java - Replacing Main Fragment from its Child Fragment -

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i'm trying replace mainfragment other fragment childfragment of mainfragment. using part of code:

 android.support.v4.app.fragmentmanager fragmentmanager = getfragmentmanager();                     fragment fragment = null;                     fragment = mainfragment2.class.newinstance();                     fragmentmanager.begintransaction().replace(r.id.flcontent, fragment).commit();                     fragmentmanager.executependingtransactions(); 

problem is, mainfragment get's destroyed , replacing successful, problem child of mainfragment never gets destroyed , child methods(destroy, pause, stop..) never called(i need methods). remain in memory , when getting between activities in app onresume() method of child fragment gets called. strange. i'm doing wrong here?

create interface :

interface mainnavigaton {       void replacefragment();  } 

on main activity

class activity exteds... implements mainnavigation       public void replacefragment() {           //replace fragment here.       } 

all childs used activity :

  private mainnavigation mainnav;   public void onattach(context context) {         mainnav = (mainnavigation) context;    } 

replace fragment want.

action.onclicklistner(new view.onclicklistneer() {         mainnav.replacefragment();     }