Android Spinner's onItemSelected executed twice when going back to Fragment -

i created spinner fragment populates data retrieved http callout. when fragment first created, populate spinner selection choices, set setonitemselectedlistener , set initial selection in oncreateview().

    statespinner.setonitemselectedlistener(new adapterview.onitemselectedlistener() {          public void onitemselected(adapterview<?> parent, view view, int position, long id)         {               if (spinnerposition != position)             {                 spinnerposition = position;                 textview stateselected = (textview) view;                 string stateselectedstr = stateselected.gettext().tostring();                   linearlayout ballotsdisplay = (linearlayout) getactivity().findviewbyid(r.id.ballotsdisplay);                 ballotsdisplay.removeallviews();                  map<string, string> calloutparams = new hashmap<string, string>();                 calloutparams.put("state", stateselectedstr);                  // create , execute asynctask retrieve ballots                 new retrieveballots().execute(calloutparams);             }         }          public void onnothingselected(adapterview<?> parent) {             return;         }     });      // set default selection spinner     int defaultstate = adapter.getposition(userstate);      if (defaultstate == -1)     {         defaultstate = 0;     }      statespinner.setselection(defaultstate); 

when fragment created, works well, spinner position set default , spinner item selected once shown in log below:

5009-5009/com.project.test d/test﹕ oncreateview called 5009-5009/com.project.test d/test﹕ statespinner.setselection 5009-5009/com.project.test d/test﹕ onactivitycreated called 5009-5009/com.project.test d/test﹕ onresume called 5009-5009/com.project.test d/test﹕ spinner item selected 

the problem occurs when navigate away fragment fragment (i store fragment onto backstack). when click go original fragment, spinner seems have item selected twice:

5009-5009/com.project.test d/test﹕ oncreateview called 5009-5009/com.project.test d/test﹕ statespinner.setselection 5009-5009/com.project.test d/test﹕ onactivitycreated called 5009-5009/com.project.test d/test﹕ onresume called 5009-5009/com.project.test d/test﹕ spinner item selected 5009-5009/com.project.test d/test﹕ spinner item selected 

so have 2 questions:

1) why spinner register 2 item selection occurrences when returning button.

2) there fix prevent 2 item selections occurring? right fragment being populated duplicate data since retrieves data twice.

** edit ** after changing statespinner.setselection(defaultstate, false), null pointer exception @ ballotsdisplay.removeallviews(); seems ballotsdisplay set null reason change

stacktrace:

05-15 07:25:48.303 6153-6153/com.poliseewriters.polisee e/androidruntime﹕ fatal exception: main java.lang.nullpointerexception @ com.polisee.ballotmeasures.ballotmeasuresfragment$1.onitemselected(ballotmeasuresfragment.java:287) @ android.widget.adapterview.fireonselected(adapterview.java:882) @ android.widget.adapterview.selectionchanged(adapterview.java:865) @ android.widget.adapterview.checkselectionchanged(adapterview.java:1017) @ android.widget.spinner.layout(spinner.java:363) @ android.widget.absspinner.setselectionint(absspinner.java:292) @ android.widget.absspinner.setselection(absspinner.java:269) @ com.polisee.ballotmeasures.ballotmeasuresfragment.setstatespinner(ballotmeasuresfragment.java:314) @ com.polisee.ballotmeasures.ballotmeasuresfragment.oncreateview(ballotmeasuresfragment.java:201) @ android.support.v4.app.fragment.performcreateview(fragment.java:1786) @ android.support.v4.app.fragmentmanagerimpl.movetostate(fragmentmanager.java:953) @ android.support.v4.app.fragmentmanagerimpl.movetostate(fragmentmanager.java:1136) @ android.support.v4.app.backstackrecord.run(backstackrecord.java:739) @ android.support.v4.app.fragmentmanagerimpl.execpendingactions(fragmentmanager.java:1499) @ android.support.v4.app.fragmentmanagerimpl$1.run(fragmentmanager.java:456) @ android.os.handler.handlecallback(handler.java:605) @ android.os.handler.dispatchmessage(handler.java:92) @ android.os.looper.loop(looper.java:137) @ android.app.activitythread.main(activitythread.java:4441) @ java.lang.reflect.method.invokenative(native method) @ java.lang.reflect.method.invoke(method.java:511) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:784) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:551) @ dalvik.system.nativestart.main(native method)

** edit: updated code prevent onitemselected executing twice, needed add null check ballotsdisplay **

@override public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) {     if (savedinstancestate != null) {         log.d("test", "bundle = " + savedinstancestate.tostring());     }      log.d("test", "oncreateview called");      view view = (view) inflater.inflate(r.layout.fragment_ballot_measures, container, false);      setstatespinner(view);      return view; }   private void setstatespinner(view view) {      try {         states = utilities.getallstatenames();     }     catch (exception e) {         log.e("error", "error retrieving names: " + e.getmessage());     }      spinner statespinner = (spinner) view.findviewbyid(r.id.statespinner);      final arrayadapter<string> adapter = new arrayadapter<string>(getactivity(), r.layout.ballotmeasures_state_spinner, states);     adapter.setdropdownviewresource(r.layout.ballotmeasures_state_spinner_dropdown);      statespinner.setadapter(adapter);      statespinner.setonitemselectedlistener(new adapterview.onitemselectedlistener() {          // callback method invoke when state has been selected         public void onitemselected(adapterview<?> parent, view view, int position, long id)         {             log.d("test", "spinner item selected");                  textview stateselected = (textview) view;                 string stateselectedstr = stateselected.gettext().tostring();                  // remove displayed views in layout                 linearlayout ballotsdisplay = (linearlayout) getactivity().findviewbyid(r.id.ballotsdisplay);                 if (ballotsdisplay != null)                 {                     ballotsdisplay.removeallviews();                 }                  map<string, string> calloutparams = new hashmap<string, string>();                 calloutparams.put("state", stateselectedstr);                  // asynctask execute data retrieval                  new retrieveballots().execute(calloutparams);             }          public void onnothingselected(adapterview<?> parent) {             return;         }     });      // set default selection spinner     int defaultstate = adapter.getposition(userstate);      if (defaultstate == -1)     {         defaultstate = 0;     }      log.d("test", "statespinner.setselection");     statespinner.setselection(defaultstate, false); } 

use statespinner.setselection(defaultstate, false); in place of statespinner.setselection(defaultstate);