java - Interface value is always null -

i using custom recycler view , in adapter class have implemented interface null on button click. here adapter class.

public class feedlistadapter extends     recyclerview.adapter<addtocartholder> {   private onfeeditemclicklistener onfeeditemclicklistener;  public feedlistadapter(activity activity, arraylist<cartitem> feeditems) {     this.activity = activity;     this.feeditems = feeditems;     this.filteredfeeditems = feeditems;      inflater = layoutinflater.from(activity); }   public void setonfeeditemclicklistener(onfeeditemclicklistener onfeeditemclicklistener) {         this.onfeeditemclicklistener = onfeeditemclicklistener;     }  @override public addtocartholder oncreateviewholder(viewgroup parent, int viewtype) {     view v = layoutinflater.from(parent.getcontext()).inflate(             r.layout.feed_item, parent, false);     addtocartholder viewholder = new addtocartholder(v);      setupclickableviews(v, viewholder);     return viewholder; } @override public void onbindviewholder(final addtocartholder holder, int position) {      cartitem item = (cartitem) filteredfeeditems.get(position);     holder.price.settext((string.valueof(item.getproductname()) + ""));     holder.location.settext((string.valueof(item.getquantity())) + "");   }  private void setupclickableviews(final view view, final addtocartholder cellfeedviewholder) {      cellfeedviewholder.plus.setonclicklistener(new view.onclicklistener() {             @override             public void onclick(view v) {                 if(onfeeditemclicklistener !=null){                 onfeeditemclicklistener.onaddclick(v, cellfeedviewholder.getadapterposition());                 }                 else{                     toast.maketext(activity, "data null", toast.length_long).show();                 }             }         }); }   public interface onfeeditemclicklistener {         void onaddclick(view v, int position);      }  @override public int getitemcount() {     return filteredfeeditems.size(); } 

i getting null whenever clicking on button down know why coming null...

here fragment class have implemented interface.

public class myfragment extends fragment implements feedlistadapter.onfeeditemclicklistener{  // method @override public void onaddclick(view v, int position) {     // todo auto-generated method stub     snackbar.make(clcontent, "product removed cart!",             snackbar.length_short).show(); } 

you must instantiating feedlistadapter in fragment correct buddy ???

like using statement :

feedlistadapter adapter = new feedlistadapter(this.getactivity(),your_array_list) 

after instantiating adapter call adapter's setonfeeditemclicklistener 'this' argument :) that's :)

adapter.setonfeeditemclicklistener(this) 

hope answer helped :) happy coding buddy :)