access to new dynamically controls in vb.net - vb.net

Question

First of all excuse me for my poor grammar and vocabulary :)
please see this source and run it:
Public Class Form1
Public pointX As Integer
Public pointY As Integer = 32
Public dynamicText As TextBox
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
pointX = 330
For i = 1 To 4
dynamicText = New Windows.Forms.TextBox
dynamicText.Name = "T" + Trim(Str(i))
dynamicText.Text = ""
dynamicText.Location = New Point(pointX, pointY)
dynamicText.Size = New Size(100, 20)
Me.Controls.Add(dynamicText)
pointX = pointX - 106
Next
End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
pointX = 330
pointY = pointY + 26
For i = 1 To 4
dynamicText = New Windows.Forms.TextBox
dynamicText.Name = "T" + Trim(Str(i))
dynamicText.Text = ""
dynamicText.Location = New Point(pointX, pointY)
dynamicText.Size = New Size(100, 20)
Me.Controls.Add(dynamicText)
pointX = pointX - 106
AddHandler dynamicText.Click, AddressOf printHello1
Next
End Sub
Private Sub printHello1(ByVal sender As System.Object, ByVal e As System.EventArgs)
MsgBox(dynamicText.Name)
If dynamicText.Name = "T1" Then MsgBox("Oh! this is T1")
End Sub
End Class
why If never is not true?!
why MsgBox(dynamicText.Name) always return T4?!
i want all controlls to be access by name or array of names.
please help me thank you. :)

Answer 1

The global variable dynamicText takes the value of the last TextBox added in the loop inside the Button1_Click event. This happens to be the control named T4. You don't really need a global variable in this case. You can cast the sender parameter to a TextBox instance because the sender parameter is the control that has raised the event.
Private Sub printHello1(ByVal sender As System.Object, ByVal e As System.EventArgs)
Dim txt = CType(sender, "TextBox")
if txt IsNot Nothing then
MsgBox(txt.Name)
If txt.Name = "T1" Then MsgBox("Oh! this is T1")
End If
End Sub
You also don't need to recreate the controls again in the button click event. The action executed in the form load event is enough (You could add the AddHandler there). Global variables are dangerous, avoid them when possible.

Answer 2

See if this is acceptable. Place a panel at the bottom of your form, set Dock to Bottom, add a single button to the panel and a TextBox. Place a FlowLayoutPanel onto the form, Dock = Fill, AutoScroll = True.
The code below creates the amount of TextBox controls as inputted into TextBox. Each newly created TextBox a click event is added with simple logic.
Form code
Public Class Form1
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim count As Integer = 0
If Integer.TryParse(TextBox1.Text, count) Then
Dim demo = New TextBoxCreate(FlowLayoutPanel1, "Demos", count)
demo.CreateTextBoxes()
End If
End Sub
End Class
Class code (add a new class to the project, name it TextBoxCreate.vb)
Public Class TextBoxCreate
Public Property TextBoxes As TextBox()
Public Property TextBoxBaseName As String
Public Property TextBoxCount As Integer
Public Property ParentControl As Control
Public Sub New(
ByVal ParentControl As Control,
ByVal BaseName As String,
ByVal Count As Integer)
Me.ParentControl = ParentControl
Me.TextBoxBaseName = BaseName
Me.TextBoxCount = Count
End Sub
Public Sub CreateTextBoxes()
Dim Base As Integer = 10
TextBoxes = Enumerable.Range(0, TextBoxCount).Select(
Function(Indexer)
Dim b As New TextBox With
{
.Name = String.Concat(TextBoxBaseName, Indexer + 1),
.Text = (Indexer + 1).ToString,
.Width = 150,
.Location = New Point(25, Base),
.Parent = Me.ParentControl,
.Visible = True
}
AddHandler b.Click, Sub(sender As Object, e As EventArgs)
Dim tb As TextBox = CType(sender, TextBox)
If tb.Name = TextBoxBaseName & "1" Then
tb.Text = "Got it"
Else
MessageBox.Show(tb.Name)
End If
End Sub
Me.ParentControl.Controls.Add(b)
Base += 30
Return b
End Function).ToArray
End Sub
End Class