android - BaseAdapter.notifyDataSetChanged inverts order of elements -

for navigation in android app using listview , create , set baseadapter in oncreate method of activity.

the baseadapter accesses arraylist retrieve elements (cache.getnavigation()):

public class navigationadapter extends baseadapter {     context mcontext;      public navigationadapter(context c) {         mcontext = c;     }      @override     public int getcount() {         return cache.getnavigation() != null ? cache.getnavigation().size()                 : 0;     }      @override     public object getitem(int position) {         return cache.getnavigation() != null ? cache.getnavigation().get(                 position) : 0;     }      @override     public long getitemid(int position) {         return cache.getnavigation() != null ? cache.getnavigation().get(                 position).getid() : 0;     }      @override     public view getview(int position, view convertview, viewgroup parent) {         view v;         if (convertview == null) {             layoutinflater li = getlayoutinflater();                  v = li.inflate(r.layout.list_nav_icon, null);                 textview tv = (textview) v.findviewbyid(r.id.list_nav_text);                 tv.settext(((templateinstancedto) getitem(position))                         .getname());                  imageview icon = (imageview) v                         .findviewbyid(r.id.list_nav_icon);                 byte[] binary = ((templateinstancedto) getitem(position))                         .geticon();                 bitmap bm = bitmapfactory.decodebytearray(binary, 0,                         binary.length);                 icon.setimagebitmap(bm);                  imageview arrow = (imageview) v                         .findviewbyid(r.id.list_nav_arrow);                 arrow.setimageresource(r.drawable.arrow);           } else {             v = convertview;         }         return v;     } } 

so navigation built on startup cache. meanwhile start asynctask retrieves navigation arraylist server , when has changed saves new navigation cache:

private class remotetask extends         asynctask<long, integer, list<templateinstancedto>> {     protected list<templateinstancedto> doinbackground(long... ids) {         try {             remotetemplateinstanceservice service = (remotetemplateinstanceservice) servicefactory                     .getservice(remotetemplateinstanceservice.class,                             getclassloader());              list<templateinstancedto> templates = service                     .findbyaccountid(ids[0]);              return templates;         } catch (exception e) {             return null;         }     }      protected void onpostexecute(list<templateinstancedto> result) {         if (result != null && result.size() > 0) {             cache.savenavigation(result);             populatedata();         } else {             toast text = toast.maketext(listnavigationactivity.this,                     "server communication failed.", 3);             text.show();         }     } } 

when nothing more in populatedata(), listview doesn´t update. when call ((baseadapter) listview.getadapter()).notifydatasetchanged() view updated, order inverted. first item last , last first , on.

held needed! in advance.

the problem lies getview() function. through different calls of method, view objects cached, though not coupled position.

with proper logs, can see behavior as:

 pos1: view1   pos2: view2  pos3: view3  pos3: view1  pos2: view2  pos1: view3 

thats why list getting inverted. solution: on each call of getview, set values in value if object exists. i.e.:

 public view getview(int position, view convertview, viewgroup parent) {     view v;     if (convertview == null) {         layoutinflater li = getlayoutinflater();         v = li.inflate(r.layout.list_nav_icon, null);     } else {         v = convertview;     }     textview tv = (textview) v.findviewbyid(r.id.list_nav_text);     tv.settext(((templateinstancedto) getitem(position))                     .getname());      imageview icon = (imageview) v                     .findviewbyid(r.id.list_nav_icon);     byte[] binary = ((templateinstancedto) getitem(position))                     .geticon();     bitmap bm = bitmapfactory.decodebytearray(binary, 0,                     binary.length);     icon.setimagebitmap(bm);      imageview arrow = (imageview) v                     .findviewbyid(r.id.list_nav_arrow);     arrow.setimageresource(r.drawable.arrow);      return v; }