跨线程操作无效:尝试从列表框删除项目时 [英] Cross-thread operation not valid: while tried to remove item from Listbox

问题描述

跨线程操作无效:控制listbox1从与其在其上创建的线程不同的线程访问
我在ListBox中有代表ADD项目的委托.在添加新项目之前，我检查它是否已在列表中.如果是，则从列表中删除并添加新项目.


当我尝试删除旧项目时，它给出了错误.

跨线程操作无效:从不在其上创建线程的线程访问控件listbox1"


我不能在一次通话中同时进行这两项操作吗?

请帮我！！！ :(


谢谢
Seema

Cross-thread operation not valid: Control listbox1 accessed from a thread other than the thread it was created on

I have delegate for ADD items in ListBox. Before add new item I check is it already in the list If yes then Remove from the List and add new one.


As I tried to remove old item It gives error.

"Cross-thread operation not valid: Control listbox1 accessed from a thread other than the thread it was created on"


Can''t I do both operation together in single call??

Please help me!!! :(


Thank you
Seema

推荐答案

您应该只从创建UI元素的线程中访问UI元素

如何:对Windows窗体控件进行线程安全调用 [ ^ ]

使用列表框的"InvokeRequired"属性来查看是否需要编组回UI线程

例如

You should only access UI elements from the thread that created them

How to: Make Thread-Safe Calls to Windows Forms Controls [^]

Use the ''InvokeRequired'' property of your listbox to see if you need to marshal back to the UI thread

e.g.

private void LoadItems()
{
    // InvokeRequired required compares the thread ID of the
    // calling thread to the thread ID of the creating thread.
    // If these threads are different, it returns true.
    if (this.listbox1.InvokeRequired)
    {
        SetTextCallback d = new SetTextCallback(SetText);
        this.Invoke(d, new object[] { text });
    }
    else
    {
        // Load your items here
    }
}

另外，如果您使用的是.Net 4.0，则可能需要查看任务并行库 [ ^ ]，您可以使用使用延续并传递自动编组回UI的同步上下文

http://blogs. msdn.com/b/csharpfaq/archive/2010/06/18/parallel-programming-task-schedulers-and-synchronization-context.aspx [

Alternatively, if you''re using .Net 4.0, you might want to look at the Task Parallel Library[^] which allows you to use continuations and pass a Synchronization Context that automatically marshalls back to the UI

http://blogs.msdn.com/b/csharpfaq/archive/2010/06/18/parallel-programming-task-schedulers-and-synchronization-context.aspx[^]

Just noticed the .Net 3.5 tag! I''ll leave the TPL reference in my answer though, might help someone else

别忘了Google，您甚至在发布问题之前尝试在CP上找到答案.
我进行了google搜索，第一个结果是此 [

Leave alone Google, did you even try to find answer on CP before posting the question.
I did the google search and the first result was for this [^]on Code Project.

It explains it nicely.

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