WaitForExit（）运行时异常。（等待cmd进程完成）

您能否告诉我为什么我在运行此代码时遇到运行时异常？WaitForExit（）运行时异常。（等待cmd进程完成）

Sub BtnNowClick(sender As Object, e As EventArgs) 

    Dim myProcess As New Process 
    Dim processFile As String = dlgFolder.SelectedPath 
    Dim pyLocationDel As String = Path.Combine(dlgFolder.SelectedPath, "pdfmerge.py") 

    Directory.SetCurrentDirectory(dlgFolder.SelectedPath) 

    myProcess.Start(pyLocationDel) 
    myProcess.WaitForExit()  
    System.IO.File.Delete(pyLocationDel) 


End Sub

基本上，我想要的是检测一个过程完成并删除一个特定的文件，如果过程完成。

System.NullReferenceException: Object reference not set to an instance of an object. 
    at lgaPDF.MainForm.BtnNowClick(Object sender, EventArgs e) in C:\Documents and Settings\student3\My Documents\SharpDevelop Projects\lgaPDF\lgaPDF\MainForm.vb:line 184 
    at System.Windows.Forms.Control.OnClick(EventArgs e) 
    at System.Windows.Forms.Button.OnClick(EventArgs e) 
    at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent) 
    at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks) 
    at System.Windows.Forms.Control.WndProc(Message& m) 
    at System.Windows.Forms.ButtonBase.WndProc(Message& m) 
    at System.Windows.Forms.Button.WndProc(Message& m) 
    at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) 
    at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) 
    at System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam) 
    at System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg) 
    at System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(IntPtr dwComponentID, Int32 reason, Int32 pvLoopData) 
    at System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context) 
    at System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context) 
    at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun() 
    at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel() 
    at Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine) 
    at lgaPDF.My.MyApplication.Main(String[] Args) in 17d14f5c-a337-4978-8281-53493378c1071.vb:line 81

来源

2011-08-29 Brian

因为你从来没有创建任何Process例如：

当试图执行的代码我得到这个错误。

您可以使用构造在声明varaible：

Dim myProcess As New Process()

设有独立的构造函数调用：

Dim myProcess As Process 
myProcess = New Process()

来源

2011-08-29 08:35:14 Guffa

谢谢你的提示，但是，我尝试过，但我得到一个新错误'System.InvalidOperationException：没有进程与此对象关联。' – Brian

我更新了问题中的代码。 – Brian

你不能像这样垃圾人的答案。开始一个新的问题。 –

WaitForExit（）运行时异常。 （等待cmd进程完成）

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WaitForExit（）运行时异常。（等待cmd进程完成）