如何在选择阵列组合框时显示说明

Question

我如何使用这个昏暗的句柄作为我需要处理newpritemnobox的列表。那就是当我从newpritemnobox组合框中选择时，在某些选择newpritemnobox中包含podesc将显示

  Public Class POfrm
        Dim newpritemnobox As New List(Of ComboBox)
          Dim newpodescbox As New List(Of RichTextBox)

        Private Sub controlall(ByVal controlcount As Integer)
            Dim boxpritemno As ComboBox
                Dim boxpodesc As RichTextBox
               For i As Integer = 1 To controlcount
                boxpritemno = New ComboBox
                boxpritemno.Size = New Drawing.Size(51, 21)
                boxpritemno.Location = New Drawing.Point(89, 542 + 58 * (i - 1))
                newpritemnobox.Add(boxpritemno)
                Me.Controls.Add(boxpritemno)
            Next

            For i As Integer = 1 To controlcount
                boxpodesc = New RichTextBox
                boxpodesc.Size = New Drawing.Size(442, 45)
                boxpodesc.Location = New Drawing.Point(323, 542 + 58 * (i - 1))
                newpodescbox.Add(boxpodesc)
                Me.Controls.Add(boxpodesc)
            Next

        End Sub

        Private Sub poitemno_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles poitemno.Click

            Dim msgboxresponse As MsgBoxResult

            msgboxresponse = MsgBox("Are You Sure of the number of Item you choose?Please Check Again", _
                                        MsgBoxStyle.Question + MsgBoxStyle.YesNo, Me.Text)
            If msgboxresponse <> MsgBoxResult.Yes Then

            Else
                controlall(Val(txtpoitemno.Text))
                txtpoitemno.Enabled = False
                poitemno.Enabled = False
                loadtrypritemno()
                Return
            End If

        End Sub

我想这是我的代码，但它既不显示错误也不显示

        Private Sub boxpounitprice_SelectedIndexChanged(ByRef boxpritemno As ComboBox)

            datab = "Select pritemno from prpo where pritemno = '" & boxpritemno.Text & "'"
            connDB()
            cmd = New OleDbCommand(datab, conn)

            Dim result As Object
            result = cmd.ExecuteScalar()

            If result IsNot Nothing Then
                boxpoqty.Text = result.ToString()
            End If
         End Sub


  Private Sub loadtrypritemno()
            Dim controlall As Integer = Val(txtpoitemno.Text)

            'start from 0 because it's 0-based index
            For i As Integer = 0 To controlall - 1
                '            addbuyer(Label(i), itemcode(i), boxes(i), qty(i), combo(i), statusboxes(i), Remarksboxes(i))
                boxpounitprice_SelectedIndexChanged(newpritemnobox(i))
                AddHandler newpritemnobox(i).SelectedIndexChanged, AddressOf boxpounitprice_SelectedIndexChanged
            Next
        End Sub
        Private Sub boxpounitprice_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs)
            Dim tb As ComboBox = CType(sender, ComboBox)
            tb.SelectAll()
            MsgBox()
        End Sub
        'Private Sub loadamounttext()

        '    ' addpo()
        'End Sub


        Private Sub loadprinaccountcode()
            Dim datab4 As String
            Dim cmd4 As OleDbCommand
            Try




                Dim ST As String = cmbprno.SelectedText
        End Sub
        Private Sub loadpritem(ByRef boxpritemno As ComboBox)
            Try

                datab = "Select pritemno from prpo where prno = '" & cmbprno.Text & "'"
                connDB()
                cmd = New OleDbCommand(datab, conn)
                dr = cmd.ExecuteReader(CommandBehavior.CloseConnection)
                boxpritemno.Items.Clear()

                Do While dr.Read = True
                    ' txtdepartadd.Items.Add(dr("Departmentname"))
                    boxpritemno.Items.Add(dr(0))


                Loop

            Catch ex As Exception
                MsgBox(ex.Message)
            Finally
                cmd.Dispose()
                conn.Close()

            End Try
        End Sub





    End Class

Answer 1

 Private Sub boxty()
        Dim controlall As Integer = Val(txtpoitemno.Text)

        For i As Integer = 0 To controlall - 1
            boxpounitprice_SelectedIndexChanged(newpritemnobox(i), newpoqtybox(i))
        Next
    End Sub


    Private Sub boxpounitprice_SelectedIndexChanged(ByRef boxpritemno As ComboBox, ByRef boxpoqty As TextBox)
        AddHandler boxpritemno.SelectedIndexChanged, AddressOf boxpritemno_selectedindex
    End Sub

    Private Sub boxtrytry(ByVal boxpritemno As ComboBox, ByRef boxpoqty As TextBox, ByRef boxpounit As ComboBox, ByRef boxpodesc As RichTextBox)
        Dim datab1 As String
        Dim cmd1 As OleDbCommand
        Dim datab2 As String
        Dim cmd2 As OleDbCommand
        Try

            datab = "Select prqty from prpo where pritemno = '" & boxpritemno.Text & "' and prno = '" & cmbprno.Text & "'"
            connDB()
            cmd = New OleDbCommand(datab, conn)

            Dim result As Object
            result = cmd.ExecuteScalar()

            If result IsNot Nothing Then
                '  txtendorsedby.Text = result.ToString()
                boxpoqty.Text = result.ToString()
            End If

            datab1 = "Select pruom from prpo where pritemno = '" & boxpritemno.Text & "' and prno = '" & cmbprno.Text & "'"
            connDB()
            cmd1 = New OleDbCommand(datab1, conn)

            Dim result1 As Object
            result1 = cmd1.ExecuteScalar()

            If result1 IsNot Nothing Then
                '  txtendorsedby.Text = result.ToString()
                boxpounit.Text = result1.ToString()
            End If
            datab2 = "Select prdesc from prpo where pritemno = '" & boxpritemno.Text & "' and prno = '" & cmbprno.Text & "'"
            connDB()
            cmd2 = New OleDbCommand(datab, conn)

            Dim result2 As Object
            result2 = cmd2.ExecuteScalar()

            If result2 IsNot Nothing Then
                '  txtendorsedby.Text = result.ToString()
                boxpodesc.Text = result2.ToString()
            End If

        Catch ex As Exception
            MsgBox(ex.Message)
        Finally
            cmd.Dispose()
            conn.Close()

        End Try

    End Sub

    Private Sub loadtrypritemno()
        '  MessageBox.Show("right")
        Dim controlall As Integer = Val(txtpoitemno.Text)

        For i As Integer = 0 To controlall - 1
            boxtrytry(newpritemnobox(i), newpoqtybox(i), newpounitbox(i), newpodescbox(i))

        Next

    End Sub