android - Getview parameter "convertview" not null on new "position" parameter -

i'm using arrayadapter list of own type of objects (only 1 type) , give user option create more items (thus creating more views items). @ point, getview sent new "position" index non-null "convertview". shows first view in last position. after that, when scrolling views mixed up. i'm assuming means manipulated views in ways shouldn't have don't see where. here code:

    @override public view getview(int position, view convertview, viewgroup parent) {     view v;     previewitemholder holder = null;      // initialize view if convertview null     if (convertview == null) {         v = newview(parent, position);     }     // populate saved holder     else {         // use previous item if not null         v = convertview;     }      // populate if holder null (newly inflated view) or     // if current view's holder's flag true , requires populating     if ((holder == null) || (holder.readpopulateflag())) {         bindview(position, v);     }      return v; }      private view newview(viewgroup parent, int position) {     // getting view somehow...     layoutinflater inflater = (layoutinflater) getcontext().getsystemservice(context.layout_inflater_service);     view inflatedview = inflater.inflate(r.layout.preview_element_set, parent, false);     previewitemholder holder = new previewitemholder();      holder.set = (set) msets.get(position);     holder.previewelementholders = new arraylist<previewelementholder>();     holder.expandarea = (view) inflatedview.findviewbyid(r.id.expandarea);     holder.repetitionslabel = (textview) inflatedview.findviewbyid(r.id.previewrepetitionsinput);     holder.endlessinput = (checkbox) inflatedview.findviewbyid(r.id.previewsetendlessinput);     holder.namelabel = (textview) inflatedview.findviewbyid(r.id.previewsetnamelabel);     holder.commentinput = (edittext) inflatedview.findviewbyid(r.id.previewsetcommentinput);     holder.soundinput = (edittext) inflatedview.findviewbyid(r.id.previewsetsoundinput);     holder.addelementbutton = (button) inflatedview.findviewbyid(r.id.previewsetaddelements);     holder.expand = (view) inflatedview.findviewbyid(r.id.infoarea);     holder.collapse = (view) inflatedview.findviewbyid(r.id.collapse);      final int setslength = holder.set.getelements().size();      (int = 0; < setslength; i++) {         aelement currelement = holder.set.getelements().get(i);          // creating new element holder according type         if (currelement instanceof rest) {             holder.previewelementholders.add(new previewrestholder());         }         else if (currelement instanceof timeexercise) {             holder.previewelementholders.add(new previewtimeexerciseholder());         }         else if (currelement instanceof repetitionexercise) {             holder.previewelementholders.add(new previewrepetitionexerciseholder());         }          view currlayout = inflateelement(currelement, inflater, i, holder.previewelementholders.get(i));          // add child before hairline, collapse image , add         // button         // (3 last children of expandarea view         ((viewgroup) holder.expandarea).addview(currlayout, ((viewgroup) holder.expandarea).getchildcount() - children_index_after_phases_label);     }      inflatedview.settag(holder);      return inflatedview; }  private void bindview(int position, view inflatedview) {     final previewitemholder holder = (previewitemholder) inflatedview.gettag();     holder.set.setid(position);     holder.endlessinput.setchecked(holder.set.getendless());     holder.soundinput.settext(holder.set.getsound());     holder.namelabel.settext(holder.set.getname());     holder.commentinput.settext(holder.set.getcomment());      // make sure there name. if none, put default     if (holder.namelabel.gettext().equals("")) {         holder.namelabel.settext(r.string.default_set_name);     }      // set repetitions value according endless flag     if (holder.set.getendless()) {         holder.repetitionslabel.settext(r.string.infinity);     }     else {         holder.repetitionslabel.settext(string.valueof(holder.set.getrepetitions()));     }      // set click listeners     holder.endlessinput.setoncheckedchangelistener(new oncheckedchangelistener() {          @override         public void oncheckedchanged(compoundbutton buttonview, boolean ischecked) {              // save endless flag             holder.set.setendless(ischecked);              // if endless set - dropset             if (ischecked) {                 holder.repetitionslabel.settext(r.string.infinity);             }             else {                 // regular set                 holder.repetitionslabel.settext(string.valueof(holder.set.getrepetitions()));             }              hideshowrepsweights(holder);         }      });      holder.repetitionslabel.setonclicklistener(new onclicklistener() {         @override         public void onclick(view v) {              numericdialog instance = numericdialog.newinstance(holder, holder.set, numericdialog.integer_mode, consts.set_repetitions_method_name);             instance.show(((activity) getcontext()).getfragmentmanager(), null);         }     });      holder.namelabel.setonclicklistener(new onclicklistener() {         @override         public void onclick(view v) {             // setting flag true allow populating view             holder.repopulateflag = true;             setnamedialog instance = setnamedialog.newinstance(holder.set);             instance.show(((activity) getcontext()).getfragmentmanager(), null);         }     });      holder.commentinput.setonfocuschangelistener(new onfocuschangelistener() {         @override         public void onfocuschange(view v, boolean hasfocus) {             if (!hasfocus) {                 // after focus lost, save text set                 holder.set.setcomment(holder.commentinput.gettext().tostring());             }         }     });      // todo change dialog allows selection of sounds     holder.soundinput.setonfocuschangelistener(new onfocuschangelistener() {         @override         public void onfocuschange(view v, boolean hasfocus) {             if (!hasfocus) {                 // after focus lost, save text set                 holder.set.setsound(holder.soundinput.gettext().tostring());             }         }     });      holder.expand.setonclicklistener(new onclicklistener() {         @override         public void onclick(view v) {             // change visibility - show expandarea , data             holder.expandarea.setvisibility(view.visible);             holder.expand.setvisibility(view.gone);             holder.collapse.setvisibility(view.visible);         }     });      holder.collapse.setonclicklistener(new onclicklistener() {         @override         public void onclick(view v) {             // change visibility - hide expandarea , data             holder.expandarea.setvisibility(view.gone);             holder.collapse.setvisibility(view.gone);             holder.expand.setvisibility(view.visible);         }     });      holder.addelementbutton.setonclicklistener(new onclicklistener() {         @override         public void onclick(view v) {             addelementdialog instance = addelementdialog.newinstance(holder);             instance.show(((activity) getcontext()).getfragmentmanager(), null);         }     });      // populate elements     (previewelementholder elementholder : holder.previewelementholders) {         populateelement(elementholder, holder);     }      // hide/show if needed - should put somewere else?     hideshowrepsweights(holder); } 

please tell me if think should upload more methods make things clearer.

a friend explained problem me , seems work. listview holds small number of views , recycles them time. in case have nexus 4 , seems have 7 views total because 8th 1 started cause trouble. missing in getview() condition checking correlation between position , id of current item within arrayadapter. here how looks works:

@override public view getview(int position, view convertview, viewgroup parent) {     view v;     previewitemholder holder = null;      // initialize view if convertview null     if (convertview == null) {         v = newview(parent, position);     }     // populate saved holder     else {         // if position , id of set not match, view needs re-created, not recycled         if (((previewitemholder) convertview.gettag()).set.getid() != position) {             v = newview(parent, position);         }         else {             // use previous item if not null             v = convertview;              // holder             holder = (previewitemholder) v.gettag();         }     }      // populate if holder null (newly inflated view) or     // if current view's holder's flag true , requires populating      if ((holder == null) || (holder.readpopulateflag())) {     bindview(position, v);      }      return v; }