Listadapter duplicating items in listview after each time asynctask starts

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http://stackoverflow.com – I have a listview in fragment. It loads data from Json. After clicking list items a fragment transaction begins (replace). By pressing back button (in new fragment) again list fragment appears but the problem is that: 1: It loads again Asynctask (that I don't want it). 2. It adds new items on top of the former items in the list. You can say duplication in listview items happens. Each time I click listview item abd then return back to listview fragment it adds the same items to the end of the list. My code is this: public class Followed extends Fragment { public Followed(){} ArrayList< (HowTos)