Question

我试图引用创建的图片框的标签，然后删除访问表中的记录，该记录的ID对应于图片框的标签。但是，当我尝试引用图片框的标签时，我只会得到一个null引用异常错误。您认为您可以帮忙吗？

这是创建图片框的代码！现在我还无法测试，但是使用此代码，插入的第一张图片的标签应为1，第二张图片的标签应为2，第三张图片的标签为3，依此类推...

' Declared in Form1 (global)
Dim cardPictureBox As PictureBox

Public Sub bigpictureloader()
        Dim cardcount As Integer
        Dim cards As List(Of String) = New List(Of String)
        cards.Add(imageurltxt.Text)

        'Create a placeholder variable
        Dim cardPictureBox As PictureBox

        'Loop through every selected card URL
        For Each url As String In cards
            'Create a new PictureBox
            cardPictureBox = New PictureBox()
            cardPictureBox.Size = New Size(100, 100)
            cardPictureBox.SizeMode = PictureBoxSizeMode.Zoom
            cardPictureBox.WaitOnLoad = False
            AddHandler cardPictureBox.Click, AddressOf imagehandler
            cardcount = 0


            counter += 1
            cardcount = counter
            cardPictureBox.Tag = Convert.ToInt32(cardcount)
            'Add the PictureBox to the Form
            Me.Controls.Add(cardPictureBox)

            If imageurltxt.Text = "" Then
                cardPictureBox = Nothing
            Else

                cardPictureBox.LoadAsync(url)
                TableLayoutPanel1.Controls.Add(cardPictureBox, 0, 0)

            End If
            'Load the image asynchronously
            ' cardPictureBox.LoadAsync(url)
            'TableLayoutPanel1.Controls.Add(cardPictureBox, 0, 0)
        Next

    End Sub

这是删除数组记录的代码（这是图像处理程序）

Private Sub testdelete()
        'THIS SAVES TO THE DEBUG ACCESS DATABASE!!!!!
        Using conn As New OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source = FULL YUGIOH ACCESS DATABASE.accdb;")
            Using command As New OleDbCommand("Delete From cmon11 Where ID= @ID;", conn)
                command.Parameters.Add("@ID", OleDbType.Integer).Value = CInt(cardpicturebox.tag)
                conn.Open()
                command.ExecuteNonQuery()
            End Using
        End Using


    End Sub

引用手动添加的图片框的标记

0 个答案: