Question

我想知道我可以在下面第一个if语句的第二部分输入什么代码，以便在单击“取消”按钮时保持表单处于活动状态。

Private Sub ExitToolStripMenuItem_Click(sender As Object, e As EventArgs) Handles ExitToolStripMenuItem.Click
    'Message prompt to ask if the user really want to exit
    MsgBox("Are you sure you want to exit?", MsgBoxStyle.OkCancel, "MDCS")

    If MsgBoxResult.Ok Then
        If Application.OpenForms().OfType(Of Find_Client).Any Or Application.OpenForms().OfType(Of Form_items).Any Then
            MsgBox("Close all opened windows before the main", MsgBoxStyle.OkOnly, "MDCS")
        Else
            ' Call sub that close the program
            Me.Close()
            Dim items As New Form_items, clients As New Find_Client
            items.Close()
            clients.Close()
            'Stop Stopwatch
            Timer1.Stop()
            Me.StopWatch.Stop()

            'Mark Stopwatch value
            intTimerValues = Val(Timer_Label.Text)
        End If
    Else
        ???
    End If
End Sub

Answer 1

通常情况下，当前活动表单应自动显示，但如果您将代码放在特定的按钮事件处理程序中，则不会在Else函数中放置任何代码。在上面的评论中阅读你的回复后，我认为你将代码放在 Form_Closing 事件中，如果是这样，那么你应该把 e.Cancel（） 在代码的其他部分。

Answer 2

您拥有的代码不正确。

您会显示一个消息框

'Message prompt to ask if the user really want to exit
MsgBox("Are you sure you want to exit?", MsgBoxStyle.OkCancel, "MDCS")

但你没有测试它的返回值。

实际所做的是测试常量的值，MsgBoxResult.Ok

If MsgBoxResult.Ok Then

MsgBoxResult.Ok is a member of an enumeration评估为1.基本上，你所拥有的是

If 1 Then

好吧，总是评估为True，因此始终会运行If块。你永远不会进入Else区块。

通过实际测试MsgBox调用的结果来修复代码：

Dim MsgBoxResult As result = MsgBox("Are you sure you want to exit?", _
                                    MsgBoxStyle.OkCancel, _
                                    "MDCS")
If result = MsgBoxResult.Ok Then
    ' ...
    'Close the form.
    Me.Close()
Else
    ' ...
    ' Don't write code to close the form and it won't be closed.
End If

如果取消按钮单击VB 2012，则保持表单打开

2 个答案: