Question

    System.InvalidCastException was unhandled
  Message=Unable to cast object of type 'SportSoft.SSBLL.CMembershipTypeAdvanceBooking' to type 'SportSoft.SSBLL.CAreaActivities'.
  Source=SSDlgs
  StackTrace:
       at SportSoft.SSDlgs.frmAdvanced.ListChanged(Object sender, ListChangedEventArgs e) in C:\Documents and Settings\a_rahnema\My Documents\Visual Studio 2010\Projects\SSDlgs\Booking\frmAdvanced.vb:line 56
       at System.ComponentModel.ListChangedEventHandler.Invoke(Object sender, ListChangedEventArgs e)
       at SportSoft.SSBLL.CBOView.OnListChanged(ListChangedEventArgs e) in C:\Documents and Settings\a_rahnema\My Documents\Visual Studio 2010\Projects\SSBLL\BOView.vb:line 200
       at SportSoft.SSBLL.CBOView.AddNew() in C:\Documents and Settings\a_rahnema\My Documents\Visual Studio 2010\Projects\SSBLL\BOView.vb:line 680
       at System.Windows.Forms.CurrencyManager.AddNew()
       at System.Windows.Forms.DataGrid.AddNewRow()
       at System.Windows.Forms.DataGridAddNewRow.OnEdit()
       at System.Windows.Forms.DataGrid.Edit(String displayText)
       at System.Windows.Forms.DataGrid.OnEnter(EventArgs e)
       at System.Windows.Forms.Control.NotifyEnter()
       at System.Windows.Forms.ContainerControl.UpdateFocusedControl()
       at System.Windows.Forms.ContainerControl.AssignActiveControlInternal(Control value)
       at System.Windows.Forms.ContainerControl.ActivateControlInternal(Control control, Boolean originator)
       at System.Windows.Forms.ContainerControl.ActivateControlInternal(Control control)
       at System.Windows.Forms.Control.WmSetFocus(Message& m)
       at System.Windows.Forms.Control.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.SetFocus(HandleRef hWnd)
       at System.Windows.Forms.Control.FocusInternal()
       at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)
       at System.Windows.Forms.Control.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 System.Windows.Forms.Application.Run(Form mainForm)
       at SportSoft.ssBOffice.frmMain.Main() in C:\Documents and Settings\a_rahnema\My Documents\Visual Studio 2010\Projects\ssBOffice\Forms\frmMain.vb:line 0
       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

Answer 1

在frmAdvanced课程中，您有一个ListChangedEventHandler。在此方法的某个位置，您尝试将SportSoft.SSBLL.CMembershipTypeAdvanceBooking转换为SportSoft.SSBLL.CAreaActivities类型。这是不允许的。

Answer 2

看起来它说它无法投射'SportSoft.SSBLL.CMembershipTypeAdvanceBooking'类型的对象在frmAdvanced.vb的第56行输入'SportSoft.SSBLL.CAreaActivities'：）

Answer 3

在第56行的文件frmAdvanced.vb中，您要将CAreaActivities类型的变量设置为CMembershipTypeAdvanceBooking类型的值。

由于CMembershipTypeAdvanceBooking未从CAreaActivities继承，因此分配在运行时失败。

如果您需要其他帮助，请发布包含第56行的frmAdvanced.vb文本的一部分。

Answer 4

错误是说正在投射的对象无法转换为指定的类型。

请参阅：http://msdn.microsoft.com/en-us/library/system.invalidcastexception.aspx

Answer 5

它的说法：

无法投射类型的对象 'SportSoft.SSBLL.CMembershipTypeAdvanceBooking' 输入 'SportSoft.SSBLL.CAreaActivities'。

某处有些代码试图将CMembershipTypeAdvanceBooking对象转换为CAreaActivities对象并且不允许这样做。

奇怪的例外，这是什么意思？

5 个答案: