RecyclerView ничего не показывает

Question

Я попытался реализовать новый RecyclerView, но он ничего не показывает. Я прошел через другие подобные вопросы и убедился, что я не совершаю те же ошибки. Пожалуйста, помогите мне найти то, что мне не хватает здесь.

Также дайте мне знать, если вам нужны другие файлы.

MainActivity

public class MainActivity extends ActionBarActivity { 

    private Toolbar toolbar; 

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

     toolbar = (Toolbar) findViewById(R.id.app_bar); 
     setSupportActionBar(toolbar); 

     getSupportActionBar().setDisplayHomeAsUpEnabled(true); 

     NavigationDrawerFragment navigationDrawerFragment = (NavigationDrawerFragment)  getSupportFragmentManager().findFragmentById(R.id.fragment_navigation_drawer); 
     navigationDrawerFragment.setup((DrawerLayout)findViewById(R.id.drawer_layout), toolbar); 

    } 

} 

NavigationDrawerFragment

public class NavigationDrawerFragment extends Fragment { 

private RecyclerView recyclerView; 
DrawerLayout drawerLayout; 
ActionBarDrawerToggle actionBarDrawerToggle; 
private NavigationDrawerViewAdapter navigationDrawerViewAdapter; 

public NavigationDrawerFragment() { 
    // Required empty public constructor 
} 


@Override 
public View onCreateView(LayoutInflater inflater, ViewGroup container, 
         Bundle savedInstanceState) { 
    // Inflate the layout for this fragment 
    View layout = inflater.inflate(R.layout.fragment_navigation_drawer, container, false); 
    recyclerView = (RecyclerView) layout.findViewById(R.id.rvDrawerList); 
    navigationDrawerViewAdapter = new NavigationDrawerViewAdapter(getActivity(), getNavigationDrawerData()); 
    recyclerView.setAdapter(navigationDrawerViewAdapter); 
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity())); 
    return layout; 
} 

public List<NavigationDrawerItem> getNavigationDrawerData() { 

    List<NavigationDrawerItem> navigationDrawerItemList = new ArrayList<>(); 
    int[] imageIds = {R.mipmap.ic_launcher, R.mipmap.ic_launcher, R.mipmap.ic_launcher, R.mipmap.ic_launcher, R.mipmap.ic_launcher}; 
    String[] titles = {"Title 1", "Title 2", "Title 3", "Title 4", "Title 5"}; 

    for (int i = 0; i < titles.length ; i++){ 
     NavigationDrawerItem navigationDrawerItem = new NavigationDrawerItem(imageIds[i], titles[i], titles[i]); 
     navigationDrawerItemList.add(navigationDrawerItem); 
    } 

    return navigationDrawerItemList; 
} 


public void setup(DrawerLayout drawerLayout, final Toolbar toolbar) { 

    this.drawerLayout = drawerLayout; 
    this.actionBarDrawerToggle = new ActionBarDrawerToggle(getActivity(), drawerLayout, toolbar, R.string.drawer_open, R.string.drawer_close) { 
     @Override 
     public void onDrawerOpened(View drawerView) { 
      super.onDrawerOpened(drawerView); 
     } 

     @Override 
     public void onDrawerClosed(View drawerView) { 
      super.onDrawerClosed(drawerView); 
     } 

    }; 
    drawerLayout.setDrawerListener(actionBarDrawerToggle); 
    drawerLayout.post(new Runnable() { 
     @Override 
     public void run() { 
      actionBarDrawerToggle.syncState(); 
     } 
    }); 
} 
} 

NavigationDrawerViewAdapter

public class NavigationDrawerViewAdapter extends RecyclerView.Adapter<NavigationDrawerViewAdapter.NavigationDrawerViewHolder> { 

// Declaring Variable to Understand which View is being worked on, IF the view under inflation and population is header or Item 
private static final int TYPE_HEADER = 0; 
private static final int TYPE_ITEM = 1; 

private LayoutInflater layoutInflater; 
List<NavigationDrawerItem> navigationDrawerItemList = new ArrayList<NavigationDrawerItem>(); 

public NavigationDrawerViewAdapter(Context context, List<NavigationDrawerItem> navigationDrawerItemList) { 
    layoutInflater = LayoutInflater.from(context); 
} 

@Override 
public NavigationDrawerViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 
    View view = layoutInflater.inflate(R.layout.item_navigation_drawer, parent, false); 
    NavigationDrawerViewHolder navigationDrawerViewHolder = new NavigationDrawerViewHolder(view); 
    return navigationDrawerViewHolder; 
} 

@Override 
public void onBindViewHolder(NavigationDrawerViewHolder holder, int position) { 
    NavigationDrawerItem navigationDrawerItem = navigationDrawerItemList.get(position); 
    holder.ivImage.setImageResource(navigationDrawerItem.getImageId()); 
    holder.tvTitle.setText(navigationDrawerItem.getTitle()); 
    holder.tvDescription.setText(navigationDrawerItem.getDescription()); 
} 

@Override 
public int getItemCount() { 
    return navigationDrawerItemList.size(); 
} 

class NavigationDrawerViewHolder extends RecyclerView.ViewHolder { 

    ImageView ivImage; 
    TextView tvTitle; 
    TextView tvDescription; 

    public NavigationDrawerViewHolder(View itemView) { 
     super(itemView); 

     ivImage = (ImageView) itemView.findViewById(R.id.ivImage); 
     tvTitle = (TextView) itemView.findViewById(R.id.tvTitle); 
     tvDescription = (TextView) itemView.findViewById(R.id.tvDescription); 

    } 
} 
} 

Answer 1

navigationDrawerItemList в NavigationDrawerViewAdapter не ссылается в список, который вы прошли от NavigationDrawerFragment, добавьте строку
this.navigationDrawerItemList =navigationDrawerItemList
к NavigationDrawerViewAdapters строителю.