Invalid cast exception
- by user127147
I have a simple application to store address details and edit them. I have been away from VB for a few years now and need to refreash my knowledge while working to a tight deadline. I have a general Sub responsible for displaying a form where user can add contact details (by pressing button add) and edit them (by pressing button edit). This sub is stored in a class Contact. The way it is supposed to work is that there is a list with all the contacts and when new contact is added a new entry is displayed. If user wants to edit given entry he or she selects it and presses edit button
Public Sub Display()
Dim C As New Contact
C.Cont = InputBox("Enter a title for this contact.")
C.Fname = frmAddCont.txtFName.Text
C.Surname = frmAddCont.txtSName.Text
C.Address = frmAddCont.txtAddress.Text
frmStart.lstContact.Items.Add(C.Cont.ToString)
End Sub
I call it from the form responsible for adding new contacts by
Dim C As New Contact
C.Display()
and it works just fine. However when I try to do something similar using the edit button I get errors - "Unable to cast object of type 'System.String' to type 'AddressBook.Contact'."
Dim C As Contact
If lstContact.SelectedItem IsNot Nothing Then
C = lstContact.SelectedItem()
C.Display()
End If
I think it may be something simple however I wasn't able to fix it and given short time I have I decided to ask for help here.
I have updated my class with advice from other members and here is the final version (there are some problems however). When I click on the edit button it displays only the input box for the title of the contact and actually adds another entry in the list with previous data for first name, second name etc.
Public Class Contact
Public Contact As String
Public Fname As String
Public Surname As String
Public Address As String
Private myCont As String
Public Property Cont()
Get
Return myCont
End Get
Set(ByVal value)
myCont = Value
End Set
End Property
Public Overrides Function ToString() As String
Return Me.Cont
End Function
Sub NewContact()
FName = frmAddCont.txtFName.ToString
frmStart.lstContact.Items.Add(FName)
frmAddCont.Hide()
End Sub
Public Sub Display()
Dim C As New Contact
C.Cont = InputBox("Enter a title for this contact.")
C.Fname = frmAddCont.txtFName.Text
C.Surname = frmAddCont.txtSName.Text
C.Address = frmAddCont.txtAddress.Text
'frmStart.lstContact.Items.Add(C.Cont.ToString)
frmStart.lstContact.Items.Add(C)
End Sub
End Class
