java - Viewpager setCurrentItem() doesn't update onPageSelected() -

when swipe between questions, loads current page number correctly

but when use next button, first click doesnt loads pagenumber ( mean onpageselected() doesnt work.) second , other clicks loads content loads 1 page previous.

@override protected void oncreate(final bundle savedinstancestate) {     super.oncreate(savedinstancestate);      this.setcontentview(r.layout.activity_main);      mpager = (viewpager)findviewbyid(r.id.pager);     questionpageradapter madapter = new questionpageradapter();      mpager.setadapter(madapter);      onpagechangelistener pagechangelistener = new onpagechangelistener() {          @override         public void onpagescrollstatechanged(int arg0) { }          @override         public void onpagescrolled(int arg0, float arg1, int arg2) { }          @override         public void onpageselected(int position) {             tv.settext( mpager.getcurrentitem()+"");         }      };      mpager.setonpagechangelistener(pagechangelistener);      question.next.setonclicklistener(new onclicklistener() {          @override         public void onclick(view view) {          mpager.setcurrentitem(getitem(+1));         }     }      private int getitem(int i) {         int = mpager.getcurrentitem();         += a;         return i;     } }); 

why not doing in listener:

mpager.setcurrentitem(mpager.getcurrentitem() + 1);