Removing items in a collection based on listbox string - vb.net

Question

Having issues when clicking the remove button. If more of my code is needed, let me know. I get this error on the line AddressList.Remove(selectedName):
System.ArgumentException: 'Argument 'Key' is not a valid value.
I've tried many variations but can't figure out why this doesn't work. I think it has something to do with how the strings are concatenated in the listbox. I need to be able to remove entries from the collection and the listbox. Any help would be greatly appreciated.
Module EmailCollection
Public AddressList As New Collection
Public Sub AddRecord(ByVal a As cAddress)
Try
AddressList.Add(a)
Catch ex As Exception
MessageBox.Show("Error: inputs must be characters valid in string format")
End Try
End Sub
End Module
public class form1
Private Sub btnAdd_Click(sender As Object, e As EventArgs) Handles btnAdd.Click
Dim frmAdd As New AddNewName
frmAdd.ShowDialog()
UpdateListBox()
End Sub
Private Sub UpdateListBox()
lstAddress.Items.Clear()
Dim a As cAddress
For Each a In AddressList
lstAddress.Items.Add(String.Concat(a.strName, a.strEmail, a.strPhone, a.strComment))
Next
If lstAddress.Items.Count > 0 Then
lstAddress.SelectedIndex = 0
End If
End Sub
Private Sub btnRemove_Click(sender As Object, e As EventArgs) Handles btnRemove.Click
Dim selectedName As String
Try
' Get the selected value.
selectedName = lstAddress.SelectedItem.ToString()
' Remove the selected name from the list box and the collection.
If MessageBox.Show("Are you sure?",
"Confirm Deletion",
MessageBoxButtons.YesNo) = Windows.Forms.DialogResult.Yes Then
lstAddress.Items.Remove(selectedName)
AddressList.Remove(selectedName)
End If
Catch ex As NullReferenceException
MessageBox.Show("Select an item to remove.", "Selection Needed")
End Try
End Sub
end class

Answer 1

In your Module I changed AddressList from the old VB6 Collection type to the .net List(Of T). The T stands for Type.
Module EmailCollection
Public AddressList As New List(Of cAddress)
Public Sub AddRecord(ByVal a As cAddress)
AddressList.Add(a)
End Sub
End Module
I guessed that your cAddress class looks something like this. I added a custom .ToString method so the list box will display the data you wish but the item, itself, will be a cAddress object.
Public Class cAddress
Public Property strName As String
Public Property strEmail As String
Public Property strPhone As String
Public Property strComment As String
Public Overrides Function ToString() As String
Return $"{strName}, {strEmail}, {strPhone}, {strComment}"
End Function
End Class
In the Form...
Instead of adding a string to the list box I added the cAddress object. The list box calls .ToString on the object to get the display value.
Private Sub UpdateListBox()
ListBox1.Items.Clear()
For Each a As cAddress In AddressList
ListBox1.Items.Add(a)
Next
If ListBox1.Items.Count > 0 Then
ListBox1.SelectedIndex = 0
End If
End Sub
In the remove button I cast the selected item to its underlying type, cAddress. This is the item removed from the AddressList. Then simply remove the selected item from the list box.
Private Sub btnRemove_Click(sender As Object, e As EventArgs) Handles btnRemove.Click
If MessageBox.Show("Are you sure?",
"Confirm Deletion",
MessageBoxButtons.YesNo) = Windows.Forms.DialogResult.Yes Then
AddressList.Remove(DirectCast(ListBox1.SelectedItem, cAddress))
ListBox1.Items.Remove(ListBox1.SelectedItem)
End If
End Sub
I changed the name of the list box to ListBox1 to match my test project.

Answer 2

Here is something to try, use a BindingSource for setting up the ListBox. In the class override ToString to what is to be shown in the ListBox rather than what you are doing now without a DataSource.
My version of your class has name and property name changes.
Public Class Address
Public Property Name() As String
Public Property Email() As String
Public Property Phone() As String
Public Property Comment() As String
Public Overrides Function ToString() As String
Return $"{Name} {Email} {Phone} {Comment}"
End Function
End Class
Mocked data is used to populate the ListBox
Public Class Form1
Private ReadOnly _bsAddresses As New BindingSource
Private Sub UpdateListBox()
Dim AddressList = New List(Of Address) From
{
New Address() With {
.Name = "John",
.Email = "john#gmail.com",
.Phone = "555-444-3456",
.Comment = "AAA"},
New Address() With {
.Name = "Mary",
.Email = "mary#gmail.com",
.Phone = "888-333-2222",
.Comment = "BBB"},
New Address() With {
.Name = "Bob",
.Email = "bob#gmail.com",
.Phone = "111-555-9999",
.Comment = "CCC"}
}
_bsAddresses.DataSource = AddressList
lstAddress.DataSource = _bsAddresses
lstAddress.SelectedIndex = 0
End Sub
Private Sub Form1_Shown(sender As Object, e As EventArgs) _
Handles Me.Shown
UpdateListBox()
End Sub
Private Sub RemoveButton_Click(sender As Object, e As EventArgs) _
Handles RemoveButton.Click
If lstAddress.Items.Count > 0 AndAlso lstAddress.SelectedItem IsNot Nothing Then
Dim address = CType(_bsAddresses.Current, Address)
If My.Dialogs.Question($"Remove {address.Name}") Then
_bsAddresses.RemoveCurrent()
RemoveButton.Enabled = _bsAddresses.Count > 0
End If
End If
End Sub
End Class
Code module for asking a question
Namespace My
<ComponentModel.EditorBrowsable(ComponentModel.EditorBrowsableState.Never)>
Partial Friend Class _Dialogs
Public Function Question(text As String) As Boolean
Return (MessageBox.Show(
text,
My.Application.Info.Title,
MessageBoxButtons.YesNo,
MessageBoxIcon.Question,
MessageBoxDefaultButton.Button2) = MsgBoxResult.Yes)
End Function
End Class
<HideModuleName()>
Friend Module WinFormsDialogs
Private instance As New ThreadSafeObjectProvider(Of _Dialogs)
ReadOnly Property Dialogs() As _Dialogs
Get
Return instance.GetInstance()
End Get
End Property
End Module
End Namespace

Answer 3

Karen's post seems quite comprehensive. My response is an attempt to focus on your direct question.
I don't see all of the type definitions shown in your code, but in answer to your question, which I believe is "Why am I getting System.ArgumentException: 'Argument 'Key' is not a valid value":
In the offending line of code:
AddressList.Remove(selectedName)
AddressList is a collection. To use .Remove, you must pass in an object of the AddressList collection to remove it. You are passing a simple string, and that is not an AddressList object. You need to create an object based on your string selectedName to pass into .Remove and that line should work. The rest of what you are doing seems more complex.