Android nested ViewPager's fragments dont show after switch between Fragments on Activity -

in application have 1 activity , have fragments , can switch between fragments without problem. 1 of fragments have viewpager other fragments, after switch between parent fragments abd nested fragment viewpager, nested fragments dont show , must close application , run again show that.

main activity:

public void updatefragment(int selecteditem) {     mfragment = null;     fts = getsupportfragmentmanager().begintransaction();     switch (selecteditem) {         case 0:             mfragment = new fragmentmainview();             break;         case 1:             mfragment = new fragmentaddnewwaybill();             break;     }     fts.replace(r.id.mainviewfragments, mfragment, "0");     fts.commit();     mdrawerstate = false; } 

in code can switch between fragments. fragmentmainview() have viewpager defined fragments.

public class fragmentmainview extends fragment {     private fragmentactivity mycontext;     private viewpager vppager;     private fragmentmanager fragmanager;      @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);     }      @override     public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) {         view view = inflater.inflate(r.layout.fragment_main_view, container, false);          g.currentactivity = fragmentmainview.this.getactivity();         fragmanager = mycontext.getsupportfragmentmanager();         vppager = (viewpager) view.findviewbyid(r.id.vppager);         mypageradapter adapterviewpager = new mypageradapter(fragmanager);         vppager.setadapter(adapterviewpager);          return view;     }      public static class mypageradapter extends fragmentpageradapter {         private static int num_items = 2;          public mypageradapter(fragmentmanager fragmentmanager) {             super(fragmentmanager);         }          // returns total number of pages         @override         public int getcount() {             return num_items;         }          // returns fragment display page         @override         public fragment getitem(int position) {             switch (position) {                 case 0:                     return fragmentone.newinstance(0);                 case 1:                     return fragmenttwo.newinstance(1);                 default:                     return null;             }         }          // returns page title top indicator         @override         public charsequence getpagetitle(int position) {             string tabheadertitle = "";             switch (position) {                 case 0:                     tabheadertitle = uc.getstring(r.string.waybill_register_package_owner);                     break;                 case 1:                     tabheadertitle = uc.getstring(r.string.create_new_waybill);                     break;             }             return tabheadertitle;         }     }     @override     public void onattach(activity activity) {         mycontext=(fragmentactivity) activity;         super.onattach(activity);     }      @override     public void onresume() {         super.onresume();     } } 

in first switch on fragmentmainview() in mainactivity fragments on fragmentmainview() viewpager work correctly , show, after switch on fragmentaddnewwaybill() in mainactivity , switch again fragmentmainview() fragments on viewpager dont show , must close application , switch again show that. whats problem?

you have use getchildfragmentmanager() instead of mycontext.getsupportfragmentmanager() when using nested fragments.