Question

我正在使用visual C＃express 2008.当我尝试运行我的项目时，我有时会在我的invoke方法中获得非法的跨线程操作。它在许多地方使用相同的invoke方法，但它只在另一个线程的开头我得到错误。我检查InvokeRequired属性，调用相同的方法并在'else'条件下创建一个临时变量并为其分配我的控件文本。但是在那一行，在'else'语句中，在Invoking方法中，我有时会得到异常。可能是什么原因？如何摆脱它？它不会经常发生，但它仍然是一个错误。

代码：

// Delegate:
private delegate void ChangeTextDelegate(string text);

// Method:
public static void ChangeText(string text)
{
    if (richtextbox1.InvokeRequired)
    {
        richtextbox1.Invoke(new ChangeTextDelegate(ChangeText), new object[] { text });
    }
    else
    {
        int startIndex;
        startIndex = richtextbox1.TextLength; // <- Exception points here.
        // ...
    }
}

堆栈追踪：

System.InvalidOperationException was unhandled
  Message="Cross-thread operation not valid: Control 'SomeClass' accessed from a thread other than the thread it was created on."
  Source="System.Windows.Forms"
  StackTrace:
       at System.Windows.Forms.Control.get_Handle()
       at System.Windows.Forms.Control.get_InternalHandle()
       at System.Windows.Forms.Control.WmWindowPosChanged(Message& m)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.TextBoxBase.WndProc(Message& m)
       at System.Windows.Forms.RichTextBox.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.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam)
       at System.Windows.Forms.NativeWindow.DefWndProc(Message& m)
       at System.Windows.Forms.Control.DefWndProc(Message& m)
       at System.Windows.Forms.Control.WmCreate(Message& m)
       at System.Windows.Forms.Control.WndProc(Message& m)
       at System.Windows.Forms.TextBoxBase.WndProc(Message& m)
       at System.Windows.Forms.RichTextBox.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.IntCreateWindowEx(Int32 dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef hInst, Object pvParam)
       at System.Windows.Forms.UnsafeNativeMethods.CreateWindowEx(Int32 dwExStyle, String lpszClassName, String lpszWindowName, Int32 style, Int32 x, Int32 y, Int32 width, Int32 height, HandleRef hWndParent, HandleRef hMenu, HandleRef hInst, Object pvParam)
       at System.Windows.Forms.NativeWindow.CreateHandle(CreateParams cp)
       at System.Windows.Forms.Control.CreateHandle()
       at System.Windows.Forms.TextBoxBase.CreateHandle()
       at System.Windows.Forms.Control.get_Handle()
       at System.Windows.Forms.RichTextBox.get_TextLength()
       at SomeNamespace.SomeClass.Changetext(String text, Color color) in C:\...\SomeClass.cs:line 827
       at SomeNamespace.SomeClass.SomeThreadFun() in C:\...\SomeClass.cs:line 112
       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
       at System.Threading.ThreadHelper.ThreadStart()
  InnerException:

TY

Answer 1

问题似乎是您尝试从非UI线程访问Windows控件属性。相反，尝试使用Invoke从控件中获取文本长度。

非法的跨线程操作异常，无法处理它

1 个答案: