android - Calling a fragment from another fragment on click -

what want call 1 fragment on click on item of listview. program builds without errors crash on click on item. btw i’m making here local fragment_3 object, have got done in mainactivity, how pass function?

fragment_1.java content:

public class fragment_1 extends sherlockfragment implements onitemclicklistener{   @override  public view oncreateview(layoutinflater inflater, viewgroup container,             bundle savedinstancestate) {      super.oncreate(savedinstancestate);    // requestwindowfeature(window.feature_no_title);     view view = inflater.inflate(r.layout.fragment_1, container, false);     listview listview = (listview) view.findviewbyid(r.id.listview1);     listview.setonitemclicklistener(this);       return view; } @override public void onitemclick(adapterview<?> parent, view v, int position, long id) {     // todo auto-generated method stub     fragment fragment3 = new fragment_3();     integer fragmentid = (integer) v.gettag();     fragmentmanager fragmentmanager = getfragmentmanager();     fragmenttransaction fragmenttransaction = fragmentmanager.begintransaction();     fragmenttransaction.replace(fragmentid, fragment3);     fragmenttransaction.commit();  }  } 

my suspicion v.gettag() null; integer fragmentid = (integer) v.gettag(); end in fragmentid being null. when unboxing int you'll nullpointerexception. why don't replace fragmentid in fragmenttransaction.replace(fragmentid, fragment3); id of container holds current instance of fragment_1?