android - download a json data to a recyclerview into a fragment -

i have been working android application , using 2 tabs have created 1 fragment each , want display recyclerview fragments. problem is, when download json data server, data downloaded lost. can not see in recyclerview. have tried many times nothing happend. here code:

this fragment: public class noticia extends fragment {      @override     public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) {         // inflate layout fragment         view view = inflater.inflate(r.layout.noticia, container, false);         recyclerview = (recyclerview)              view.findviewbyid(r.id.noticiasrecyclerview);         recyclerview.setlayoutmanager(new linearlayoutmanager(getactivity()));         buscanoticia();         return view;     }     private void buscanoticia() {         new noticiaasynctask().execute();     }  class noticiaasynctask extends asynctask<string, string, string> {         @override         protected void onpreexecute() {             super.onpreexecute();             pdialog = new progressdialog(getactivity());             pdialog.setmessage("aguarde...");             pdialog.setindeterminate(false);             pdialog.setcancelable(false);             pdialog.show();         }          @override         protected string doinbackground(string... params) {             jsonparse jsonparse = new jsonparse();             jsonobject jsonobject = jsonparse.makehttprequest(url, "post");              log.d("dados retornados: ", jsonobject.tostring());              arraylist = new arraylist<>();              try {                 sucesso = jsonobject.getint("sucesso");                 if (sucesso == 1) {                     jsonarray = jsonobject.getjsonarray("noticias");                      (int = 1; <= jsonarray.length(); i++) {                         jsonobject dadosjson = jsonarray.getjsonobject(i);                          noticiaitem noticiaitem = new noticiaitem();                          noticiaitem.settitulo(dadosjson.getstring("titulo"));                         noticiaitem.setnoticia(dadosjson.getstring("noticia"));                         noticiaitem.setdata(simpledateformat.parse(dadosjson.getstring("dados")));                         noticiaitem.setcategoria(dadosjson.getstring("categoria"));                         // adiciona na lista                         arraylist.add(noticiaitem);                     }                 }             } catch (jsonexception e) {                 e.printstacktrace();             } catch (parseexception e) {                 e.printstacktrace();             }             return null;         }          @override         protected void onpostexecute(string s) {             getactivity().runonuithread(new runnable() {                 @override                 public void run() {                   noticiaadapter = new noticiaadapter(getactivity(), arraylist);                   recyclerview.setadapter(noticiaadapter);                 }             });         }     }  }   , here adapter: public class noticiaadapter extends recyclerview.adapter<noticiaadapter.myviewholder> {      // inflator recyclerview layout     private context context;     private list<noticiaitem> list;      // construtor     public noticiaadapter(context context, list<noticiaitem> list) {         this.context = context;         this.list = list;     }      @override     public myviewholder oncreateviewholder(viewgroup parent, int viewtype) {         view view = layoutinflater.from(parent.getcontext()).inflate(r.layout.recyclerview, null);         myviewholder myviewholder = new myviewholder(view);         return myviewholder;     }      @override     public void onbindviewholder(myviewholder holder, int position) {         // esta eh informacao que vem banco. pego e seto no textviews dentro recyclerview         noticiaitem noticia = list.get(position);          // setando os dados recyclerview         holder.titulo.settext(noticia.gettitulo());         holder.paragrafo.settext(noticia.getnoticia());         holder.hora.settext(string.valueof(noticia.getdata()));         holder.categoria.append(noticia.getcategoria());     }      @override     public int getitemcount() {         return (null != list ? list.size() : 0);     }      static class myviewholder extends recyclerview.viewholder {         // recyclerview widgets         protected imageview imagem;         protected textview titulo;         protected textview paragrafo;         protected textview hora;         protected textview categoria;          public myviewholder(view itemview) {             super(itemview);             this.imagem = (imageview) itemview.findviewbyid(r.id.image_noticia);             this.titulo = (textview) itemview.findviewbyid(r.id.titulo_noticia);             this.paragrafo = (textview) itemview.findviewbyid(r.id.paragrafo_noticia);             this.hora = (textview) itemview.findviewbyid(r.id.hora_noticia);             this.categoria = (textview) itemview.findviewbyid(r.id.categoria_noticia);         }     } }  , json data trying download is: { noticias: [ { id: "1", titulo: "titulo noticia", noticia: "noticia nova", data: "2015-07-18", categoria: "1" }, { id: "2", titulo: "titulo noticia", noticia: "noticia nova", data: "2015-07-18", categoria: "1" }, { id: "3", titulo: "titulo noticia", noticia: "noticia nova", data: "2015-07-18", categoria: "1" }, { id: "4", titulo: "importante", noticia: "mova noticia importante", data: "2015-07-20", categoria: "2" } ], sucesso: 1 }  don't  know whats can wrong here. please 

remove runonuithread onpostexecute on same thread update ui there. more info check here android aynctask