FirebaseRecyclerAdapter 不会加载

Question

当我尝试加载我在我的应用中实现的食物列表时遇到问题。当我为应用程序充电时，列表就在那里，但当应用程序的各种食物的图像和名称时，它没有内容。我查了一下，问题是我没有调用 adapter.startListening();加载列表之前的命令，以便它可以获取我告诉它的数据，但它不识别 adapter.startListening();命令，甚至在整个代码中都输入它。

你能帮帮我吗？我的代码缺少什么？我希望代码能够识别 adapter.startListening 命令。

我的代码是（类是home.class）：

´public class Home extends AppCompatActivity 实现 NavigationView.OnNavigationItemSelectedListener {

FirebaseDatabase database;
DatabaseReference category;

TextView txtFullName;

RecyclerView recycler_menu;
RecyclerView.LayoutManager layoutManager;

FirebaseRecyclerAdapter<Category, MenuViewHolder> adapter;


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

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    toolbar.setTitle("Menú");
    setSupportActionBar(toolbar);

    // Init Firebase
    database = FirebaseDatabase.getInstance();
    category = database.getReference("Categoria");


    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.addDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);

    View headerView = navigationView.getHeaderView( 0);
    txtFullName = (TextView)headerView.findViewById(R.id.txtFullName);
    txtFullName.setText(Common.currentUser.getName());

    // Cargar el menú desde Firebase con Recycler View
    // Definir el modelo Category

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

    loadMenu();

}

private void loadMenu() {

    adapter = new FirebaseRecyclerAdapter<Category, MenuViewHolder>(Category.class, R.layout.menu_item, MenuViewHolder.class, category) {

        @Override
        protected void populateViewHolder(MenuViewHolder viewHolder, Category model, int position) {

            // Coge el nombre del usuario
            viewHolder.txtMenuName.setText(model.getName());

            // Coge imagenes de Picasso
            Picasso.with(getBaseContext()).load(model.getImage())
                    .into(viewHolder.imageView);
            final Category clickItem = model;
            viewHolder.setItemClickListener(new ItemClickListener() {

                @Override
                public void onClick(View view, int position, boolean isLongClick) {
                    // Coger la CategoryId y enviarlo a la nueva actividad
                    Intent foodList = new Intent(Home.this, FoodList.class);
                    foodList.putExtra("CategoryId",adapter.getRef(position).getKey());
                    startActivity(foodList);
                }
            });

        }

    };


    recycler_menu.setAdapter(adapter);

}


@Override
public void onBackPressed() {
    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    if (drawer.isDrawerOpen(GravityCompat.START)) {
        drawer.closeDrawer(GravityCompat.START);
    } else {
        super.onBackPressed();
    }
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.home, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {


    return super.onOptionsItemSelected(item);
}

@SuppressWarnings("StatementWithEmptyBody")
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_menu) {
        // Handle the camera action
    } else if (id == R.id.nav_cart) {

    } else if (id == R.id.nav_order) {

    } else if (id == R.id.nav_log_out) {

    }

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}

}`

FoodList.java：

`public class FoodList 扩展 AppCompatActivity {

RecyclerView recyclerView;
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);

    // Firebase
    database = FirebaseDatabase.getInstance();
    foodlist = database.getReference("Foods");

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

    // Coger Intend

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

private void loadListFood(String categoryId) {
    adapter = new FirebaseRecyclerAdapter<Food, FoodViewHolder>(Food.class,
            R.layout.food_item,
            FoodViewHolder.class,
            foodlist.orderByChild("MenuId").equalTo(categoryId)
            ) {

        @Override
        protected void populateViewHolder(FoodViewHolder viewHolder, Food model, int position) {
            viewHolder.food_name.setText(model.getName());
            Picasso.with(getBaseContext()).load(model.getImage()).into(viewHolder.food_image);

            final Food local = model;
            viewHolder.setItemClickListener(new ItemClickListener() {
                @Override
                public void onClick(View view, int position, boolean isLongClick) {
                    Toast.makeText(FoodList.this, ""+local.getName(), Toast.LENGTH_SHORT).show();
                }
            });
        }
    };

    Log.d("TAG", ""+adapter.getItemCount());
    recyclerView.setAdapter(adapter);
}

}

Answer 1

问题：

// Init Firebase
database = FirebaseDatabase.getInstance();
category = database.getReference("Categoria");

解决方案：

// Init Firebase
database = FirebaseDatabase.getInstance();
category = database.getReference().child("Categoria");