help with Threading with textboxes

Question

hi im new here. i have a thread with textboxes i have invoker which invokes when it is required. when it invokes the text was able to show but if it doesn't require invoke i just wrote textbox1.Text += thestring; but the textbox was unable to show anyone know how to solve it? my textbox code it's under a function where my thread calls it. public void updateit(string message) { if (txtrecieve.IsDisposed) return; if (txtrecieve.InvokeRequired) { invoker = new GeneralDelegate(MethodRunningInMainThread); txtrecieve.Invoke(invoker new object[] { message }); } else { txtrecieve.Text += message; } } my thread private void Listen() { Chat_Listen cl = new Chat_Listen(l2); while (true) { myport = cl.returnport(); string message = cl.Listen(pass salt init); string[] part = message.Split(';'); if (part[0] == sendmsg2) { string username = part[2].ToString() + : + part[3].ToString(); string msgRecieve =  Says:  + part[1].ToString(); string message1 = username + msgRecieve; updateit(message1); } } } the one that activates the thread private void Chat_Load(object sender EventArgs e) { if (!this.IsHandleCreated) { lock (this) { this.CreateHandle(); this.CreateControl(); this.CreateGraphics(); } } dp_local.Image = local; //dp_remote.Image = remoteimg; this.Text = Talking to:  + remoteNickname; Sender = new Thread(new ThreadStart(Send)); Listener = new Thread(new ThreadStart(Listen)); //Listener.IsBackground = true; Listener.Start(); } thanks.

Alan · Answer

If the problem appears to be that the textbox handle hasn't yet been created then if InvokeRequired returns false I'd first check that this is in fact the case by calling the textbox's IsHandleCreated property. If this is false you can then force the handle to be created by simply accessing it: IntPtr hWnd = textbox1.Handle; It's then safe to set the textbox's Text property using Invoke or BeginInvoke.

Wallance Toh · Answer

i thought that i didn't dispose objects that's why the text didn't show up i close the form(like you said it's not been disposed) so i thought that during invoke false when i invoke the message inside my textbox it should be invoked to the old object since each time i show the form i used form1 f = new form1();

Alan · Answer

If the form is modal (i.e. a dialog) then when you close it with the X button it doesn't actually dispose of the form but just hides it. You can then reshow it by calling ShowDialog() again. However if you call Dispose() on the dialog it will destroy the form object (when the GC gets around to it) and so you'll need to create another instance of the dialog before reshowing it. If the form is modeless then closing it also disposes of it.

Wallance Toh · Answer

i've tried beginInvoke but still it's the same i was wondering whenever i close a form i didn't dispose the objects if i use this.dispose(); then i try showing the form again it gets unable to access disposed object.

Alan · Answer

My only other suggestion is to try the asynchronous BeginInvoke rather than Invoke.

Wallance Toh · Answer

well now at least handle is solved but still the textbox require invoke = false. example user 1 chats with user 2 user 2 chat window pop up.(invoke require = true) user 2 closes the chat window. user 1 chats with user 2 again user 2 chat window pop up (invoke require = false) and handles been force created and after force created i invoke the textbox yet the textbox don show any text. im still figuring how to solve this help will be appreciate..

Wallance Toh · Answer

it turns out to be require invoke turns out false sometimes and i found out that my thread works so quickly before my controls handle was created so anyone have a go about solving this? thanks

Alan · Answer

I don't know why InvokeRequired should return false when it really should be true unless there's some problem with the textbox handle. However it will do no harm to always use Invoke when changing the state of a UI element from another thread which is what I tend to do whether it's needed or not.