Property is null just the first time

07-21-2009 1:57 PM |

How I test if the property is empty or null If  the first time I used the property it is always empty or null

    Public Sub New()
        InitializeComponent()

        objnumero.NOME = ""

        gridvalida.DataContext = objnumero
    End Sub

        Private privateNOME As String
        Public Property NOME() As String
            Get
                Return privateNOME
            End Get
            Set(ByVal value As String)
                If String.IsNullOrEmpty(value) Then
                    Throw New Exception("Obrigatório")
                End If
                privateNOME = value
                NotifyPropertyChanged("NOME")
            End Set
        End Property