public static void main(String[] args) {
        try {
            JAXBContext context = JAXBContext.newInstance(BookList.class);
            Unmarshaller um = context.createUnmarshaller();
            FileReader file = new FileReader("books.xml");
            BookList books = (BookList) um.unmarshal(file);
            file.close();
            BookManager bm = new BookManager(books.getBooks());
            List<Book> javaBooks = bm.searchByTitle("Java");

            Book lab_book = new Book("lab_book", "Laboratorium: Java i XML", "Dawid Gliński", "12345678", 2014, "ZUT", 1000);
            javaBooks.add(lab_book);
            Marshaller marshaller = context.createMarshaller();
            books.setList(javaBooks);
            marshaller.marshal(books, new File("lab3.xml"));
        } catch (JAXBException ex) {
            ex.printStackTrace();
        } catch (FileNotFoundException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
        }

    }