C# BinaryFormatter Serialize and Deserialize

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace WpfApp291
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            //BinaryFormatterSerializeDemo();
            BinaryFormatterDeserializeDemo();
        }

        private void BinaryFormatterDeserializeDemo()
        {
            if (File.Exists("bin.data"))
            {
                using (FileStream fs = new FileStream("bin.data", FileMode.OpenOrCreate, FileAccess.ReadWrite))
                {
                    BinaryFormatter binFormatter = new BinaryFormatter();
                    var bks = (List<Book>)binFormatter.Deserialize(fs);
                    fs.Close();
                }
            }
        }

        private void BinaryFormatterSerializeDemo()
        {
            List<Book> books = new List<Book>();
            for (int i = 0; i < 10000; i++)
            {
                books.Add(new Book()
                {
                    Id = i,
                    Name = $"Name_{i}",
                    Title = $"Title_{i}",
                    Topic = $"Topic_{i}"
                });
            } 
            using (FileStream fs = new FileStream("bin.data", FileMode.OpenOrCreate, FileAccess.ReadWrite))
            {
                BinaryFormatter binFormatter = new BinaryFormatter();
                binFormatter.Serialize(fs, books);
                fs.Close();
            }
        }
    }

    [Serializable]
    class Book
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string Title { get; set; }

        public string Topic { get; set; }
    }
}