<System.Serializable()>
Public Class cAdresse
 
    Public Name As String
    Public Vorname As String
    Public Ort As String
    Public StrasseNummer As String
End Class
 
 
<System.Serializable()>
Public Class cUser
    Public _name As String
    Private _Passwort As String
 
    Private _Adressen As New List(Of cAdresse)
 
 
    Public Sub New(Name As String, Passwort As String)
        _name = Name
        _Passwort = Passwort
    End Sub
 
 
    Public Function Passwort(ByVal pw As String) As Boolean
        Return pw = _Passwort
    End Function
 
 
    Public Sub Add_Adresse(addr As cAdresse)
        _Adressen.Add(addr)
    End Sub
 
 
    Public Sub Delete_Adresse(addr As cAdresse)
        Dim index As Integer = _Adressen.IndexOf(addr)
        If Not index = -1 Then
           _Adressen.RemoveAt(index)
        End If        
    End Sub
End Class
 
 
Public Class AdressenListe
 
    Dim bf As New _
    System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
 
    Private _users As New List(Of cUser)
    Private _user As cUser
 
    Public Sub Add_User(user As cUser)
        _users.Add(user)
    End Sub
 
    Public Function Anmeldung(name As String, passwort As String) As Boolean
 
        For Each user As cUser In _users
            If user._name = name Then
                If user.Passwort(passwort) Then
                    _user = user
                    Return True
                Else
                    _user = Nothing
                End If
            End If
        Next user
        Return False
    End Function
 
    Public Sub Add_Adresse(addr As cAdresse)
        _user.Add_Adresse(addr)
    End Sub
 
    Public Sub Speichern()
 
        Using fs As New IO.FileStream("C:\daten\addr.ser", _
            IO.FileMode.OpenOrCreate, IO.FileAccess.Write)
            bf.Serialize(fs, _users)
        End Using
    End Sub
 
    Public Sub Laden()
 
        Using fs As New IO.FileStream("C:\daten\addr.ser", _
            IO.FileMode.Open, IO.FileAccess.Read)
            _users = CType(bf.Deserialize(fs), List(Of cUser))
            _user = Nothing
        End Using
    End Sub
End Class