import java.io.IOException;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class App extends Application {

    private static Scene scene;

    public static void main(String[] args) throws Exception {
        launch(args);
    }

    @Override
    public void start(Stage stage) throws IOException {
        scene = new Scene(loadFXML("mainScene"));
        stage.setScene(scene);
        stage.show();
    }
    private static Parent loadFXML(String fileName) throws IOException {
        FXMLLoader loader = new FXMLLoader(App.class.getResource(fileName+".fxml"));
        return loader.load();
    }
    static void setRoot(String fileName) {
        try {
            trySetRoot(fileName);
        }catch(IOException e) {
            System.err.println("Hiba! Az FXML betöltése sikertelen!");
            System.err.println(e.getMessage());
        }
    }
    static void trySetRoot(String fileName) throws IOException {
        scene.setRoot(loadFXML(fileName));
    }
}