Restore scroll position - android-recyclerview

Question

I have a simple fragment which retrieve data from Firebase database.
I use firebase recycler view to display retrieving data. And after scrolling or screen rotation I can't force recycler view (or linear layout manager) restore scroll position.
I found here some answers but they don't work.
My code is:
public class NewsListFragment extends ParentNewsFragment {
static int color_naval, color_black;
private boolean mProcessLikes = false;
private DatabaseReference mDatabaseLikes;
private DatabaseReference mDatabaseViews;
private FirebaseAuth mAuth;
private int position = 0;
public static NewsListFragment getInstance() {
return new NewsListFragment();
}
#Override
public void onCreate(#Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mDatabaseReference = FirebaseDatabase.getInstance().getReference()
.child("App_news");
mDatabaseLikes = FirebaseDatabase.getInstance().getReference().child("news_likes");
mDatabaseViews = FirebaseDatabase.getInstance().getReference().child("news_views");
mAuth = FirebaseAuth.getInstance();
mQuery = mDatabaseReference.orderByChild("pos").startAt("100");
color_naval = getResources().getColor(R.color.colorPrimary);
color_black = getResources().getColor(R.color.colorBlack);
}
#Nullable
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.rv_choose, container, false);
rv = (RecyclerView) rootView.findViewById(R.id.rv_choose);
lm = new LinearLayoutManager(getActivity());
rv.setLayoutManager(lm);
rv.setHasFixedSize(true);
return rootView;
}
#Override
public void onPause() {
super.onPause();
position = lm.findFirstVisibleItemPosition();
}
#Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putInt("position", position);
}
#Override
public void onViewStateRestored(#Nullable Bundle savedInstanceState) {
super.onViewStateRestored(savedInstanceState);
if(savedInstanceState != null) {
position = savedInstanceState.getInt("position");
}
}
#Override
public void onResume() {
super.onResume();
if (position != 0) {
lm.scrollToPosition(position);
showToast(position+"");
}
}
#Override
public void onStart() {
super.onStart();
FirebaseRecyclerAdapter<NewsList, NewsListViewHolder> adapter =
new FirebaseRecyclerAdapter<NewsList, NewsListViewHolder>(
NewsList.class,
R.layout.frag_newslist_card_view,
NewsListViewHolder.class,
mQuery
) {
#Override
protected void populateViewHolder(NewsListViewHolder viewHolder, final NewsList model, int position) {
final String post_key = getRef(position).getKey();
viewHolder.setDate(model.getDate()+",");
viewHolder.setTime(model.getTime());
viewHolder.setTitle(model.getTitle());
viewHolder.setImage(getContext(), model.getImage());
viewHolder.setEye(model.getCode());
viewHolder.setThumb(post_key);
viewHolder.thumb.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
mProcessLikes = true;
mDatabaseLikes.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (mProcessLikes){
if (dataSnapshot.child(post_key).hasChild(mAuth.getCurrentUser().getUid())){
mDatabaseLikes.child(post_key).child(mAuth.getCurrentUser().getUid())
.removeValue();
mProcessLikes = false;
}
else {
mDatabaseLikes.child(post_key).child(mAuth.getCurrentUser().getUid())
.setValue("like");
mProcessLikes = false;
}
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
}
});
viewHolder.mView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
mDatabaseViews.addValueEventListener(new ValueEventListener() {
#Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (!dataSnapshot.child(post_key).hasChild(mAuth.getCurrentUser().getUid())) {
mDatabaseViews.child(post_key).child(mAuth.getCurrentUser().getUid())
.setValue("view");
}
}
#Override
public void onCancelled(DatabaseError databaseError) {
}
});
mChooserListener.chooseNews(model.getCode());
}
});
}
};
rv.setAdapter(adapter);
}
public static class NewsListViewHolder extends RecyclerView.ViewHolder {
//some text here
}
}
method showToast in the end shows real number of position but recyclerview starts from the beginning.
any ideas?

Answer 1

Make sure you are not reloading data from the server or wherever you are retrieving data.
Add is not null check in your fragment's onCreateView or activity's onCreate like:
if(savedInstanceState != null){
...
}else{
loadData();
}

Answer 2

Replace your linear layout manager with something similar to the following. I have used this implementation many times when using RecyclerView in fragments. Let me know how it goes
LinearLayoutManager mLayoutManager = new LinearLayoutManager(getActivity());
mLayoutManager.setReverseLayout(true);
mLayoutManager.setStackFromEnd(true);
yourItem.setLayoutManager(mLayoutManager);