Question

为什么我的价格框会记住我之前输入的内容。我不希望这种情况发生。有什么建议？这是我的代码。有谁知道如何防止这种情况发生。我第二次在价格框中输入价格时会记住之前的金额。

  Private Sub ProductIDComboBox_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles cboProductIDLookup.SelectedIndexChanged


    'Test to determine if a product has been selected
    If cboProductIDLookup.SelectedIndex <> -1 Then

        'Store the selectedIndex to variable
        Dim RowInteger As Integer = cboProductIDLookup.SelectedIndex

        'Based on RowInteger, display values to TextBox controls
        'from the array named inventoryProduct
        txtProductID.Text = InventoryProduct(RowInteger).ProductIDString
        txtDescription.Text = InventoryProduct(RowInteger).DescriptionString
        txtQuantityAmount.Text = InventoryProduct(RowInteger).QuantityInteger.ToString("N0")
        txtPriceAmount.Text = InventoryProduct(RowInteger).PriceDecimal.ToString("C2")

    End If
    ' txtQuantityAmount.Focus()
    txtPriceAmount.Focus()
    txtPriceAmount.Clear()



End Sub


    Private Sub txtPriceAmount_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtPriceAmount.KeyPress


    '''''''' Check for the flag being set in the KeyDown event.
    If acceptableKey = False Then
        '''''''' Stop the character from being entered into the control since it is non-numerical.
        e.Handled = True
        Return
    Else
        '''''''' 'must be in first position            

        If e.KeyChar = Convert.ToChar(Keys.Back) Then

            If strCurrency.Length > 0 Then
                strCurrency = strCurrency.Substring(0, strCurrency.Length - 1)
            End If
        Else
            strCurrency = strCurrency & e.KeyChar
        End If

        If strCurrency.Length = 0 Then
            txtPriceAmount.Text = ""
        ElseIf strCurrency.Length = 1 Then
            txtPriceAmount.Text = "0.0" & strCurrency
        ElseIf strCurrency.Length = 2 Then
            txtPriceAmount.Text = "0." & strCurrency
        ElseIf strCurrency.Length > 2 Then
            txtPriceAmount.Text = strCurrency.Substring(0, strCurrency.Length - 2) & "." & strCurrency.Substring(strCurrency.Length - 2)
        End If
        txtPriceAmount.Select(txtPriceAmount.Text.Length, 0)

    End If
    e.Handled = True

End Sub

      Private Sub PurchaseToolStripMenuItem_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PurchaseToolStripMenuItem.Click

    'Test to determine if a product was found.
    If txtDescription.Text = String.Empty Then

        'Cannot purchase, product was not found
        MessageBox.Show("You must select a valid product before purchasing.", "Cannot Purchase", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
        txtProductID.Focus()
        txtProductID.SelectAll()
    Else
        'Can purchase the product

        Dim ProductString As String = txtProductID.Text.PadRight(12, " ") & "" & txtDescription.Text.PadRight(50, " ") & "" & txtQuantityAmount.Text.PadRight(7, " ") & "" & txtPriceAmount.Text.PadLeft(9, " ").ToString
        lstPurchaseItems.Items.Add(ProductString)

        ' Double.Parse(txtPriceAmount.Text).ToString("C2").PadLeft(9, " ")
        '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
        'Accumulate the total value of this customer order
        'and display it to the output box
        TotalDueDecimal += (txtPriceAmount.Text.ToString * txtQuantityAmount.Text)
        txtTotalDueAmount.Text = TotalDueDecimal.ToString("C2")


        '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''


        'Accumulate total sales by product to an array
        Dim IndexInteger As Integer = cboProductIDLookup.SelectedIndex
        ProductSalesTotalDecimal(IndexInteger) += (txtPriceAmount.Text * txtQuantityAmount.Text)

        'Here you can clear the form of product info if you think
        'that is a good way to do the processing
        cboProductIDLookup.SelectedIndex = -1
        txtProductID.Clear()
        txtDescription.Clear()
        txtPriceAmount.Clear()
        txtQuantityAmount.Clear()
        txtProductID.Focus()
    End If

End Sub

Answer 1

这通常发生在ASP.NET / web应用程序中（并且可以关闭）但是你的应用程序是一个winforms应用程序，所以除非你的系统中安装了一些第三方组件，否则不应该这样做。你需要关闭那个组件。

现在，您没有指定它发生的位置。如果它是一个下拉列表，那么是的，它将自动完成（部分Windows / IE设置）。如果它是一个文本框，那么就没有太多可解释的了。

要为下拉列表关闭它，请在设计器中将AutoCompleteMode设置为“none”。如果有自定义源绑定到文本框，则同样适用于文本框。

这也很有趣：

 txtPriceAmount.Text = InventoryProduct(RowInteger).PriceDecimal.ToString("C2")

这也可能是问题，也许你的RowInteger没有在你的代码中正确更新，因此你认为它记得以前的输入，但实际上它只是错误的索引。

Answer 2

keypress事件中的代码很可能是罪魁祸首。说出程序，看看它是否消失。

由于strCurrency未在该过程中声明，因此它必须具有更大的scope，因此它会从上次“记住”（特别是因为您未在过程中初始化它）。

规则＃32 == LESS代码更好。

规则32a ==几乎在您跟踪用户的击键时，您要么解决错误的问题，要么以错误的方式解决问题。

编辑：

正如安德鲁所说，这也是错误的：

ProductSalesTotalDecimal(IndexInteger) += _
       (txtPriceAmount.Text * txtQuantityAmount.Text)

就像你不能多次“玩”时“自行车”一样，你不能将文本框的（字符串）内容加倍，即使它们中有数字。

为什么我的价格框会记住我之前输入的内容。我不希望这种情况发生。有什么建议？

2 个答案: