javafx DragDropped file

  public class EffectTest extends Application {
@Override
    public void start(Stage primaryStage) {
        Group root = new Group();
        Scene scene = new Scene(root, , );
        scene.setOnDragOver((DragEvent event) -> {
            Dragboard db = event.getDragboard();
            if (db.hasFiles()) {
                event.acceptTransferModes(TransferMode.COPY);
            } else {
                event.consume();
            }
        });

        // Dropping over surface
        scene.setOnDragDropped((DragEvent event) -> {
            Dragboard db = event.getDragboard();
            boolean success = false;
            if (db.hasFiles()) {
                success = true;
                String filePath = null;
                for (File file:db.getFiles()) {
                    filePath = file.getAbsolutePath();
                    System.out.println(filePath);
                }
            }
            event.setDropCompleted(success);
            event.consume();
        });

        primaryStage.setScene(scene);
        primaryStage.show();
    }

}