java - Null object reference when initializing spinners in tablayout -

i have multiple tabs spinners in them, , when switch fragment sliders need initialized corresponding string-arrays. issue keep receiving "null object reference" error. here's code.

fragment code:

public class pageone extends fragment {     public static final string arg_page = "arg_page";      private int mpage;      public static pageone newinstance(int page) {         bundle args = new bundle();         args.putint(arg_page, page);         pageone fragment = new pageone();         fragment.setarguments(args);         return fragment;     }     @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         mpage = getarguments().getint(arg_page);     }      @override     public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) {         mainactivity mainactivity = new mainactivity();         if(mpage>=3) {             mainactivity.addshittospinners(mpage);         }         view view = inflater.inflate(r.layout.fragment_page_one, container, false);         //tips         if(mpage == 1) {             view = inflater.inflate(r.layout.fragment_page_one, container, false);             return view;         }         //main         if(mpage == 2) {             view = inflater.inflate(r.layout.page_two, container, false);             return view;         }         //auto         if(mpage == 3) {             view = inflater.inflate(r.layout.page_three, container, false);             return view;         }         //defenses         if(mpage == 4) {             view = inflater.inflate(r.layout.page_four, container, false);             return view;         }         //shooting         if(mpage == 5) {             view = inflater.inflate(r.layout.page_five, container, false);             return view;         }         //end game         if(mpage == 6) {             view = inflater.inflate(r.layout.page_six, container, false);             return view;         }         return view;     } } 

heres code mainactivity (where spinners initialized):

public class mainactivity extends appcompatactivity {

@override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);     toolbar mytoolbar = (toolbar) findviewbyid(r.id.main_toolbar);     setsupportactionbar(mytoolbar);     tablayout tablayout = (tablayout)findviewbyid(r.id.tabs);     viewpager viewpager = (viewpager)findviewbyid(r.id.view_p);     viewpager.setadapter(new myfragmentpageradapter(getsupportfragmentmanager(), mainactivity.this));     tablayout.setupwithviewpager(viewpager); }   @override public boolean oncreateoptionsmenu(menu menu) {     // inflate menu; adds items action bar if present.     getmenuinflater().inflate(r.menu.menu_main, menu);     return true; }  @override public boolean onoptionsitemselected(menuitem item) {     // handle action bar item clicks here. action bar     // automatically handle clicks on home/up button, long     // specify parent activity in androidmanifest.xml.     int id = item.getitemid();      //noinspection simplifiableifstatement     if (id == r.id.action_settings) {         return true;     }      return super.onoptionsitemselected(item); }  public void addshittospinners(int i) {     system.out.print(i);     if(i==3) {         spinner startingzone = (spinner) findviewbyid(r.id.auto_start_spinner);         arrayadapter<charsequence> adapterstart = arrayadapter.createfromresource(this,                 r.array.zones, android.r.layout.simple_spinner_item);         adapterstart.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item);         startingzone.setadapter(adapterstart);          spinner crossorreachspinner = (spinner) findviewbyid(r.id.cross_or_reach_spinner);         arrayadapter<charsequence> adaptercr = arrayadapter.createfromresource(this,                 r.array.cross_or_reach, android.r.layout.simple_spinner_item);         adaptercr.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item);         crossorreachspinner.setadapter(adaptercr);          spinner autodcrossed = (spinner) findviewbyid(r.id.auto_defense_spinner);         arrayadapter<charsequence> adapterautodcrossed = arrayadapter.createfromresource(this,                 r.array.defenses, android.r.layout.simple_spinner_item);         adapterautodcrossed.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item);         autodcrossed.setadapter(adapterautodcrossed);          spinner autohimade = (spinner) findviewbyid(r.id.hi_made_auto_spinner);         arrayadapter<charsequence> adapterhimade = arrayadapter.createfromresource(this,                 r.array.shots, android.r.layout.simple_spinner_item);         adapterhimade.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item);         autohimade.setadapter(adapterhimade);          spinner autolomade = (spinner) findviewbyid(r.id.lo_made_auto_spinner);         arrayadapter<charsequence> adapterlo = arrayadapter.createfromresource(this,                 r.array.shots, android.r.layout.simple_spinner_item);         adapterlo.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item);         autolomade.setadapter(adapterlo);     }      if(i==4) {         arrayadapter<charsequence> adaptercrosses = arrayadapter.createfromresource(this,                 r.array.crosses, android.r.layout.simple_spinner_item);         adaptercrosses.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item);          spinner portculliscrosses = (spinner) findviewbyid(r.id.portcullis_spinner);         spinner chevalcrosses = (spinner) findviewbyid(r.id.cheval_spinner);         spinner rampartscrosses = (spinner) findviewbyid(r.id.ramparts_spinner);         spinner moatcrosses = (spinner) findviewbyid(r.id.moat_spinner);         spinner drawcrosses = (spinner) findviewbyid(r.id.draw_bridge_spinner);         spinner sallycrosses = (spinner) findviewbyid(r.id.sally_port_spinner);         spinner rockwallcrosses = (spinner) findviewbyid(r.id.rockwal_spinner);         spinner roughcrosses = (spinner) findviewbyid(r.id.rough_terrain_spinner);         spinner lowcrosses = (spinner) findviewbyid(r.id.low_bar_spinner);          portculliscrosses.setadapter(adaptercrosses);         chevalcrosses.setadapter(adaptercrosses);         rampartscrosses.setadapter(adaptercrosses);         moatcrosses.setadapter(adaptercrosses);         drawcrosses.setadapter(adaptercrosses);         sallycrosses.setadapter(adaptercrosses);         rockwallcrosses.setadapter(adaptercrosses);         roughcrosses.setadapter(adaptercrosses);         lowcrosses.setadapter(adaptercrosses);     }      if(i==5) {         arrayadapter<charsequence> adaptershots = arrayadapter.createfromresource(this,                 r.array.shots, android.r.layout.simple_spinner_item);         adaptershots.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item);          spinner himade = (spinner) findviewbyid(r.id.hi_made_spinner);         spinner hifail = (spinner) findviewbyid(r.id.hi_failed_spinner);         spinner lomade = (spinner) findviewbyid(r.id.lo_made_spinner);          himade.setadapter(adaptershots);         hifail.setadapter(adaptershots);         lomade.setadapter(adaptershots);     }      if(i==6) {         spinner scale = (spinner) findviewbyid(r.id.scale_spinner);         spinner capture = (spinner) findviewbyid(r.id.capture_spinner);          arrayadapter<charsequence> adapteryorn = arrayadapter.createfromresource(this,                 r.array.y_or_n, android.r.layout.simple_spinner_item);         adapteryorn.setdropdownviewresource(android.r.layout.simple_spinner_dropdown_item);          scale.setadapter(adapteryorn);         capture.setadapter(adapteryorn);     } } 

}

instead of:

mainactivity mainactivity = new mainactivity(); if(mpage>=3) {     mainactivity.addshittospinners(mpage); } 

use:

if(mpage>=3) {     ((mainactivity) getactivity()).addshittospinners(mpage); }