control.BeginInvoke和control.Invoke执行时的问题！！！

Question

    public partial class MainForm : Form
    {
        private delegate void FileSearchStartDelegate(string path,string zifuchuan);
        private FileSearchStartDelegate FileSreachStart;        private delegate void FilesAddDelegate(string file);
        private FilesAddDelegate FilesAdd;        public MainForm()
        {
            InitializeComponent();            FileSreachStart = new FileSearchStartDelegate(StartSreachFile);
            FilesAdd = new FilesAddDelegate(AddFiles);  
        }
        /// <summary>
        /// 搜索指定目录，填充界面列表
         /// </summary>
        private void btSearch_Click(object sender, EventArgs e)
        {
            string path = this.tbMuLu.Text;
            string zifuchuan = this.tbString.Text;
            this.FileSearch(path, zifuchuan);
        }        private void FileSearch(string path,string zifuchuan)
        {
            this.BeginInvoke(FileSreachStart, new object[] { path, zifuchuan }); 
        }        private void StartSreachFile(string path, string zifuchuan)
        {
            for (int i = 0; i <= 1000000; i++)
            {
                string file =i.ToString()+ "a.txt";
                Application.DoEvents();
                this.Invoke(FilesAdd, new object[] { file });
            }            
        }        private void AddFiles(string file)
        {
            this.FileListLB.Items.Add(file);   
        }
    }
这并不是一个多线程问题，但是为什么在填充界面的时候，点击退出，会发生错误？
错误提示：
未处理 System.Reflection.TargetInvocationException
  Message="调用的目标发生了异常。"
  Source="mscorlib"
  StackTrace:
       在 System.RuntimeMethodHandle._InvokeMethodFast(Object target, Object[] arguments, SignatureStruct& sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
       在 System.RuntimeMethodHandle.InvokeMethodFast(Object target, Object[] arguments, Signature sig, MethodAttributes methodAttributes, RuntimeTypeHandle typeOwner)
       在 System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture, Boolean skipVisibilityChecks)
       在 System.Delegate.DynamicInvokeImpl(Object[] args)
       在 System.Windows.Forms.Control.InvokeMarshaledCallbackDo(ThreadMethodEntry tme)
       在 System.Windows.Forms.Control.InvokeMarshaledCallbackHelper(Object obj)
       在 System.Threading.ExecutionContext.runTryCode(Object userData)
       在 System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData)
       在 System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
       在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       在 System.Windows.Forms.Control.InvokeMarshaledCallback(ThreadMethodEntry tme)
       在 System.Windows.Forms.Control.InvokeMarshaledCallbacks()
       在 System.Windows.Forms.Control.WndProc(Message& m)
       在 System.Windows.Forms.ScrollableControl.WndProc(Message& m)
       在 System.Windows.Forms.ContainerControl.WndProc(Message& m)
       在 System.Windows.Forms.Form.WndProc(Message& m)
       在 System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
       在 System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
       在 System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
       在 System.Windows.Forms.UnsafeNativeMethods.DispatchMessageW(MSG& msg)
       在 System.Windows.Forms.Application.ComponentManager.System.Windows.Forms.UnsafeNativeMethods.IMsoComponentManager.FPushMessageLoop(Int32 dwComponentID, Int32 reason, Int32 pvLoopData)
       在 System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)
       在 System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)
       在 System.Windows.Forms.Application.Run(Form mainForm)
       在 多线程测试.Program.Main() 位置 E:\测试\多线程测试\多线程测试\Program.cs:行号 17
       在 System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
       在 System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       在 Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       在 System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       在 System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       在 System.Threading.ThreadHelper.ThreadStart()
不是很明白为什么会这样？期盼各位高人的答复！

Answer 1

BeginInvoke 是典型的异步操作，怎么会不是多线程呢

Answer 2

没必要BeginInvoke
public   partial   class   MainForm   :   Form 
        { 
                public   MainForm() 
                { 
                        InitializeComponent();    
                } 
                ///   <summary> 
                ///   搜索指定目录，填充界面列表 
                  ///   </summary> 
                private   void   btSearch_Click(object   sender,   EventArgs   e) 
                { 
                        string   path   =   this.tbMuLu.Text; 
                        string   zifuchuan   =   this.tbString.Text; 
                        this.FileSearch(path,   zifuchuan); 
                }                 private   void   FileSearch(string   path,string   zifuchuan) 
                { 
                        for   (int   i   =   0;   i   <=   1000000;   i++) 
                        { 
                                string   file   =i.ToString()+   "a.txt"; 
                                Application.DoEvents(); 
                                this.FileListLB.Items.Add(file);   
                        }     
                } 
        } 
这样做才应该是你要的效果