json - Android: Indeterminate progress bar for ServerCall routine. -

i'm working on simple i.m android app class makes queries server , displays results (i.e messages) on listview. 1 of requirements app display indefinite progress bar while query being made. means have set progressbar widget view.visible when query begins , view.invisible when query over. trouble i'm having query background function defined in different java class, while i'd this:

        progressbar pb = (progressbar) findviewbyid(r.id.progressbar);         pb.setvisibility(view.visible);         ...         ...         uploader.execute(mycallspec);         ...         ...         pb.setvisibility(view.invisible); 

this doesn't work, because server call runs in background. using code, it's if progress bar never displayed.

how set progress bar displayed when service call begins , invisible when call completed?

go ahead asynctask

class mytask extends asynctask<void, void, void> {    private progressbar pb;    public mytask(progressbar pb) {       this.pb = pb;    }      @override     protected void onpreexecute() {       super.onpreexecute();       pb.setvisibility(view.visible);     }      @override     protected void doinbackground(void... params) {       //your query here.       return null;     }      @override     protected void onpostexecute(void result) {       super.onpostexecute(result);       pb.setvisibility(view.gone);     } }   mytask mt = new mytask(pb);  mt.execute() 

but in real project suggest use robospice. asynctask doesn't handle activity lifecycle default.

upd:

there 2 ways have access progressbar instance inside asynctask:

1. just declare inner class , save progressbar in field of outer (main) class
2. pass reference via constructor. (see modified example)