fragmenttransaction

I just went through the documentation of the attach() and detach() methods of FragmentTransaction : attach() : Re-attach a fragment after it had previously been detached from the UI with detach(Fragment) . This causes its view hierarchy to be re-created, attached to the UI, and displayed. Well, what does that mean? More specifically, I saw an example: mMapFragment = new MapFragment(); ft.beginTransaction(mMapFragment) .attach() .add(R.id.container, mMapFragment) .commit(); I deleted the attach() and tried again: I did not notice any difference. What does the attach do in this example? What is

My Android app consists three fragments: A, B and C . They're loaded in the two containers defined in the MainActivity layout. When the app is started, it shows the fragmentA loaded in the left_container and the fragmentC in the right_container . If you press the button in the fragmentA , a FragmentTransaction changes FragmentC by FragmentB . At the moment everything OK. But the trouble appears when I try to get a reference to the loaded fragmentB using findFragmentByTag() , because it returns null . I've used the method replace in the FragmentTransaction and I've finished it with commit() ,