mainController.getMainApp().launch(MainApp.class);

@Override
public void start(Stage primaryStage) {
    this.primaryStage = primaryStage;
    this.primaryStage.setTitle("CLS");
    this.primaryStage.initStyle(StageStyle.UNDECORATED);
    // here the page fxml to load

public static void launch(Class<? extends Application> appClass, String... args)

launch(MainApp.class, "--FXMLFile=Sample.fxml", "UnnamedArgument");

Parameters parameters = getParameters();
List<String> unnamed = parameters.getUnnamed();
Map<String, String> named = parameters.getNamed();
List<String> raw = parameters.getRaw();