWindowController = loader.getController();
        secondWindowController.setStage(stage);
        stage.initOwner(primaryStage);
        stage.initModality(Modality.WINDOW_MODAL);
        stage.setScene(new Scene(root));
        stage.show();
        stage.setOnCloseRequest(event -> {
            event.consume();
            Alert alert = new Alert(Alert.AlertType.CONFIRMATION);
            alert.setHeaderText("close?");
            alert.initOwner( stage);
            Optional<ButtonType> result = alert.showAndWait();
            if (result.get() == ButtonType.OK){

            // Here I want to call the method to update in the AppController

                stage.close();
            }
        });

    } catch (Exception e) {
        e.printStackTrace();
    }
}

Is there a way to call the method there?

Answer 1

Your secondWindow() method is never called.

When you do call it, just pass the reference to the appController, which you already retrieved from the FXML via AppController appController = loader.getController(); , to the method which creates the new window.

Change the signature of:

secondWindow()

to:

secondWindow(final AppController appController)