Polymorphism/Serialization BinaryFormatter(C#)

using System;
using System.Collections.Generic;
using System.Text;
using System.Runtime.Serialization;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;

    namespace Polymorphism
    {
        class Program
        {
            static int Main(string[] args)
            {
                // Create some objects
                List<DrawingObject> dObj = new List<DrawingObject>();

                dObj.Add(new Line(100, 100));
                dObj.Add(new Circle(50,10,10));
                dObj.Add(new Square(10,10,20,20));
                dObj.Add(new DrawingObject());

                foreach (DrawingObject drawObj in dObj)
                {
                    switch (drawObj.GetType().Name)
                    {
                        case "Line":
                            Console.WriteLine (string.Format("I'm a {0}", drawObj.Draw()) );
                            Line line = (Line)drawObj;
                            break;
                        case "Circle":
                            Console.WriteLine (string.Format("I'm a {0}", drawObj.Draw()) );
                            Circle circle = (Circle)drawObj;
                            break;
                        case "Square":
                            Console.WriteLine (string.Format("I'm a {0}", drawObj.Draw()) );
                            Square square = (Square)drawObj;
                            break;
                        default:
                            Console.WriteLine (string.Format("I'm just a {0}", drawObj.Draw()) );
                            break;
                    }
                    drawObj.Draw();
                }

                // Serialize
                Serialize(dObj);

                List<DrawingObject> deserializedList = new List<DrawingObject>();
                // deserialize to a generic list
                deserializedList = Deserialize<List<DrawingObject>>();

                foreach (DrawingObject DrawingObject in deserializedList)
                {
                    switch (DrawingObject.GetType().Name)
                    {
                        case "Line":
                            Console.WriteLine (string.Format("I'm a {0}", DrawingObject.Draw()) );
                            Line line = (Line)DrawingObject;
                            break;
                        case "Circle":
                            Console.WriteLine (string.Format("I'm a {0}", DrawingObject.Draw()) );
                            Circle circle = (Circle)DrawingObject;
                            break;
                        case "Square":
                            Console.WriteLine (string.Format("I'm a {0}", DrawingObject.Draw()) );
                            Square square = (Square)DrawingObject;
                            break;
                        default:
                            Console.WriteLine (string.Format("I'm just a {0}", DrawingObject.Draw()) );
                            break;
                    }
                }

                return 0;
            }

            public static void Serialize<T>(T data)
            {
                try // try to serialize the collection to a file
                {
                    using (Stream  stream = File.Open("data.bin", FileMode.Create))
                    {
                        // create BinaryFormatter
                        BinaryFormatter bin = new BinaryFormatter();
                        // serialize the collection (EmployeeList1) to file (stream)
                        bin.Serialize(stream, data);
                    }
                }
                catch (IOException)
                {
                }
            }

            public static T Deserialize<T>() where T : new()
            {
                // Create an instance of T
                T ReturnListOfT = CreateInstance<T>();

                // Try to Deserialize from file stream
                try
                {
                    using (Stream stream = File.Open("data.bin", FileMode.Open))
                    {
                        // create BinaryFormatter
                        BinaryFormatter bin = new BinaryFormatter();
                        // deserialize the collection (Employee) from file (stream)
                        ReturnListOfT = (T)bin.Deserialize(stream);
                    }
                }
                catch (IOException)
                {
                }

                return (T)ReturnListOfT;
            }

            // function to create instance of T
            public static T CreateInstance<T>() where T : new()
            {
                return (T)Activator.CreateInstance(typeof(T));
            }
        }

        [KnownType(typeof(Line))]
        [KnownType(typeof(Circle))]
        [KnownType(typeof(Square))]
        [Serializable()]
        class DrawingObject
        {
            public virtual string Draw()
            {
                return "generic drawing object.";
            }
        }

        [Serializable()]
        class Square : DrawingObject
        {
            public override string Draw()
            {
                return "Square.";
            }

            public Square()
            {
            }

            public Square(int x1, int y1, int x2, int y2)
            {
                X1 = x1;
                Y1 = y1;
                X2 = x2;
                Y2 = y2;
            }

            public int X1 { get; set; }
            public int Y1 { get; set; }

            public int X2 { get; set; }
            public int Y2 { get; set; }
        }

        [Serializable()]
        class Line : DrawingObject
        {
            public override string Draw()
            {
                return "Line.";
            }

            public Line()
            {
            }

            public Line(int x, int y)
            {
                this.X = x;
                this.Y = y;
            }

            public int X { get; set; }
            public int Y { get; set; }
        }

        [Serializable()]
        class Circle : DrawingObject
        {
            public override string Draw()
            {
                return "Circle.";
            }

            public Circle()
            {
            }

            public Circle(int radius, int x, int y)
            {
                this.Radius = radius;
                this.X = x;
                this.Y = y;
            }

            public int Radius { get; set; }
            public int X { get; set; }
            public int Y { get; set; }
        }
    }