NULL in Adapter in Fragment (FragmentPagerAdapter) after screen rotation

Question

I was looking answer in similar topics but nothing works for me. I have Activity which has a fragment. This fragment has adapter. Everything is fine even if I rotate screen, but when I rotate screen and try to update adapter (for example by sort items in adapter - method sort) I get NULL on adapter.

When Activity starts first time this is happening:

ON CREATE (ACTIVITY)
    SETUP VIEW PAGER (ACTIVITY)
        CONSTRUCTOR (FRAGMENT)
        SET DATA IN ADAPTER (ACTIVITY)  
        ON CREATE (FRAGMENT)
            CREATE ADAPTER (FRAGMENT)
        ON CREATE VIEW (FRAGMENT)
            UPDATE ADAPTER (FRAGMENT)
        ON ACTIVITY CREATED (FRAGMENT)

In the second time when I rotate screen:

ON CREATE (ACTIVITY)
    CONSTRUCTOR (FRAGMENT)
    ON CREATE (FRAGMENT)
        CREATE ADAPTER (FRAGMENT)
    SETUP VIEW PAGER (ACTIVITY)
        CONSTRUCTOR (FRAGMENT)
        SET DATA IN ADAPTER (ACTIVITY)
        ON CREATE VIEW (FRAGMENT)
            UPDATE ADAPTER (FRAGMENT)
        ON ACTIVITY CREATED (FRAGMENT)

So the problem is that in activity method super.onCreate(savedInstanceState) the fragment is recreated istelf. I was trying pass NULL for super.onCreate(null) and also checking if savedInstance is NULL, changing FragmentPagerAdapter for FragmentStatePagerAdapter, and many others things. What I want to do is save and get fragment, adapter in proper way or just make activity start everytime like in the first time.

PART OF MAIN ACTIVITY

public class MainActivity extends AppCompatActivity {

    private TabLayout tabLayout;
    private ViewPager viewPager;
    SongsFragment songsFragment;
    TabAdapter tabAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(null);
        setContentView(R.layout.activity_main);

        //init work

        tabAdapter = new TabAdapter(getSupportFragmentManager());
        songsFragment = new SongsFragment();
        songsFragment.setData(database.getSongs(readOption(), readOrder()));

        tabAdapter.addFragment(songsFragment, "TAB");
        viewPager.setAdapter(tabAdapter);
        tabLayout.setupWithViewPager(viewPager);
    }

    public void sort() {
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setItems(R.array.sorts, new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int which) {
                if(which == 0) writeSort("number", "ASC");
                else if(which == 1) writeSort("number", "DESC");
                else if(which == 2) writeSort("title", "ASC");
                else if(which == 3) writeSort("title", "DESC");
                songsFragment.setData(database.getSongs(readOption(), readOrder()));
                songsFragment.updateAdapter();
            }
        }).show();
    }
}

FRAGMENT

public class SongsFragment extends Fragment {

    private RecyclerView recyclerView;

    List<Song> songs = new ArrayList<>();
    SongsAdapter adapter;

    public SongsFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Log.v("TAG", "onCr");
        if(!(savedInstanceState == null || !savedInstanceState.containsKey("list"))) {
            songs = (List<Song>) savedInstanceState.getSerializable("list");
        }
        createAdapter();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        Log.v("TAG", "onCrV");
        View view = inflater.inflate(R.layout.fragment_songs, container, false);
        recyclerView = (RecyclerView) view.findViewById(R.id.fragment_songs_SongsList);
        recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        recyclerView.setAdapter(adapter);
        updateAdapter();
        return view;
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putSerializable("list", (Serializable) songs);
    }

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

    public void setData(List<Song> songs) {
        this.songs = songs;
    }

    public void createAdapter() {
        adapter = new SongsAdapter(getContext(), songs);
    }

    public void updateAdapter() {
        adapter.clear();
        adapter.addAll(songs);
        adapter.notifyDataSetChanged();
    }
}

FRAGMENT PAGER ADAPTER

public class TabAdapter extends FragmentStatePagerAdapter {

    List<Fragment> fragments = new ArrayList<>();
    List<String> titles = new ArrayList<>();

    public TabAdapter(FragmentManager manager) {
        super(manager);
    }

    @Override
    public Fragment getItem(int position) {
        return fragments.get(position);
    }

    @Override
    public int getCount() {
        return fragments.size();
    }

    @Override
    public CharSequence getPageTitle(int position) {
        return titles.get(position);
    }

    public void addFragment(Fragment fragment, String title) {
        fragments.add(fragment);
        titles.add(title);
    }
}