VB.NET System.NullReferenceException

I was wondering how i can handle / catch any property in a Data Class which is not initialized ?
I know i can set it to "" when i create a new instance but i still would like to handle the possible exception.

In my case i loop thru the data values in my data Class and when i get to an item that is not initialized i get
the System.NullReferenceException.

Below is the code i use so far

   Dim myQueryString As String = ""

        Dim _type As Type = myData.GetType()
        Dim properties() As PropertyInfo = _type.GetProperties()
        For Each _property In properties

            If _property.GetValue(myData, Nothing).ToString IsNot Nothing Then
                If _property.GetValue(myData, Nothing).ToString <> "" Then

                    myQueryString += "" & _property.Name & ": '" & _property.GetValue(myData, Nothing).ToString & "' ,"

                End If
            End If
        Next

Select allOpen in new window