Polymorphism/Serialization BinaryFormatter(VB.NET)

Imports System.IO
Imports System.Collections
Imports System.Runtime.Serialization.Formatters.Binary
Imports System.Runtime.Serialization

Module Module1

    Sub Main()
        'Create some objects
        Dim dObj As New List(Of 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())

        For Each drawObj As DrawingObject In dObj

            Select Case drawObj.GetType().Name
                Case "Line"
                    Console.WriteLine(String.Format("I'm a {0}", drawObj.Draw()))
                    Dim line As Line = DirectCast(drawObj, Line)
                Case "Circle"
                    Console.WriteLine(String.Format("I'm a {0}", drawObj.Draw()))
                    Dim circle As Circle = DirectCast(drawObj, Circle)
                Case "Square"
                    Dim square As Square = DirectCast(drawObj, Square)
                    Console.WriteLine(String.Format("I'm a {0}", drawObj.Draw()))
                Case Else
                    Console.WriteLine(String.Format("I'm just a {0}", drawObj.Draw()))
            End Select
            drawObj.Draw()
        Next

        ' Serialize
        Serialize(dObj)

        Dim deserializedList = New List(Of DrawingObject)()
        ' deserialize to a generic list
        deserializedList = Deserialize(Of List(Of DrawingObject))()

        For Each DrawingObject As DrawingObject In deserializedList

            Select Case DrawingObject.GetType().Name
                Case "Line"
                    Console.WriteLine(String.Format("I'm a {0}", DrawingObject.Draw()))
                    Dim line As Line = DirectCast(DrawingObject, Line)
                Case "Circle"
                    Console.WriteLine(String.Format("I'm a {0}", DrawingObject.Draw()))
                    Dim circle As Circle = DirectCast(DrawingObject, Circle)
                Case "Square"
                    Dim square As Square = DirectCast(DrawingObject, Square)
                    Console.WriteLine(String.Format("I'm a {0}", DrawingObject.Draw()))
                Case Else
                    Console.WriteLine(String.Format("I'm just a {0}", DrawingObject.Draw()))
            End Select
        Next

    End Sub

    Public Sub Serialize(Of T)(data As T)
        Try
            Using stream As New FileStream("data.bin", FileMode.Create)

                ' create BinaryFormatter
                Dim bin = New Formatters.Binary.BinaryFormatter()
                ' serialize the collection (EmployeeList1) to file (stream)
                bin.Serialize(stream, data)

            End Using
        Catch ex As Exception
        End Try
    End Sub

    Private Function Deserialize(Of T)() As T
        ' Create an instance of T
        Dim ReturnListOfT = CreateInstance(Of T)()

        Try
            Using stream As New FileStream("data.bin", FileMode.Open)

                ' create BinaryFormatter
                Dim bin = New Formatters.Binary.BinaryFormatter()
                ' deserialize the collection (Employee) from file (stream)
                ReturnListOfT = DirectCast(bin.Deserialize(stream), T)

            End Using
        Catch ex As Exception
        End Try

        Return DirectCast(ReturnListOfT, T)
    End Function

    ' function to create instance of T
    Private Function CreateInstance(Of T)() As T
        Return DirectCast(Activator.CreateInstance(GetType(T)), T)
    End Function

End Module

<KnownType(GetType(Line))>
<KnownType(GetType(Circle))>
<KnownType(GetType(Square))>
<Serializable()>
Public Class DrawingObject

    Public Sub New()

    End Sub

    Public Overridable Function Draw() As String
        Return "generic drawing object."
    End Function
End Class

<Serializable()>
Public Class Square
    Inherits DrawingObject

    Public Overrides Function Draw() As String
        Return "Circle."
    End Function

    Public Sub New()
    End Sub

    Public Sub New(x1 As Integer, y1 As Integer, x2 As Integer, y2 As Integer)
        Me.X1 = x1
        Me.Y1 = y1
        Me.X2 = x2
        Me.Y2 = y2
    End Sub

    Public Property X1 As Integer
    Public Property Y1 As Integer
    Public Property X2 As Integer
    Public Property Y2 As Integer
End Class

<Serializable()>
Public Class Line
    Inherits DrawingObject

    Public Overrides Function Draw() As String
        Return "Line."
    End Function

    Public Sub New()
    End Sub

    Public Sub New(x As Integer, y As Integer)

        Me.X = x
        Me.Y = y
    End Sub

    Public Property X As Integer
    Public Property Y As Integer
End Class

<Serializable()>
Public Class Circle
    Inherits DrawingObject

    Public Overrides Function Draw() As String
        Return "Circle."
    End Function

    Public Sub New()
    End Sub

    Public Sub New(radius As Integer, x As Integer, y As Integer)
        Me.Radius = radius
        Me.X = x
        Me.Y = y
    End Sub

    Public Property Radius As Integer
    Public Property X As Integer
    Public Property Y As Integer

End Class