IO

private void createLib() {
        File file = new File("books.txt");
        FileWriter fileWriter = null;
        try {
            fileWriter = new FileWriter(file, false);
            size = 5;
            fileWriter.write(String.valueOf(size));
            fileWriter.write('\n');
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        String book = new String("1###J. R. R. Tolkien###The Fellowship of the Ring###423###1954###2000###11###01");
        try {
            fileWriter.write(book);
            fileWriter.write('\n');
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        book = new String("2##J. R. R. Tolkien###The Two Towers###352###1954###2000###11###19");
        try {
            fileWriter.write(book);
            fileWriter.write('\n');
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        book = new String("3###J. R. R. Tolkien###The Return of the King###416###1955###2000###12###26");
        try {
            fileWriter.write(book);
            fileWriter.write('\n');
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        book = new String("4###Ray Bradbury###Fahrenheit 451###158###1953###2000###10###19");
        try {
            fileWriter.write(book);
            fileWriter.write('\n');
            fileWriter.flush();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        book = new String("5###Agatha Christie###And Then There Were None###272###1939###2000###10###19");
        try {
            fileWriter.write(book);
            fileWriter.write('\n');
            fileWriter.flush();
        } catch (IOException ex) {
            ex.printStackTrace();
        }

    }

    public void writeToFile(List<Book> books) {
        try {
            File file = new File("books.txt");
            FileWriter fileWriter = new FileWriter(file, false);
            fileWriter.write(String.valueOf(size));
            fileWriter.write('\n');
            for (Book book : books) {
                String bookLine = new String(book.getId() + "###" +
                        book.getAuthor() + "###" +
                        book.getTitle() + "###" +
                        book.getPageNum() + "###" +
                        book.getPublishingYear() + "###" +
                        book.getAddedYear() + "###" +
                        book.getAddedMonth() + "###" +
                        book.getAddedDay());
                fileWriter.write(bookLine);
                fileWriter.write('\n');
            }
            fileWriter.flush();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    public List<Book> readFromFile() {
        List<Book> books = new ArrayList<>();
        try {
            File file = new File("books.txt");
            FileReader fileReader = new FileReader(file);
            BufferedReader bufferedReader = new BufferedReader(fileReader);
            String bookLine = bufferedReader.readLine();
            size = Integer.valueOf(bookLine);
            System.out.println("Books in library: " + size);
            bookLine = bufferedReader.readLine();
            while (bookLine != null) {
                StringTokenizer stringTokenizer = new StringTokenizer(bookLine, "###");
                books.add(new Book(Integer.valueOf(stringTokenizer.nextToken()),
                        stringTokenizer.nextToken(), stringTokenizer.nextToken(),
                        Integer.valueOf(stringTokenizer.nextToken()),
                        Integer.valueOf(stringTokenizer.nextToken()),
                        Integer.valueOf(stringTokenizer.nextToken()),
                        Integer.valueOf(stringTokenizer.nextToken()),
                        Integer.valueOf(stringTokenizer.nextToken())));
                bookLine = bufferedReader.readLine();
            }
        } catch (IOException ex) {
            ex.printStackTrace();
        }
        return books;
    }
}