java - IndexOutOfBoundsException in RecyclerAdapter with Multiple View Types -

i'm getting indexoutofboundsexception when attempting return view type function of position of data in array. have 2 sources of data. 1 advertisement, , other list of names , locations. need combine arrays 1 single array before processing in recycleradapter? i'd rather not, if in principle different types, i.e. images versus text. getitemcount() method returns summed size of 2 arrays. why getting exception? how can achieve desired result of showing data 2 different sources in 2 different view types?

my main activity:

public class mainactivity extends appcompatactivity {      private arraylist<object> getpresidentsarraylist() {         arraylist<object> items = new arraylist<>();         items.add(new president("george washington", "mount vernon"));         items.add(new president("john adams", "braintree"));         items.add(new president("thomas jefferson", "monticello"));         items.add(new president("james madison", "port conway"));         return items;     }      private arraylist<object> getadsarraylist() {         arraylist<object> ads = new arraylist<>();         ads.add(new sponsored("craft beer 20% off", "budweiser"));         ads.add(new sponsored("craft beer 20% off", "budweiser"));         ads.add(new sponsored("craft beer 20% off", "budweiser"));         ads.add(new sponsored("craft beer 20% off", "budweiser"));         return ads;     }      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);          recyclerview recyclerview = (recyclerview) findviewbyid(r.id.recyclerview);         recyclerview.setlayoutmanager(new linearlayoutmanager(this));         binddatatoadapter(recyclerview);      }      private void binddatatoadapter(recyclerview recyclerview) {         recyclerview.setadapter(new heterogeneousrecycleradapter(getpresidentsarraylist(), getadsarraylist()));     }  } 

my recycler adapter allowing multiple views:

public class heterogeneousrecycleradapter extends recyclerview.adapter<recyclerview.viewholder> {      private list<object> items;     private list<object> ads;     private final int president = 0, sponsored = 1;      public heterogeneousrecycleradapter(list<object> items, list<object> ads) {         this.items = items;         this.ads = ads;     }      @override     public int getitemcount() {         return (this.items.size() + this.ads.size());     }      @override     public int getitemviewtype(int position) {         if (items.get(position) instanceof president) {             return president;         } else if (ads.get(position) instanceof sponsored) {             return sponsored;         }         return -1;     }      @override     public recyclerview.viewholder oncreateviewholder(viewgroup viewgroup, int viewtype) {          recyclerview.viewholder viewholder;         layoutinflater inflater = layoutinflater.from(viewgroup.getcontext());          switch (viewtype) {             case president:                 view v1 = inflater.inflate(r.layout.layout_viewholder1, viewgroup, false);                 viewholder = new viewholder1(v1);                 break;             case sponsored:                 view v2 = inflater.inflate(r.layout.layout_viewholder2, viewgroup, false);                 viewholder = new viewholder2(v2);                 break;             default:                 view v = inflater.inflate(android.r.layout.simple_list_item_1, viewgroup, false);                 viewholder = new recyclerviewsimpletextviewholder(v);                 break;         }         return viewholder;     }      @override     public void onbindviewholder(recyclerview.viewholder viewholder, int position) {         switch (viewholder.getitemviewtype()) {             case president:                 viewholder1 vh1 = (viewholder1) viewholder;                 configureviewholder1(vh1, position);                 break;             case sponsored:                 viewholder2 vh2 = (viewholder2) viewholder;                 configureviewholder2(vh2, position);                 break;             default:                 recyclerviewsimpletextviewholder vh = (recyclerviewsimpletextviewholder) viewholder;                 configuredefaultviewholder(vh, position);                 break;         }     }      private void configuredefaultviewholder(recyclerviewsimpletextviewholder vh, int position) {         vh.getlabel().settext((charsequence) items.get(position));     }      private void configureviewholder1(viewholder1 vh1, int position) {         president president = (president) items.get(position);         if (president != null) {             vh1.getlabel1().settext(president.getname());             vh1.getlabel2().settext(president.gethometown());         }     }      private void configureviewholder2(viewholder2 vh2, int position) {         sponsored sponsored = (sponsored) ads.get(position);         if (sponsored != null) {             vh2.getlabel1().settext(sponsored.getname());             vh2.getlabel2().settext(sponsored.getcompany());         }     } } 

you need create common list adding both list. following -

    public heterogeneousrecycleradapter(list<object> items, list<object> ads) {         this.items = items;         items.addall(ads);     } 

now change item count -

@override public int getitemcount() {     return this.items.size(); } 

hope work fine :)