c# - Using ThreadStart my UI stuck -

i'm new threading ui not responding till completion of process. 1 tell me what's wrong here.

reduced code:

  static string replacedname = "", replacedwith;             private void startprocess(string fpath, string rno)             {                 if (fpath != "" && rno != "")                 {                     ....                      unzip(fpath, path.getdirectoryname(fpath) + "\\" + replacedwith);                      directoryinfo dir = new directoryinfo(path.getdirectoryname(fpath) + "\\" + replacedwith);                     foreach (fileinfo file1 in dir.getfiles("*.zip"))                     {                         unzip(file1.fullname, path.getdirectoryname(file1.fullname));                         file.delete(file1.fullname);                     }                  }                  replacedname = "";                 messagebox.show("completed");              }             private void button1_click(object sender, eventargs e)             {                  threadstart threadstart = delegate() { startprocess(textbox1.text, textbox2.text); };                  threadstart.begininvoke(null, null);               }             private void unzip(string ziptoextract, string unzipdirectoryl) // extract zip/lot file in same directory             {                  if (this.progressbar1.invokerequired)                 {                     progressbar1.invoke(new action(delegate() { unzip(ziptoextract, unzipdirectoryl); }));                  }                 else if (this.label3.invokerequired)                 {                     label3.invoke(new action(delegate() { unzip(ziptoextract, unzipdirectoryl); }));                 }                 else                 {                        ....                             progressbar1.value += 1;                             progressbar1.refresh();                             label3.text = ((progressbar1.value * 100) / (progressbar1.maximum)).tostring();                             label3.refresh();                         ...                 }             }               private void status(string msg, color selccolor)             {                 if (this.richtextbox1.invokerequired)                 {                     richtextbox1.invoke(new action(delegate() { status(msg, selccolor); }));                 }                 else                 {                     richtextbox1.selectionstart = richtextbox1.text.length;                     var oldcolor = richtextbox1.selectioncolor;                      richtextbox1.selectioncolor = selccolor;                     richtextbox1.appendtext(msg + "\n");                     richtextbox1.selectioncolor = oldcolor;                     richtextbox1.refresh();                     richtextbox1.scrolltocaret();                 }             } 

replace code

 private void button1_click(object sender, eventargs e)         {             threadstart threadstart = delegate() { startprocess(textbox1.text, textbox2.text); };             threadstart.begininvoke(null, null);         } 

with

 private void button1_click(object sender, eventargs e)         {             threadstart threadstart = delegate() { startprocess(textbox1.text, textbox2.text); };             thread thread = new thread(threadstart);             thread.start();         } 

this start new thread delegate assigned.
see here msdn reference.

edit

in unzip-method doing strange

private void unzip(string ziptoextract, string unzipdirectoryl){              if (this.progressbar1.invokerequired)             {                 progressbar1.invoke(new action(delegate() { unzip(ziptoextract, unzipdirectoryl); }));              }             else if (this.label3.invokerequired) // why else if on control???             {                 label3.invoke(new action(delegate() { unzip(ziptoextract, unzipdirectoryl); }));             }             else             {                        ....                         progressbar1.value += 1;                         progressbar1.refresh(); //why use refresh()?                         label3.text = ((progressbar1.value * 100) / (progressbar1.maximum)).tostring();                         label3.refresh();                     ...             }         } 

you can't call progressbar1.invokerequired , if returns false use else if on label-control! must use separate if/else every control.

if (this.progressbar1.invokerequired)      progressbar1.invoke(new action(delegate() { progressbar1.value++; })); else       progressbar1.value++; //pseudo-code