Question

OnContentRendred将启动许可证检查，如果没有有效许可证，我将提供LicenseWindow来选择一个。如果用户在未选择有效许可证的情况下关闭LicenseWindow，MainWindow也将关闭。

这是OnContentRendred的处理程序 - MainWindow的事件：

    private void CheckLicenseOnContentRendered(object sender, EventArgs e)
    {
        ContentRendered -= CheckLicenseOnContentRendered;
        try
        {
            Initialize(); // may throw LicenseException
        }
        catch (LicenseException)
        {
            var licenseWindow = new LicenseWindow();
            if (licenseWindow.ShowDialog() == true)
            {
                // Do Stuff if valid License selected
            }
            else
            {
                this.Close(); // <-- NullReferenceException
            }
        }
        catch (Exception ex)
        {
            // Other Exceptions will be handled here
        }

    }

在代码示例中标记this.Close()会产生NullReferenceException。

我做了一些调试，并使用ImmediateWindow我设法发现this不为空（应该是）

那么为什么this.Close()可能导致NullReferenceException，也许我如何以其他方式关闭窗口？

编辑： 堆栈跟踪：

   bei Giag.DataReader.ControlLibrary.Windows.MainWindow.WindowClosing(Object sender, EventArgs e) in d:\...\Windows\MainWindow.xaml.cs:Zeile 210.
   bei System.Windows.Window.OnClosing(CancelEventArgs e)
   bei System.Windows.Window.WmClose()
   bei System.Windows.Window.WindowFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   bei System.Windows.Interop.HwndSource.PublicHooksFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
  bei MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   bei MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
  bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
  bei MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
  bei System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
  bei MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
  bei MS.Win32.UnsafeNativeMethods.UnsafeSendMessage(IntPtr hWnd, WindowMessage msg, IntPtr wParam, IntPtr lParam)
  bei System.Windows.Window.InternalClose(Boolean shutdown, Boolean ignoreCancel)
  bei System.Windows.Window.Close()
  bei Giag.DataReader.ControlLibrary.Windows.MainWindow.CheckLicenseOnContentRendered(Object sender, EventArgs e) in d:\...\Windows\MainWindow.xaml.cs:Zeile 236.
   bei System.Windows.Window.OnContentRendered(EventArgs e)
   bei System.Windows.Window.<PostContentRendered>b__4(Object unused)
   bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   bei MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
   bei System.Windows.Threading.DispatcherOperation.InvokeImpl()
   bei System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state)
   bei System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   bei System.Windows.Threading.DispatcherOperation.Invoke()
   bei System.Windows.Threading.Dispatcher.ProcessQueue()
   bei System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   bei MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled)
   bei MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o)
   bei System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   bei MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
   bei System.Windows.Threading.Dispatcher.LegacyInvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs)
   bei MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam)
   bei MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg)
   bei System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   bei System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   bei System.Windows.Threading.Dispatcher.Run()
   bei System.Windows.Application.RunDispatcher(Object ignore)
   bei System.Windows.Application.RunInternal(Window window)
   bei System.Windows.Application.Run(Window window)
   bei System.Windows.Application.Run()
   bei FrameworkTestClient.App.Main() in d:\...\FrameworkTestClient\obj\Debug\App.g.cs:Zeile 0.
   bei System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   bei System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
   bei Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   bei System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   bei System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   bei System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   bei System.Threading.ThreadHelper.ThreadStart()

编辑2：

在测试项目中，上面的代码运行正常..所以我需要在其他地方找到Fault。谢谢你的帮助，我会让你联系。

Answer 1

不确定我是否正确理解了您的问题，但如果您想在未找到许可证的情况下退出整个程序，则可以使用Application.Current.Shutdown();关闭主窗口并退出应用程序。

Answer 2

Closing事件处理程序中存在错误。

有时人们会正确学习调试...... 谢谢大家。

如何关闭OnWindowRendred事件处理程序中的窗口？

2 个答案: