Get items and index of dynamic comboBox in VB.NET - vb.net

Question

I have created a list of eight dynamic comboBoxes through the function combox1Gen() and then i have loaded items to them from a text file of values through function loadComboboxItems(). On every respective comboBox's item selection i need to display the value and its index. what code should in put inside ComboTName_SelectedIndexChanged()?
One more issue is there. My comboBoxes with items get loaded very slowly in a hanging way. whats wrong with my code?
My code is below:
Public ComboBoxesTname As New List(Of ComboBox)
Dim i As Integer = 0
Do While i <= 7
Combo1Gen(i)
i = i + 1
Loop
loadComboboxItems()
Private Function Combo1Gen(ByVal n As Integer) As Boolean
Try
Dim newCombo As New ComboBox
With newCombo
.Name = "MyComboBox1" & n.ToString
.Left = 110
.Top = 120 + (52 * n) + 20
.Width = 180
.Height = 20
.Visible = True
End With
ComboBoxesTname.Add(newCombo)
GroupBox1.Controls.Add(newCombo)
GroupBox1.AutoSize = True
AddHandler newCombo.SelectedIndexChanged, AddressOf ComboTName_SelectedIndexChanged
Return True
Catch ex As Exception
MessageBox.Show(ex.ToString)
Return False
End Try
End Function
Private Function loadComboboxItems() As Boolean
Try
Dim listT As New List(Of String)()
listT = ReadVars.readVars(GetFolderPath.GetFolderPath("\vars\"), "items.txt")
For i = 0 To ComboBoxesTname.Count - 1
ComboBoxesTname(i).Items.AddRange(listT.ToArray)
Next
Return True
Catch ex As Exception
Debug.WriteLine(ex.ToString)
MessageBox.Show("Error: " & Err.ToString)
Return False
End Try
Return False
End Function
Private Sub ComboTName_SelectedIndexChanged()
End Sub

Answer 1

I am not sure exactly what you want to do in SelectIndexChanged but I showed how to get the values from the combo that was clicked.
See comments and explanations in line.
Public ComboBoxesTname As New List(Of ComboBox)
Private Sub LoadCombos()
For i = 0 To 7
Combo1Gen(i)
Next
loadComboboxItems()
End Sub
'Since you never use the return value I changed this to a Sub
Private Sub Combo1Gen(ByVal n As Integer)
Dim newCombo As New ComboBox
With newCombo
.Name = "MyComboBox1" & n.ToString
.Left = 110
.Top = 10 + (52 * n) + 20
.Width = 180
.Height = 20
.Visible = True
End With
ComboBoxesTname.Add(newCombo)
GroupBox1.Controls.Add(newCombo)
GroupBox1.AutoSize = True
AddHandler newCombo.SelectedIndexChanged, AddressOf ComboTName_SelectedIndexChanged
End Sub
'Since I don't have access to ReadVars I created an arbitrary array to test
Private listT As String() = {"Mathew", "Mark", "Luke", "John"}
'You should have readVars return an array of strings
'Create this once as a Form level variable so you don't have to read the file over and over
'Private listT As String() = ReadVars.readVars(GetFolderPath.GetFolderPath("\vars\"), "items.txt")
'Since you never use the return value I changed this to a Sub
Private Sub loadComboboxItems()
For i = 0 To ComboBoxesTname.Count - 1
ComboBoxesTname(i).Items.AddRange(listT)
Next
End Sub
'Added the appropriate parameters
Private Sub ComboTName_SelectedIndexChanged(sender As Object, e As EventArgs)
'Cast sender to a ComboBox so we can use the Properties of a ComboBox
Dim Combo = DirectCast(sender, ComboBox)
Dim Name = Combo.Name
Dim Item = Combo.SelectedItem
MessageBox.Show($"The selected item in {Name} is {Item}")
End Sub
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
LoadCombos()
End Sub
EDIT
In response to your question in comments. I added a Function and a few changes to ComboTName_SelectedIndexChanged
Private Sub ComboTName_SelectedIndexChanged(sender As Object, e As EventArgs)
'Cast sender to a ComboBox so we can use the Properties of a ComboBox
Dim Combo = DirectCast(sender, ComboBox)
Dim Name = Combo.Name
Dim N As Integer = GetValueOfN(Name)
Dim Item = Combo.SelectedItem
MessageBox.Show($"The selected item in {Name} is {Item} The number of the combo cox is {N}")
End Sub
Private Function GetValueOfN(ComboName As String) As Integer
Dim NumString = ComboName.Substring(ComboName.IndexOf("1") + 1)
Return CInt(NumString)
End Function