android - How can I use pager.setCurrentItem() inside a fragment? -

i created many fragments, fragment1 , fragment2.. , fragment50 inside first fragment listener method want call fragment40. didnt manage. inside listener these lines runs

pager.setcurrentitem(0); pager.setcurrentitem(pager.getcurrentitem() + 1); pager.setcurrentitem(pager.getcurrentitem() - 1); pager.setcurrentitem(40); not run. gives errors. please? //first fragment01 //i want call fragment40 public class frag_2 extends  fragment implements          onclicklistener, adapterview.onitemselectedlistener { //.................................................... public void onactivitycreated(bundle savedinstancestate) {super.onactivitycreated(savedinstancestate); final viewpager pager = (viewpager) getactivity().findviewbyid(r.id.pager); view txtdershakkinda1 = (view) getactivity().findviewbyid(r.id.txtdershakkinda1); txtdershakkinda1.setonclicklistener(new onclicklistener() { @override public void onclick(view v) { pager.setcurrentitem(pager.getcurrentitem()+40);    // not run //  pager.setcurrentitem(0);    //runs //  pager.setcurrentitem(pager.getcurrentitem() + 1); //  pager.setcurrentitem(pager.getcurrentitem() - 1); } } );     //...................................................................... } /////////////////////// if many fragments --> fragmentstatepageradapter ///////////// public class mypageradapter extends fragmentstatepageradapter { private list<fragment> fragments; public mypageradapter(fragmentmanager fm) { super(fm); this.fragments = new arraylist<fragment>(); fragments.add(new frag_1<object>()); fragments.add(new frag_2()); fragments.add(new frag_3()); fragments.add(new frag_4());  ..................... fragments.add(new frag_50()); } @override public fragment getitem(int position) { return fragments.get(position); } @override public int getcount() { return fragments.size(); } } 

add methods adapter :

 @override     public object instantiateitem(viewgroup container, int position) {         fragment fragment = (fragment) super.instantiateitem(container, position);         registeredfragments.put(position, fragment);         return fragment;     }      @override     public void destroyitem(viewgroup container, int position, object object) {         registeredfragments.remove(position);         super.destroyitem(container, position, object);     }      public fragment getregisteredfragment(int position) {         return registeredfragments.get(position);     } 

and cant items this: adapater.getregisteredfragment(viewpager.getcurrentitem())