android - OnLongClickListener() not firing up in adapter class -

in android pageradapter class have defined onlongclicklistener. not working while running. couldn't find problem here, appreciated

code

public class fullscreenimageadapter extends pageradapter {      private activity _activity;     private arraylist<string> _imagepaths;     private layoutinflater inflater;      // constructor     public fullscreenimageadapter(activity activity,             arraylist<string> imagepaths) {         this._activity = activity;         this._imagepaths = imagepaths;     }      @override     public int getcount() {         return this._imagepaths.size();     }      @override     public boolean isviewfromobject(view view, object object) {         return view == ((relativelayout) object);     }      @override     public object instantiateitem(viewgroup container, int position) {         touchimageview imgdisplay;         button btnclose;          inflater = (layoutinflater) _activity                 .getsystemservice(context.layout_inflater_service);         view viewlayout = inflater.inflate(r.layout.layout_fullscreen_image, container,                 false);          imgdisplay = (touchimageview) viewlayout.findviewbyid(r.id.imgdisplay);         btnclose = (button) viewlayout.findviewbyid(r.id.btnclose);          imgdisplay.setonlongclicklistener(new view.onlongclicklistener() {              @override             public boolean onlongclick(view v) {                 // todo auto-generated method stub                 system.exit(0);                 return true;             }         });         imageloader2 imageloader = new imageloader2(_activity);                imageloader.displayimage(_imagepaths.get(position), imgdisplay);          // close button click event         btnclose.setonclicklistener(new view.onclicklistener() {                         @override             public void onclick(view v) {                 _activity.finish();             }         });           ((viewpager) container).addview(viewlayout);          return viewlayout;     }      @override     public void destroyitem(viewgroup container, int position, object object) {         ((viewpager) container).removeview((relativelayout) object);      }   }