java - AsyncTask do not cancel on cancelling -

i have asynctasks. in oncreate view of dialog fragment creating object of asynctask below (sample code)

      @override      public view oncreateview(layoutinflater inflater, viewgroup container,bundle savedinstancestate) {    cashinvalidatorlistner = new cashinvalidatorlistner(msessionmanager.getcustomerid(),msessionmanager.getposid(), this);         } 

now in onclick executing async taks

  @override public void onclick(view v) {     if(v==ok)      {          if(mhomeactivity.mprogressdialog!=null && !mhomeactivity.mprogressdialog.isshowing()){             mhomeactivity.mprogressdialog.show();         }          cashinvalidatorlistner.execute();     }     } 

i have added oncancellistner progressbar

       @override public void oncancel(dialoginterface dialog) {      if(dialog==mprogressdialog)     {          mdialogextraoptions.cashinvalidatorlistner.cancel(true);         toast.maketext(getbasecontext(), "task cancled", toast.length_short).show();     } } 

the first time cancel async task cancelled howerver on executing again gives error saying can not execute task executed .

when tried creating object @ onclick each time user click ok button problem solved

        @override public void onclick(view v) {     if(v==ok)      {          if(mhomeactivity.mprogressdialog!=null && !mhomeactivity.mprogressdialog.isshowing()){             mhomeactivity.mprogressdialog.show();         }            cashinvalidatorlistner = new cashinvalidatorlistner(msessionmanager.getcustomerid(),msessionmanager.getposid(), this);          cashinvalidatorlistner.execute();     }     } 

here works fine ,my question why async task not executing when running second time in first case ?

you may execute asynctask once in instance's lifetime. solved creating new instance of asynctask object , executing newly created object, have done.

 (new cashinvalidatorlistner(msessionmanager.getcustomerid(),msessionmanager.getposid(), this)).execute();