<Serializable()> _
Public Class Spion
    Implements IDisposable
 
    <Serializable()> _
    Public Class SpionItem
 
        Public ReadOnly ComboItem As String
        Public ReadOnly DatumZeit As DateTime
        'weitere Info-Properties z.B. Benutzer 
 
        Public Sub New(ComboText As String, dt As DateTime)
            ComboItem = ComboText
            DatumZeit = dt
        End Sub
    End Class
 
    Private SpionDatei As String
 
    Private ReadOnly SpionItemList As New List(Of SpionItem)
 
    <NonSerialized()> _
    Dim fmt As New System.Runtime.Serialization.Formatters. _
        Binary.BinaryFormatter()
 
    Public Sub New(SpionDateiPfad As String)
       If IO.File.Exists(SpionDateiPfad) Then
          Using fs As New IO.FileStream(SpionDateiPfad, _
             IO.FileMode.Open, IO.FileAccess.Read, IO.FileShare.None)
             Dim cs As Spion = DirectCast(fmt.Deserialize(fs), Spion)
             Me.SpionItemList = cs.SpionItemList
          End Using
       End If
       SpionDatei = SpionDateiPfad
    End Sub
 
 
    Public Sub addItem(Combotext As String, dt As DateTime)
        SpionItemList.Add(New SpionItem(Combotext, dt))
    End Sub
 
 
    Public ReadOnly Property GetList As DataTable
        Get
            Dim dt As New DataTable
            dt.Columns.Add("ComboItem") : dt.Columns.Add("DatumZeit")
            With SpionItemList
                For i As Integer = 0 To .Count - 1
                    dt.Rows.Add(.Item(i).ComboItem, .Item(i).DatumZeit)
                Next i
            End With
 
            Return dt
        End Get
    End Property
 
 
    Public Sub Serialize()
        IO.File.Delete(SpionDatei)
        Try
            Using fs As New IO.FileStream(SpionDatei, _
                IO.FileMode.Create, IO.FileAccess.Write, IO.FileShare.None)
                fmt.Serialize(fs, Me)
            End Using
        Catch ex As Exception
            Stop
        End Try
    End Sub
 
    Private disposedValue As Boolean
    Protected Overridable Sub Dispose(disposing As Boolean)
        If Not Me.disposedValue Then
            If disposing Then
                Serialize()
            End If
        End If
        Me.disposedValue = True
    End Sub
 
    Public Sub Dispose() Implements IDisposable.Dispose
        Dispose(True)
        GC.SuppressFinalize(Me)
    End Sub
End Class

Public Class ComboBoxSpion
    Inherits ComboBox
 
    Dim sp As New Spion("C:\Daten\ComboboxSpionage.ser")
 
    Protected Overrides Sub OnSelectedIndexChanged(e As System.EventArgs)
        MyBase.OnSelectedIndexChanged(e)
        sp.addItem(DirectCast(Me.Items(Me.SelectedIndex), String), Now)
    End Sub
 
    Public ReadOnly Property GetSpionItems() As DataTable
        Get
            Return sp.GetList
        End Get
    End Property
 
    Private Sub ComboBoxSpion_Disposed(sender As Object, _
        e As System.EventArgs) Handles Me.Disposed
        sp.Serialize()
    End Sub
End Class

Public Class frmComboBoxSpion
 
    Dim cbo As New ComboBoxSpion With _
        {.Parent = Me, .Width = 200, .Height = 50}
    Dim dt As DataTable
    Dim bs As New BindingSource
    Dim dgv As New DataGridView With _
        {.Parent = Me, .Width = 200, .Height = 200, _
         .Top = 110, .DataSource = bs}
    Dim WithEvents btn As New Button With _
        {.Parent = Me, .Width = 200, .Top = 80, _
         .Text = "Items zeigen"}
 
    Private Sub frmComboBoxSpion_Load(sender As System.Object, _
        e As System.EventArgs) Handles MyBase.Load
        cbo.Items.AddRange({"Projekt Müller", "Angebot Meier", _
                            "Rechnung Schröder", "Projekt Buchs"})
    End Sub
 
 
    Private Sub btn_Click(sender As Object, _
        e As System.EventArgs) Handles btn.Click
 
        bs.DataSource = cbo.GetSpionItems
    End Sub
End Class