winforms - Dynamic Filling of TextBox AutoComplete not working is it possible in c#? -

i did put code in “textchanged”-event, think it's 'too late' there:

private void texttiteulttest_textchanged(object sender, eventargs e) {            textbox tb = (textbox)sender;           datalayer dbclass = new datalayer();            try {              string sql = ;             string strvar = texttiteulttest.text + "%";              //get sqldatareader dataclass             sqldatareader sqldr = dbclass.returndatareader(sql, , strvar);             autocompletestringcollection autocol = new autocompletestringcollection();              //fill stringcollection             while (sqldr.read()) {               autocol.add(sqldr["tite_titles"].tostring());             }              //fill autocomplete textbox             lock (tb.autocompletecustomsource.syncroot) {               tb.autocompletecustomsource = autocol;             }           }            catch (exception exc) {             console.writeline(exc.data.tostring() + exc.message.tostring());           }            {             //cleanup             dbclass.dispose();             console.writeline("'texttiteulttest_textchanged'");           }          }          error -> accessviolationexception:         "attempted read or write protected memory. indication other memory corrupt."         data: {system.collections.listdictionaryinternal}           not in try/catch-block, here:               static class program             {                 /// <summary>                 /// main entry point application.                 /// </summary>                 [stathread]                 static void main()                 {                     application.enablevisualstyles();                     application.setcompatibletextrenderingdefault(false);                     application.run(new form1());                 }             } 

so think, while i'm typing textbox code textchangded-event filling autocomplete-stringcollection in 1 thread , internal textbox-method/function needs read autocomplete-stringcollection @ same time in different thread.

the locking of syncroot doesn’t @ all, i’m not sure if made right in case.

also have code works , crashes. think depends on speed of getting sql server resultset.

so possiable ?

i go through link1 , link2 not answer yet please solve out this

the exact error getting this: system.accessviolationexception attempted read or write protected memory. indication other memory corrupt.

stack trace error system.accessviolationexception: attempted read or write protected memory. indication other memory corrupt. @ icsharpcode.texteditor.textarea.handlekeypress(char ch) @ icsharpcode.texteditor.textarea.simulatekeypress(char ch) @ icsharpcode.texteditor.textarea.onkeypress(keypresseventargs e) @ system.windows.forms.control.processkeyeventargs(message& m) @ system.windows.forms.control.processkeymessage(message& m) @ system.windows.forms.control.wmkeychar(message& m) @ system.windows.forms.control.wndproc(message& m) @ system.windows.forms.control.controlnativewindow.onmessage(message& m) @ system.windows.forms.control.controlnativewindow.wndproc(message& m) @ system.windows.forms.nativewindow.callback(intptr hwnd, int32 msg, intptr wparam, intptr lparam)

system.accessviolationexception: attempted read or write protected memory. indication other memory corrupt.    @ system.windows.forms.unsafenativemethods.callwindowproc(intptr wndproc, intptr hwnd, int32 msg, intptr wparam, intptr lparam)    @ system.windows.forms.nativewindow.defwndproc(message& m)    @ system.windows.forms.control.defwndproc(message& m)    @ system.windows.forms.control.wndproc(message& m)    @ system.windows.forms.textboxbase.wndproc(message& m)    @ system.windows.forms.richtextbox.wndproc(message& m)    @ system.windows.forms.control.controlnativewindow.onmessage(message& m)    @ system.windows.forms.control.controlnativewindow.wndproc(message& m)    @ system.windows.forms.nativewindow.callback(intptr hwnd, int32 msg, intptr wparam, intptr lparam) 

bind textbox during form load instead of textchanged event.textbox automatically show filterd suggestion entered user.

    list<string> s = new list<string>();     s.add("abc");     s.add("aaa");     s.add("acb");                 textbox1.autocompletemode = autocompletemode.suggest;     textbox1.autocompletesource = autocompletesource.customsource;     autocompletestringcollection data = new  autocompletestringcollection();     data.addrange(s.toarray());      textbox1.autocompletecustomsource = data;