Не подгружаются данные с Firebase

При попытке вывести данные из Firebase выдается ошибка. В чем может быть проблема? P.S. Если вручную формировать данные, то все работает.

Лог ошибок:

`FATAL EXCEPTION: main Process: com.example.gukov.guap, PID: 3760 java.lang.NullPointerException: Attempt to invoke virtual method 'void com.example.gukov.guap.DirectionAdapter.notifyDataSetChanged()' on a null object reference

at com.example.gukov.guap.SearchFragment$1.onChildAdded(SearchFragment.java:122)

Код адаптера DirectionAdapter:

public class DirectionAdapter extends RecyclerView.Adapter<DirectionAdapter.DirectionViewHolder> {
private List<Direction> directionList;
public DirectionAdapter(List<Direction> directionList) {
    this.directionList = directionList;
}
@Override
public DirectionViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    return new DirectionViewHolder(LayoutInflater.from(parent.getContext()).inflate(R.layout.direction, parent, false));
}
@Override
public void onBindViewHolder(DirectionViewHolder holder, int position) {
    Direction direction = directionList.get(position);
    holder.textViewDirectionTitle.setText(direction.directionTitle);
    holder.textViewDirectionCount.setText(direction.directionCount);
}
@Override
public int getItemCount() {
    return directionList.size();
}
class DirectionViewHolder extends RecyclerView.ViewHolder {
    TextView textViewDirectionTitle, textViewDirectionCount;
    public DirectionViewHolder(View itemView) {
        super(itemView);

        textViewDirectionTitle = itemView.findViewById(R.id.textViewDirectionTitle);
        textViewDirectionCount = itemView.findViewById(R.id.textViewDirectionCount);
    }
}}

Код Direction:

public class Direction {
String directionCount;
String directionTitle, key;
public Direction() {
}
public Direction(String directionCount, String directionTitle, String key) {
    this.directionCount = directionCount;
    this.directionTitle = directionTitle;
    this.key = key;
}}

Код SearchFragment:

public class SearchFragment extends Fragment implements View.OnClickListener {
RecyclerView recyclerView;
DirectionAdapter adapter;
List<Direction> directionList;
private FirebaseAuth mAuth;
private FirebaseDatabase database;
private DatabaseReference myRef;
private FirebaseUser user;
public SearchFragment() {
    // Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    // инициализация FirebaseAuth
    mAuth = FirebaseAuth.getInstance();
    user = mAuth.getInstance().getCurrentUser();
    database = FirebaseDatabase.getInstance();
    myRef = database.getReference("directions");

    View rootView = inflater.inflate(R.layout.fragment_search, container, false);
    FloatingActionButton fabAdd = (FloatingActionButton) rootView.findViewById(R.id.fabAdd);
    fabAdd.setOnClickListener(this);

    directionList = new ArrayList<>();
    recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView);
    recyclerView.setHasFixedSize(true);
    LinearLayoutManager lim = new LinearLayoutManager(getActivity().getApplication().getApplicationContext());
    lim.setOrientation(LinearLayoutManager.VERTICAL);
    recyclerView.setLayoutManager(lim);

    DirectionAdapter adapter = new DirectionAdapter(directionList);
    recyclerView.setAdapter(adapter);
    updateList();

    return rootView;
}
//если вручную заполнить
//    private void createResult() {
//
//        for (int i = 0; i < 10; i++) {
//            directionList.add(new Direction("title","key","12"));
//        }
//    }
@Override
public void onClick(View v) {
    switch (v.getId()) {
        case R.id.fabAdd:
            Intent intent = new Intent(getContext(), AddMeetActivity.class);
            startActivity(intent);
            break;
        default:
            break;
    }
}
// Проверка, залогинен ли уже текущий пользователь
@Override
public void onStart() {
    super.onStart();
    FirebaseUser currentUser = mAuth.getCurrentUser();
    updateUI(currentUser);
}
// обновление пользовательского интерфейся
private void updateUI(FirebaseUser user) {
    if (user != null) {
        //
    } else {
        getActivity().findViewById(R.id.fabAdd).setVisibility(View.GONE);
    }
}
private void updateList() {
    myRef.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            directionList.add(dataSnapshot.getValue(Direction.class));
            adapter.notifyDataSetChanged();
        }
        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {
            Direction model = dataSnapshot.getValue(Direction.class);
            int index = getItemIndex(model);
            directionList.set(index, model);
            adapter.notifyItemChanged(index);
        }
        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {
            Direction model = dataSnapshot.getValue(Direction.class);
            int index = getItemIndex(model);
            directionList.remove(index);
            adapter.notifyItemRemoved(index);
        }
        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {
        }
        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });
}
private int getItemIndex(Direction direction) {
    int index = -1;
    for (int i= 0; i < directionList.size(); i++) {
        if (directionList.get(i).key.equals(direction.key)) {
            index = i;
            break;
        }
    }
    return index;
}}