我从Firebase数据库检索了数据，并希望使用FirebaseAdapter在回收器视图中显示数据。当我使用adapter.startListening()方法时，它显示跟随错误，当我删除它时，它可以正常工作，但不加载任何内容
这是我尝试过的：
package com.andisofttechnology.myapplication.Model;
import android.os.Bundle;
import android.support.design.widget.NavigationView;
import android.support.v7.app.AppCompatActivity;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
import com.andisofttechnology.myapplication.Common.Common;
import com.andisofttechnology.myapplication.Interface.ItemClickListener;
import com.andisofttechnology.myapplication.R;
import com.andisofttechnology.myapplication.ViewHolder.MenuViewHolder;
import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.squareup.picasso.Picasso;
import java.util.Locale;
public class Home extends AppCompatActivity
implements NavigationView.OnNavigationItemSelectedListener {
FirebaseDatabase database;
DatabaseReference category;
TextView txtFullName;
RecyclerView recycler_menu;
TextView menu_name;
LinearLayoutManager layoutManager;
/* FirebaseRecyclerAdapter<Category,MenuViewHolder> firebaseRecyclerAdapter;*/
private TextView txtMenuName;
FirebaseRecyclerAdapter<Category,MenuViewHolder> firebaseRecyclerAdapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
toolbar.setTitle("Menu");
setSupportActionBar(toolbar);
//Init Firebase
database = FirebaseDatabase.getInstance();
category = database.getReference("Category");
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);
//Set Name for User
View headerView = navigationView.getHeaderView(0);
txtFullName = (TextView)headerView.findViewById(R.id.txtFullName);
txtFullName.setText(Common.currentUser.getName());
//Load Menu
recycler_menu = (RecyclerView)findViewById(R.id.recycler_menu);
recycler_menu.setHasFixedSize(true);
layoutManager = new LinearLayoutManager(this);
recycler_menu.setLayoutManager(layoutManager);
layoutManager = new LinearLayoutManager(this);
loadMenu();
}
private void loadMenu() {
Query query = FirebaseDatabase.getInstance()
.getReference()
.child("Category");
FirebaseRecyclerOptions<Category> options =
new FirebaseRecyclerOptions.Builder<Category>()
.setQuery(query, Category.class)
.build();
FirebaseRecyclerAdapter firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Category, MenuViewHolder>(options) {
@Override
public MenuViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext())
.inflate(R.layout.menu_item, parent, false);
return new MenuViewHolder(view);
}
@Override
protected void onBindViewHolder(MenuViewHolder holder, int position, Category model) {
txtMenuName = (TextView)findViewById(R.id.menu_name);
holder.txtMenuName.setText(model.getName());
/* Picasso
.with(getBaseContext())
.load(<model.getName()>)
.resize(2048, 1600)
.onlyScaleDown() // the image will only be resized if it's bigger than 2048x 1600 pixels.
.into(<ImageView>);*/
Picasso.with(getBaseContext()).load(model.getName()).into(holder.imageView);
final Category clickItem = model;
holder.setItemClickListener(new ItemClickListener() {
@Override
public void onClick(View view, int position, boolean isLongClick) {
Toast.makeText(Home.this, ""+clickItem.getName(),Toast.LENGTH_SHORT).show();
}
});
}
};
/*firebaseRecyclerAdapter.startListening();*/
recycler_menu.setAdapter(firebaseRecyclerAdapter);
/* firebaseRecyclerAdapter.stopListening();*/
}
@Override
public void onStart() {
super.onStart();
firebaseRecyclerAdapter.startListening();
}
@Override
public void onStop(){
super.onStop();
firebaseRecyclerAdapter.startListening();
}
@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) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
/* if (id == R.id.action_settings) {
return true;
}*/
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_camera) {
// Handle the camera action
} else if (id == R.id.nav_gallery) {
} else if (id == R.id.nav_slideshow) {
} else if (id == R.id.nav_manage) {
} else if (id == R.id.nav_share) {
} else if (id == R.id.nav_send) {
}*/
DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
drawer.closeDrawer(GravityCompat.START);
return true;
}
}
MenuViewHolder.class
package com.andisofttechnology.myapplication.ViewHolder;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import com.andisofttechnology.myapplication.Interface.ItemClickListener;
import com.andisofttechnology.myapplication.R;
/**
* Created by fullfocus on 9/6/2018.
*/
public class MenuViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
public TextView txtMenuName;
public ImageView imageView;
private ItemClickListener itemClickListener;
public MenuViewHolder(View itemView) {
super(itemView);
txtMenuName = (TextView)itemView.findViewById(R.id.menu_name);
imageView = (ImageView)itemView.findViewById(R.id.menu_image);
itemView.setOnClickListener(this);
}
public void setItemClickListener(ItemClickListener itemClickListener){
this.itemClickListener = itemClickListener;
}
@Override
public void onClick(View view) {
itemClickListener.onClick(view,getAdapterPosition(),false);
}
}
我已经阅读了与此相关的问题，但找不到适合我的解决方案。有人可以告诉我错误是什么吗？
答案 0 :(得分：1)
要解决此问题，请更改以下代码行：
FirebaseRecyclerAdapter firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Category, MenuViewHolder>(options)
到
firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Category, MenuViewHolder>(options)
您已经将变量firebaseRecyclerAdapter设置为全局变量。