android - Issue on update data by notifyDataSetChanged in RecyclerView -

i used recycler view show list of data. called web service , data server , update current arraylist server data. how fill data in current arraylist.

maluotesdatas.clear(); maluotesdatas = (arraylist<billboarddata>) webservice.data; muotesadaptor.notifydatasetchanged(); 

and apply notifydatasetchanged() reflect in list of data doesn't reflect list. in maluotesdatas shows updated data doesn't shows updated list of data.

after change

maluotesdatas.clear(); maluotesdatas.addall(res.data); muotesadaptor.notifydatasetchanged(); 

this works fine. surprising me, how works??, though both have updated data after web service call.

can me understand how can be.?

this class.

package com.mimran.aphorismus.models;  import android.os.bundle; import android.support.v7.widget.recyclerview; import android.view.layoutinflater; import android.view.view; import android.view.viewgroup;  import com.mimran.aphorismus.r; import com.mimran.aphorismus.adapters.quotesadaptor;  import java.util.arraylist;  public class datafragment extends fragment {  private recyclerview mrcvquotes; private quotesadaptor muotesadaptor; private arraylist<billboarddata> maluotesdatas;   @override public view oncreateview(layoutinflater inflater, viewgroup container,                          bundle savedinstancestate) {      mrcvquotes = (recyclerview) links(r.id.rcv_quotes);     muotesadaptor = new quotesadaptor(mcontext, maluotesdatas);     mrcvquotes.setadapter(muotesadaptor);      return inflater.inflate(r.layout.my_view, container, false); }  public void webservicecall() {     public void onresponse ()     {         if (response.issuccess()) {             maluotesdatas.clear();             //maluotesdatas = (arraylist<billboarddata>) res.data;             maluotesdatas.addall(res.data);             muotesadaptor.notifydatasetchanged();         }     }  } } 

it doesn't work because don't add items proper instance of data collection.

adapter initialized in constructor specific instance of data collection , it's working on time.

after this:

 maluotesdatas = (arraylist<billboarddata>) webservice.data; 

maluotesdatas reference different collection adapter's instance.

then:

muotesadaptor.notifydatasetchanged(); 

actually notify adapter changes in "old" data collection hasn't changed.

when use clear , addall works because work same instance , you're replacing items inside it.