vb.net string lookup in listbox with output as different part of the string - vb.net

Question

Last Name Finder
what I'm trying to do is create a list of all peoples surnames where the 1st name = #name
although this isn't the exact purpose its easier to try and explain the actual content. i'm aware it may be easier to use a data source, but I want to try and avoid that where possible.
Form_Load
ListBox1.Items.Add("Dean Smith")
ListBox1.Items.Add("John Jones")
ListBox1.Items.Add("David Johnson")
ListBox1.Items.Add("Samantha Thompson")
ListBox1.Items.Add("Claire Frost")
ListBox1.Items.Add("John Brown")
and then some sort of string manipulation to do the following on button_click
if textbox1.text contains "John" then
listbox2.items.add(Jones)
listbox2.items.add(Brown)
else messagebox.show("No matches found")
end if
Thanks for any input.

Answer 1

What I've understood is that you are willing to use your textbox as a filter to the listbox. And this can be achieved by running the query to your db on every TextChanged().
So to give you some guidelines, you can proceed like this;
private Names As List(Of String)
Private Sub Form2_Load1(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
Names = New List(Of String)
With Names
.Add("Dean Smith")
.Add("John Jones")
.Add("John Brown")
End With
For Each Name As String In Names
ListBox1.Items.Add(Name)
Next
End sub
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
ListBox1.Items.Clear()
For Each s As String In Names
If s.Substring(0, TextBox1.Text.Length).ToLower = TextBox1.Text.ToLower Then
ListBox1.Items.Add(s)
End If
Next
End Sub
I hope this solution might help you achieve what you wanted. You can also apply direct filter to the List by using a delegate function, which will avoid you from looping again on TextChange().