Source:
<code>public void start(Stage stage) { try { FXMLLoader loader = new FXMLLoader(getClass().getResource("/views/window.fxml")); Parent root = (Parent) loader.load(); final WindowController controller = (WindowController) loader.getController(); App.controller = controller; Scene scene = new Scene(root, 1200, 800); stage.setTitle("Demo Sprint 3"); stage.setScene(scene); stage.show(); try { LibraryLoader libraryLoader = new LibraryLoader("library.xml"); library = libraryLoader.load(); if (library.size() < 1) { empty = true; } } catch (IOException | NullPointerException e) { library = new Library(); empty = true; } scene.getWindow().setOnHidden(new EventHandler<WindowEvent>() { @Override public void handle(WindowEvent arg0) { if (library != null) { XmlExport exporter = new XmlExport("library.xml", library); exporter.export(); <START> System.out.println(library.size()); <END> } System.exit(0); } }); if (empty) { String directory = ""; DirectoryChooser directoryChooser = new DirectoryChooser(); File selectedDirectory = directoryChooser.showDialog(null); if (selectedDirectory == null) { System.out.println("No directory selected."); System.exit(-1); } else { directory = selectedDirectory.getAbsolutePath(); } FolderLoader folderLoader = new FolderLoader(directory); String playlistname = FileName.getName(directory); Playlist playlist = folderLoader.load(); PlaylistSorter sorter = new MaximumFlowPlaylistSorter(); Playlist mixablePlaylist = sorter.sort(playlist); controller.setEverything(mixablePlaylist, playlistname); } else { controller.setLibrary(library); } } catch (Exception e) { log.fatal(e.getMessage(), e); System.exit(-1); } }</code><technical_language>please remove system.out replace a logger</technical_language>

Target:
public void start(Stage stage) { try { FXMLLoader loader = new FXMLLoader(getClass().getResource("/views/window.fxml")); Parent root = (Parent) loader.load(); final WindowController controller = (WindowController) loader.getController(); App.controller = controller; Scene scene = new Scene(root, 1200, 800); stage.setTitle("Demo Sprint 3"); stage.setScene(scene); stage.show(); try { LibraryLoader libraryLoader = new LibraryLoader("library.xml"); library = libraryLoader.load(); if (library.size() < 1) { empty = true; } } catch (IOException | NullPointerException e) { library = new Library(); empty = true; } scene.getWindow().setOnHidden(new EventHandler<WindowEvent>() { @Override public void handle(WindowEvent arg0) { if (library != null) { XmlExport exporter = new XmlExport("library.xml", library); exporter.export(); } System.exit(0); } }); if (empty) { String directory = ""; DirectoryChooser directoryChooser = new DirectoryChooser(); File selectedDirectory = directoryChooser.showDialog(null); if (selectedDirectory == null) { log.warn("No directory selected."); System.exit(-1); } else { directory = selectedDirectory.getAbsolutePath(); } FolderLoader folderLoader = new FolderLoader(directory); String playlistname = FileName.getName(directory); Playlist playlist = folderLoader.load(); PlaylistSorter sorter = new MaximumFlowPlaylistSorter(); Playlist mixablePlaylist = sorter.sort(playlist); controller.setEverything(mixablePlaylist, playlistname); } else { controller.setLibrary(library); } } catch (Exception e) { log.fatal(e.getMessage(), e); System.exit(-1); } }