JavaFX Quit button program

import javafx.application.Application;
import javafx.application.Platform;
import javafx.event.ActionEvent;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;

public class QuitButtonEx extends Application {

    @Override
    public void start(Stage stage) {

        initUI(stage);
    }

    private void initUI(Stage stage) {

        Button btn = new Button();
        btn.setText("Quit");
        btn.setOnAction((ActionEvent event) -> {
            Platform.exit();
        });

        HBox root = new HBox();
        root.setPadding(new Insets(25));
        root.getChildren().add(btn);

        Scene scene = new Scene(root, 280, 200);

        stage.setTitle("Quit button");
        stage.setScene(scene);
        stage.show();
    }

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