How setRetainInstance(true) affect lifecycle of Fragment

It's part of the articles of lifecycle: start reading from Understand lifecycle of Activity and Fragment, Introduction.

The Fragment.setRetainInstance() method control whether a fragment instance is retained across Activity re-creation (such as from a configuration change). This can only be used with fragments not in the back stack. If set, the fragment lifecycle will be slightly different when an activity is recreated:
  • onDestroy() will not be called (but onDetach() still will be, because the fragment is being detached from its current activity).
  • onCreate(Bundle) will not be called since the fragment is not being re-created.
  • onAttach(Activity) and onActivityCreated(Bundle) will still be called.
~ reference: http://developer.android.com/reference/android/app/Fragment.html#setRetainInstance(boolean)

Refer to the last exercise, "UI elements lost after Activity/Fragment re-created". Consider the image_c, it is loaded in onCreateView(), only if savedInstanceState == null. Without setRetainInstance(true), it will not be loaded after orientation changed, because savedInstanceState != null.

image_c lost after orientation changed, without setRetainInstance(true)


MYTAG LogCat listed here:

Orientation changed:
  • MainActivity.onPause
  • MyFragment1.onPause
  • MainActivity.onStop
  • MyFragment1.onStop
  • MainActivity.onDestroy
  • MyFragment1.onDestroyView
  • MyFragment1.onDestroy
  • MyFragment1.onDetach
  • MainActivity.onCreate / savedInstanceState != null
  • MyFragment1.onAttach
  • MyFragment1.onCreate / savedInstanceState != null
  • MainActivity.onStart
  • MyFragment1.onCreateView / savedInstanceState != null
  • MyFragment1.onActivityCreated / savedInstanceState != null
  • MyFragment1.onStart
  • MainActivity.onResume
  • MyFragment1.onResume


To know how setRetainInstance(true) affect lifecycle of Fragment, modify MyFragment.java from last exercise "UI elements lost after Activity/Fragment re-created", override onActivityCreated() method to call setRetainInstance(true).

 @Override
 public void onActivityCreated(Bundle savedInstanceState) {
  recLifeCycle_with_savedInstanceState(savedInstanceState);
  super.onActivityCreated(savedInstanceState);
  
  setRetainInstance(true);
 }

image_c reloaded after orientation changed, with setRetainInstance(true).

LogCat in Orientation Changed:
  • MainActivity.onPause
  • MyFragment1.onPause
  • MainActivity.onStop
  • MyFragment1.onStop
  • MainActivity.onDestroy
  • MyFragment1.onDestroyView
  • MyFragment1.onDetach
  • MainActivity.onCreate / savedInstanceState != null
  • MyFragment1.onAttach
  • MainActivity.onStart
  • MyFragment1.onCreateView / savedInstanceState == null
  • MyFragment1.onActivityCreated / savedInstanceState == null
  • MyFragment1.onStart
  • MainActivity.onResume
  • MyFragment1.onResume



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* the original chart of fragment lifecycle is taken here.