.net – 应用程序不清除表单关闭时的对话框内容

跟我们一起,我是VB的新手.长话短说.我有一个VB应用程序,有几个按钮打开一个新的表单.我尝试使用Case选择将此表单重新用于多种用途.

2个按钮：

btnPing：

Private Sub btnPing_Click(sender As Object,e As EventArgs) Handles btnPing.Click
    dataTransferBtnCase = "ping"
    formDataTransfer.ShowDialog()
    btnRobocopy.Enabled = True
End Sub

和btnRobocopy

Private Sub btnRobocopy_Click(sender As Object,e As EventArgs) Handles btnRobocopy.Click
    dataTransferBtnCase = "robocopy"
    formDataTransfer.Show()
End Sub

在每个按钮中,它将值分配给变量dataTransferBtnCase.

现在,在该表单上,我有以下代码：

Public Class formDataTransfer

    'Clear the variable right off the bat
    Public dataTransferBtnCase As String = ""

    Private Sub formDataTransfer_Load(sender As Object,e As EventArgs) Handles MyBase.Load

        Dim oldpath As String = viewInstall.txtOldHostname.Text
        Dim newPath As String = viewInstall.txtNewHostname.Text

        dataTransferBtnCase = viewInstall.dataTransferBtnCase

        Select Case dataTransferBtnCase
            Case "ping"
                Me.Text = "Pinging " & oldpath
                ExecuteCommand("cmd.exe","/D /c ping " & oldpath)
            Case "robocopy"
                Me.Text = "Robocopy from " & viewInstall.txtOldHostname.Text & " to " & viewInstall.txtNewHostname.Text
                ExecuteCommand("robocopy.exe","C:\temp\robo1 C:\temp\robo2 /E /XF file *.dat *.dat.log *.dat.log1 /log:robolog.log")
            Case Else
                Me.Text = "lol idk!"
                MessageBox.Show("An unkNown error has occurred!","ERROR",MessageBoxButtons.OK,MessageBoxIcon.Error)
        End Select

        dataTransferBtnCase = ""
        viewInstall.dataTransferBtnCase = ""

    End Sub
End Class

btnPing_Click子工作每次都应该工作.但是,btnRobocopy_Click子只有在您单击一次,关闭新窗体窗口并再次单击该按钮后才能工作.我确定这是因为我没有在某处正确清除变量,我只是不知道在哪里.有帮助吗？

解决方法

问题是您使用对话框的方式：

Private Sub btnPing_Click(sender As Object,e As EventArgs) Handles btnPing.Click
    dataTransferBtnCase = "ping"
    formDataTransfer.ShowDialog()
    btnRobocopy.Enabled = True
End Sub

如果你使用ShowDialog,你也应该在之后处理它.按原样,您将重新显示旧实例,所有旧数据仍然存在.

在这方面,对话与常规表格不同.当我们完成一个表单并关闭它时,NET为我们处理了一些事情.对话框通常不会关闭(通常只是隐藏),因此我们可以从中获取信息.

这将创建一个新的表单实例,显示它然后在完成后处理它：

Dim dlgR As DialogResult
Using dlg As New formDataTransfer
   ' use a public property maybe to pass the data
   dlg.ActionToTake = "ping"

   dlgR  = dlg.ShowDialog()
   ' ... do stuff
End Using      ' dispose of the dialog

由于表单不会自动处理 – 您可能只有隐藏它的代码 – 您正在重用最后一个实例.

原文地址：https://www.jb51.cc/html/232048.html