expandablelistview - Android : what happens when I re-launch my app after a long break -

i'm developing app main activity 3 tab actionbar. 1 of tabs handles expandablelistview want indicator stay on right, in mainactivity got :

public void onwindowfocuschanged(boolean hasfocus) {     super.onwindowfocuschanged(hasfocus);     if (tab != null){         lv.setindicatorrightfunction(); //sets indicator on right side     } } 

my problem sometimes, function not called , indicator remains left! added setindicatorrightfunction() in onresume() , seemed work fine when app onpause().

the problem when go afk while, or switches on multiple other apps on phone. then, when relaunch app, indicator appears on left side ! setindicatorrightfunction() not called! there method can call solve problem ? doing wrong ?

edit :

i figured out function wasn't called because tab equals null. why ? how can solve ?

    @override     public fragment getitem(int position) {         // getitem called instantiate fragment given page.         switch (position) {         case 0:             tab = new tabfragment();             return tab;         }     } 

aren't there onresume() functions-like fragments ? solution can see, call setindicator function when fragments resumed/...