recycler view is not attached blank screen

Question

whenevr clicking on foodmenu it shows blankscreen my code is properly written in firebase recyclerview adapter

Picture 1:

Picture 2 will give the error blank screen:

what changes has to be done in this foodList.java class ,i tried using firebase recycler option adapter and also set the permission of firebase database to true.it gives the no adapter attached . FoodList.java

public class FoodList extends AppCompatActivity {

    RecyclerView recycler_food;
    RecyclerView.LayoutManager layoutManager;

    FirebaseDatabase database;
    DatabaseReference foodList;

    String categoryId = "";
    FirebaseRecyclerAdapter<Food, FoodViewHolder> adapter;

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

        database = FirebaseDatabase.getInstance();
        foodList = database.getReference("Foods");

        recycler_food = (RecyclerView) findViewById(R.id.recyclerfood);
        recycler_food.setHasFixedSize(true);
        layoutManager = new LinearLayoutManager(this);
        recycler_food.setLayoutManager(layoutManager);

        if (getIntent() != null)
            categoryId = getIntent().getStringExtra("CategoryId");
        if (categoryId != null && categoryId.isEmpty()) {
            loadListFood(categoryId);
        }
    }

    private void loadListFood(String categoryId) {

        Query food = null;
        assert food != null;
        FirebaseRecyclerOptions<Food> options =
                new FirebaseRecyclerOptions.Builder<Food>()
                        .setQuery(food, Food.class).build();

        adapter = new FirebaseRecyclerAdapter<Food, FoodViewHolder>(options) {
            @Override
            public FoodViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {


                View view = LayoutInflater.from(parent.getContext())
                        .inflate(R.layout.food_item, parent, false);

                return new FoodViewHolder(view);
            }

            @Override
            protected void onBindViewHolder(@NonNull FoodViewHolder holder, int position, @NonNull Food model) {
                holder.food_name.setText(model.getName());
                Picasso.with(getBaseContext()).load(model.getImage()).into(holder.food_image);
                final Food local = model;
                holder.setItemClickListener(new ItemClickListener() {
                    @Override
                    public void onClick(View view, int position, boolean isLongClick) {
                        Toast.makeText(FoodList.this, "" + local.getName(), Toast.LENGTH_SHORT).show();
                    }
                });
            }
        };
        recycler_food.setAdapter(adapter);
        adapter.startListening();
    }
}

FoodViewHolder

public class FoodViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

    public TextView food_name;
    public ImageView food_image;

    private ItemClickListener itemClickListener;

    public void setItemClickListener(ItemClickListener itemClickListener) {
        this.itemClickListener = itemClickListener;
    }

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

        food_name = itemView.findViewById(R.id.food_name);
        food_image = itemView.findViewById(R.id.food_image);
        itemView.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        itemClickListener.onClick(view,getAdapterPosition(),false);
    }

}

Logcat Error display

   06-26 20:57:44.626 15914-15914/com.example.sharma.digimenu I/Timeline: Timeline: Activity_launch_request id:com.example.sharma.digimenu time:94010711
06-26 20:57:44.637 15914-15942/com.example.sharma.digimenu V/FA: Recording user engagement, ms: 2649
06-26 20:57:44.638 15914-15942/com.example.sharma.digimenu V/FA: Activity paused, time: 241535027
06-26 20:57:44.641 15914-15942/com.example.sharma.digimenu D/FA: Logging event (FE): user_engagement(_e), Bundle[{firebase_event_origin(_o)=auto, engagement_time_msec(_et)=2649, firebase_screen_class(_sc)=Home, firebase_screen_id(_si)=5270971596160237574}]
06-26 20:57:44.649 15914-15914/com.example.sharma.digimenu V/FA: onActivityCreated
06-26 20:57:44.682 15914-15942/com.example.sharma.digimenu D/FA: Logging event (FE): screen_view(_vs), Bundle[{firebase_event_origin(_o)=auto, firebase_previous_class(_pc)=Home, firebase_previous_id(_pi)=5270971596160237574, firebase_screen_class(_sc)=FoodList, firebase_screen_id(_si)=5270971596160237575}]
06-26 20:57:44.691 15914-15914/com.example.sharma.digimenu E/RecyclerView: No adapter attached; skipping layout
06-26 20:57:44.712 15914-15914/com.example.sharma.digimenu E/RecyclerView: No adapter attached; skipping layout
06-26 20:57:44.729 15914-15914/com.example.sharma.digimenu I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@35a28f6a time:94010814
06-26 20:57:44.731 15914-15942/com.example.sharma.digimenu V/FA: Activity resumed, time: 241535052

Answer 1

public class FoodList extends AppCompatActivity {

    RecyclerView recycler_food;
    RecyclerView.LayoutManager layoutManager;

    FirebaseDatabase database;
    DatabaseReference foodList;

    String categoryId = "";
    FirebaseRecyclerAdapter<Food, FoodViewHolder> adapter;

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

        database = FirebaseDatabase.getInstance();
        foodList = database.getReference("Foods");

        recycler_food = (RecyclerView) findViewById(R.id.recyclerfood);
        recycler_food.setHasFixedSize(true);
        layoutManager = new LinearLayoutManager(this);
        recycler_food.setLayoutManager(layoutManager);


        if (getIntent() != null)
            categoryId = getIntent().getStringExtra("CategoryId");
        if (categoryId != null && ! categoryId.isEmpty()) {
            loadListFood(categoryId);
        }

    }

    private void loadListFood(String categoryId) {

        Query food = FirebaseDatabase.getInstance().getReference("Foods").orderByChild("MenuId").equalTo(categoryId);

        FirebaseRecyclerOptions<Food> options =
                new FirebaseRecyclerOptions.Builder<Food>().setLifecycleOwner(this)
                        .setQuery(food, Food.class).build();

        adapter = new FirebaseRecyclerAdapter<Food, FoodViewHolder>(options) {
            @NonNull
            @Override
            public FoodViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

                View view = LayoutInflater.from(parent.getContext())
                        .inflate(R.layout.food_item, parent, false);
                return new FoodViewHolder(view);
            }

            @Override
            protected void onBindViewHolder(@NonNull FoodViewHolder holder, int position, @NonNull Food model) {
                holder.food_name.setText(model.getName());
                Picasso.with(getBaseContext()).load(model.getImage()).into(holder.food_image);
                final Food clickItem = model;
                //adapter.notifyDataSetChanged();
                holder.setItemClickListener(new ItemClickListener() {
                    @Override
                    public void onClick(View view, int position, boolean isLongClick) {
                        Toast.makeText(FoodList.this, "" + clickItem.getName(), Toast.LENGTH_SHORT).show();
                    }
                });
            }
        };
        recycler_food.setAdapter(adapter);

    }

}