How to address a dynamically added label-CodePudding

In a timer program I am building, I have multiple entrants added dynamically, this bit is easy. Where I am having trouble, I need to activate a stop watch to time the change over, this happens in one of the dynamically added labels, from the dynamically added button. So the code I have from my timer looks like this, when I run the click event I get this result

System.NullReferenceException: 'Object variable or With block variable not set.'

Public Class Form1
ReadOnly MyForm
Dim ss, tt, vv As Integer
Dim ss1, tt1, vv1, ww1 As Integer

'Dim NewLab1


Dim CarNum

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    Dim NewBut1 = New Button
    Dim NewBut2 = New Button
    Dim NewLab1 = New Label
    Dim NewLab2 = New Label
    Dim NewLab3 = New Label
    Timer3.Enabled = True





    ' NewBut1()

End Sub

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
    Label3.Text = Format(ss, "00:") & Format(tt, "00:") & Format(vv, "00")
    vv = vv   1
    If vv > 59 Then
        vv = 0
        tt = tt   1
    End If
    If tt = 2 Then
        vv = 0
        tt = 0
        Label3.Text = "00:00:00"
        Timer1.Enabled = False
        MessageBox.Show("time ended")
    End If
End Sub

Private Sub Timer3_Tick(sender As Object, e As EventArgs) Handles Timer3.Tick
    Label2.Text = Format(Now, "hh:mm:ss")
End Sub

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    CarNum = InputBox("Add Car Number", "Car Number")

    Dim NewBut1 = New Button
    Dim NewBut2 = New Button
    Dim NewLab1 = New Label
    Dim NewLab2 = New Label
    Dim NewLab3 = New Label


    With NewBut1
        .BackColor = Color.Red
        .ForeColor = Color.White
        .Text = "Car " & CarNum & " Pit IN"
        .Location = New Point(12, 200)
        .Height = 60
        .Width = 188
        .Font = New Font("Arial Rounded ", 16, FontStyle.Bold)
        AddHandler NewBut1.Click, AddressOf NewBut1_Click
    End With
    With NewBut2
        .BackColor = Color.Lime
        .ForeColor = Color.Black
        .Text = "Car " & CarNum & " Pit OUT"
        .Location = New Point(225, 200)
        .Height = 60
        .Width = 188
        .Font = New Font("Arial Rounded", 16, FontStyle.Bold)



    End With
    With NewLab1
        .BackColor = Color.Black
        .ForeColor = Color.Lime
        .Location = New Point(537, 200)
        .Height = 60
        .Width = 188
        .Font = New Font("Arial Rounded", 16, FontStyle.Bold)
        .TextAlign = ContentAlignment.MiddleCenter
        .Text = "Pit Stop Timer"

    End With

    With NewLab2
        .BackColor = Color.Black
        .ForeColor = Color.Lime
        .Location = New Point(748, 200)
        .Height = 60
        .Width = 188
        .Font = New Font("Arial Rounded", 16, FontStyle.Bold)
        .TextAlign = ContentAlignment.MiddleCenter
        .Text = "Stint Timer"

    End With
    With NewLab3
        .BackColor = Color.Black
        .ForeColor = Color.Lime
        .Location = New Point(953, 200)
        .Height = 60
        .Width = 188
        .Font = New Font("Arial Rounded", 16, FontStyle.Bold)
        .TextAlign = ContentAlignment.MiddleCenter
        .Text = "Timer 3"

    End With




    Controls.Add(NewBut1)
    Controls.Add(NewBut2)
    Controls.Add(NewLab1)
    Controls.Add(NewLab2)
    Controls.Add(NewLab3)



End Sub

Private Sub Timer2_Tick(sender As Object, e As EventArgs) Handles Timer2.Tick
    Dim NewLab1 As Label
    NewLab1.Text = Format(ss1, "00:") & Format(tt1, "00:") & Format(vv1, "00.") & Format(ww1, "00.")
    vv1 = vv1   1
    If vv1 > 59 Then
        vv1 = 0
        tt1 = tt1   1
    End If
    If tt1 = 2 Then
        vv1 = 0
        tt1 = 0
        Label1.Text = "00:00:00.00"
        Timer2.Enabled = False
        MessageBox.Show("time ended")
    End If
End Sub

Private Sub NewBut1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
    Timer2.enabled = True

End Sub


Private Sub Button21_Click(sender As Object, e As EventArgs) Handles Button21.Click
    Timer1.Enabled = True

End Sub
Sub newlab1()

End Sub

End Class

CodePudding user response：

Here's how the code should look:

Sub Main
    
End Sub

' Define other methods and classes here
Public Class Form1
    ReadOnly MyForm As Form
    Dim ss, tt, vv As Integer
    Dim ss1, tt1, vv1, ww1 As Integer

    Dim NewBut1 As Button
    Dim NewBut2 As Button
    Dim NewLab1 As Label
    Dim NewLab2 As Label
    Dim NewLab3 As Label

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Timer3.Enabled = True
        ' NewBut1()
    End Sub

    Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
        Label3.Text = Format(ss, "00:") & Format(tt, "00:") & Format(vv, "00")
        vv = vv   1
        If vv > 59 Then
            vv = 0
            tt = tt   1
        End If
        If tt = 2 Then
            vv = 0
            tt = 0
            Label3.Text = "00:00:00"
            Timer1.Enabled = False
            MessageBox.Show("time ended")
        End If
    End Sub

    Private Sub Timer3_Tick(sender As Object, e As EventArgs) Handles Timer3.Tick
        Label2.Text = Format(Now, "hh:mm:ss")
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        CarNum = InputBox("Add Car Number", "Car Number")

        With NewBut1
            .BackColor = Color.Red
            .ForeColor = Color.White
            .Text = "Car " & CarNum & " Pit IN"
            .Location = New Point(12, 200)
            .Height = 60
            .Width = 188
            .Font = New Font("Arial Rounded ", 16, FontStyle.Bold)
            AddHandler NewBut1.Click, AddressOf NewBut1_Click
        End With
        
        With NewBut2
            .BackColor = Color.Lime
            .ForeColor = Color.Black
            .Text = "Car " & CarNum & " Pit OUT"
            .Location = New Point(225, 200)
            .Height = 60
            .Width = 188
            .Font = New Font("Arial Rounded", 16, FontStyle.Bold)
        End With

        With NewLab1
            .BackColor = Color.Black
            .ForeColor = Color.Lime
            .Location = New Point(537, 200)
            .Height = 60
            .Width = 188
            .Font = New Font("Arial Rounded", 16, FontStyle.Bold)
            .TextAlign = ContentAlignment.MiddleCenter
            .Text = "Pit Stop Timer"
        End With

        With NewLab2
            .BackColor = Color.Black
            .ForeColor = Color.Lime
            .Location = New Point(748, 200)
            .Height = 60
            .Width = 188
            .Font = New Font("Arial Rounded", 16, FontStyle.Bold)
            .TextAlign = ContentAlignment.MiddleCenter
            .Text = "Stint Timer"
        End With

        With NewLab3
            .BackColor = Color.Black
            .ForeColor = Color.Lime
            .Location = New Point(953, 200)
            .Height = 60
            .Width = 188
            .Font = New Font("Arial Rounded", 16, FontStyle.Bold)
            .TextAlign = ContentAlignment.MiddleCenter
            .Text = "Timer 3"
        End With

        Controls.Add(NewBut1)
        Controls.Add(NewBut2)
        Controls.Add(NewLab1)
        Controls.Add(NewLab2)
        Controls.Add(NewLab3)

    End Sub

    Private Sub Timer2_Tick(sender As Object, e As EventArgs) Handles Timer2.Tick
        NewLab1.Text = Format(ss1, "00:") & Format(tt1, "00:") & Format(vv1, "00.") & Format(ww1, "00.")
        vv1 = vv1   1
        If vv1 > 59 Then
            vv1 = 0
            tt1 = tt1   1
        End If
        If tt1 = 2 Then
            vv1 = 0
            tt1 = 0
            Label1.Text = "00:00:00.00"
            Timer2.Enabled = False
            MessageBox.Show("time ended")
        End If
    End Sub

    Private Sub NewBut1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
        Timer2.enabled = True
    End Sub


    Private Sub Button21_Click(sender As Object, e As EventArgs) Handles Button21.Click
        Timer1.Enabled = True
    End Sub
    
End Class

Note there are class-level references to the dynamic elements you're creating.

Keep in mind that you probably shouldn't be creating those items everytime you click Button2.