Problem with Threading and treeView.

Question

Hello everyone! ok so I have the following problem: (look at the buttom for error message) (check for comments to find whats wrong) private void connect() { try { socket = new Socket(AddressFamily.InterNetwork SocketType.Stream ProtocolType.Tcp); IPAddress ip = Dns.Resolve(irc.quakenet.org).AddressList[0]; socket.Connect(new IPEndPoint(ip 6667)); //The problem lays here.//////////////////// //////////////////////////////////////////// this.treeView1.Nodes.Add(Server); //////////////////////////////////////////// //////////////////////////////////////////// if(socket.Connected) { send(NICK  + strNick1); send(USER  + strNick1 +  8  +  *  + : + strFirst +   + strLast); recive(); } else this.richTextBox1.Text += Could not connect to server; } catch(Exception ex) { this.richTextBox1.Text += ex.Message + 
; } } connection() runs from the following lines of code: Thread thread1 = new Thread(new ThreadStart(connect)); thread1.Start(); The error message says the following: The action being performed on this control is being called from the wrong thread. You must marshal to the correct thread using Control.Invoke or Control.BeginInvoke to perform this action. I´ve never used Control.Invoke etc before so I would realy appreciate if anyone could help me get this thing working.

vladimir 0 · Answer

I hope this Helps ! Vladimir Sutskever Simplicato E-Mail Services Vladimir@Simplicato.com

vladimir 0 · Answer

ERROR:  The action being performed on this control is being called from the wrong thread. You must marshal to the correct thread using Control.Invoke or Control.BeginInvoke to perform this action.  The Only Thread that has access to TreeView control is the Main Form Thread where the control was created. In this example you are trying to modify the TreeView control from Thread Connect. To get arround this you should use the Invoke() or BeginInvoke() methods of the control. These two methods execute the modification of the TreeView from within the thread that actually owns the control. Here is a usage example: ############################################## using System; using System.Collections; using System.Windows.Forms; namespace connection { //declairing delegate UpdateTree that returs void and takes in no parameters delegate void UpdateTreeDelegate (); public class Connect { ArrayList folder_list= new ArrayList(); private System.Windows.Forms.TreeView treeview; //===================================== public Connect(System.Windows.Forms.TreeView treev){ treeview=tv; }//Constructor //===================================== public void GetFolderList(){ folder_list=folder_list.Add(Inbox); folder_list=folder_list.Add(Junk); UpdateTreeDelegate UTD = new UpdateTreeDelegate(LoadFolderToTree); }//function get folder list //===================================== public void LoadFolderToTree(){ this.treeview.Nodes.Clear(); foreach (string folder in folder_list){ treeview.Nodes.Add(folder); } }//Class Connect }//namespace connection

prabhukonnet · Answer

Hi You have to use treeView.BeginInvoke and call a custome delegate as shown below. This help you to perfom the opearation asyncronously. delegate void UpdateTreeDelegate1( Info[] data); String data=india; treeView.BeginInvoke(new UpdateTreeDelegate1(LoadData) new Object[] data }); LoadData(data) { } intailly u'r Main will complete and then LoadData is called frm the same thread. hope this sloves u'r problem bye Prabhu

haerry · Answer

Hi So here you are starting a new thread Thread thread1 = new Thread(new ThreadStart(connect)); thread1.Start(); in your connect function you make the following: this.treeView1.Nodes.Add(Server); Its' the topmost rule about threading you violated against: NO OTHER THREAD SHOULD UPDATE AN UI THEN THE THREAD WOH HAVE CREATED IT !!! Your treeview is created in the Initialize function (i guess) it's the main thread. Only this thread can update your treeview. look at msdn or codeproject for samples adressing this problem