android - Refreshing RequestQueue -

i have requestqueue i'm adding few urls string them. able refresh them on demand. used approach adding new (the same previous) requests queue, see isn't option. also, there possibility data network? never cache?

stringrequest stringrequest = new stringrequest(channel.getread_last_entry_url(),                 new response.listener<string>() {                     @override                     public void onresponse(string response) {                         channel.parse_json(response);                     }                 },                 new response.errorlistener() {                     @override                     public void onerrorresponse(volleyerror error) {                         toast.maketext(getactivity(), error.getmessage(), toast.length_long).show();                     }                 });         requestqueue requestqueue = volley.newrequestqueue(getactivity());         requestqueue.add(stringrequest);