Android – when replacing a fragment, the savedinstancestate bundle is cleared when restoring the fragment after double rotation

We call them fragments a and B. fragment B is just a detailed view of A. it replaces fragment a when a button is clicked in fragment a

Replacement code:

    FragmentTransaction transaction = getFragmentManager().beginTransaction();
    transaction.replace(R.id.fragment_container, new DetailFragment());
    transaction.addToBackStack(null);
    transaction.commit();

When I now rotate the screen once in fragment B and press return, the old fragment A will be restored without any problems (it will use savedinstancestate bundle to restore its state in onactivitycreated)

Now comes the interesting part

When I rotate the screen and press back more than once in fragment B, I get a NullPointerException because int [] data = savedinstancestate.getintarray (state_data); Return null in onactivitycreated

How can I solve this problem? My only other way is through persistent storage (preference or dB), but this seems very inappropriate for use cases

Edit / additional information: the package itself is not empty, it is only empty

resolvent:

OK, I found the answer:

When fragment B is active, the following methods in fragment A are called when the rotation changes: onsaveinstancestate(), onattach(), and oncreate()

Because I am restoring my state in onactivitycreated (which is actually recommended by SDK!) I lost the variables stored in the bundle after the first rotation, because they will never be loaded into local variables and then stored in the next onsaveinstancestate. Therefore, when I try to retrieve them after the second rotation, these values are null

Solution: restore the variables in oncreate() so that they are available when onsaveinstancestate is called again