Crash when tapping search button in action bar (Android)

Question

I have been following this tutorial to find out how to add a search bar to my activity. Unfortunately at the moment, each time I tap on the search icon, the app crashes and restarts immediately (so I can't see an error). The only difference I can see between their code and mine, is that I am using a standard activity, whereas they are using fragments. I have tried to change my code accordingly.

This is the code in my activity:

public class AttractionsListActivity extends AppCompatActivity implements SearchView.OnQueryTextListener  {
    public static AttractionRowAdapter adapter;
    private RecyclerView mRecyclerView;
    public static SwipeRefreshLayout swipeContainer;
    public static Park parkPassed;
    private List<Attraction> attractionsList;

    @Override
    protected void onPause() {
        super.onPause();

        adapter.clearAdaptor();
    }

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

        final Intent intent = getIntent();
        parkPassed = intent.getParcelableExtra("parkPassed");
        DataManager.loadAttractions(getBaseContext(), parkPassed.name.replaceAll("\\s+",""));

        swipeContainer = (SwipeRefreshLayout) findViewById(R.id.swipeContainer);
        swipeContainer.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
            @Override
            public void onRefresh() {
                DataManager.loadAttractions(getBaseContext(), parkPassed.name.replaceAll("\\s+",""));
                adapter.clearAdaptor();
            }
        });
        swipeContainer.setColorSchemeColors(Color.parseColor("#FF2F92"),
                Color.parseColor("#0080FF"));

        this.setupRecycler();
        this.setupImageLoader();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.action_search, menu);

        final MenuItem item = menu.findItem(R.id.action_search);
        final SearchView searchView = (SearchView) MenuItemCompat.getActionView(item);
        searchView.setOnQueryTextListener(this);

        MenuItemCompat.setOnActionExpandListener(item, new MenuItemCompat.OnActionExpandListener() {
                    @Override
                    public boolean onMenuItemActionCollapse(MenuItem item) {
                        adapter.setFilter(attractionsList);
                        return true;
                    }

                    @Override
                    public boolean onMenuItemActionExpand(MenuItem item) {
                        return true;
                    }
                });
        return super.onCreateOptionsMenu(menu);
    }


    @Override
    public boolean onQueryTextChange(String newText) {
        final List<Attraction> filteredModelList = filter(attractionsList, newText);
        adapter.setFilter(filteredModelList);
        return true;
    }

    @Override
    public boolean onQueryTextSubmit(String query) {
        return false;
    }

    private List<Attraction> filter(List<Attraction> models, String query) {
        query = query.toLowerCase();

        final List<Attraction> filteredModelList = new ArrayList<>();
        for (Attraction model : models) {
            final String text = model.name.toLowerCase();
            if (text.contains(query)) {
                filteredModelList.add(model);
            }
        }
        return filteredModelList;
    }

    private void setupRecycler() {
        mRecyclerView = (RecyclerView) findViewById(R.id.attractions_recycler);
        final LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        mRecyclerView.setLayoutManager(linearLayoutManager);

        adapter = new AttractionRowAdapter(AttractionsListActivity.this, DataManager.attractionArrayList);
        mRecyclerView.setAdapter(adapter);
    }
}

And in the adapter:

public class AttractionRowAdapter extends RecyclerView.Adapter<AttractionRowHolder> {
    private List<Attraction> attractionsList;
    private Context context;

    public AttractionRowAdapter(Context context, List<Attraction> attractionsArrayList) {
        this.attractionsList = attractionsArrayList;
        this.context = context;
    }

    @Override
    public int getItemCount() {
        return (null != attractionsList ? attractionsList.size() : 0);
    }

    public void setFilter(List<Attraction> attractions) {
        attractionsList = new ArrayList<>();
        attractionsList.addAll(attractions);
        notifyDataSetChanged();
    }
}

I've only posted the relevant code. All of the necessary methods are there. Everything works fine up until I tap the search icon.

Any ideas?

Answer 1

This is never initialized in the Activity

private List<Attraction> attractionsList;

This list is being passed around as null, and most likely results in a NullPointerException at this

adapter.setFilter(attractionsList);

Which calls this

public void setFilter(List<Attraction> attractions) {
    attractionsList = new ArrayList<>();
    attractionsList.addAll(attractions);

And addAll throws a NullPointerException