Activity and Fragment Lifecycles and Orientation Changes

Question

I have been having very odd issues with Fragments and orientation changes that have been causing force closes and not following a logical pattern.

I created

Answer 1

It is because you are adding the fragment again and again in activity is recreated. You can use the below code in activity's onCreate method to avoid recreation of fragment:

if(savedInstanceState == null) 
{
    mFragmentManager = getSupportFragmentManager();
    FragmentTransaction fragmentTransaction = mFragmentManager.beginTransaction();

    FragmentOne fragment = new FragmentOne();

    fragmentTransaction.add(R.id.fragment_container, fragment);
    fragmentTransaction.commit();
}

When a config change occurs the old Fragment isn't destroyed -- it adds itself back to the Activity when it's recreated.

Answer 2

This happens because the activity calls onSaveInstanceState(Bundle) before being destroyed. By default, the activity is saving the states of its fragments in this method.

Later, when the activity is re-created, the old fragments are re-created in the activity onCreate(Bundle savedInstanceState) method.

You might want to check the source code here and here to better understand this behaviour.