将数据从 firebase 数据库检索到 Recyclerview 时应用程序崩溃

Question

当我尝试将应用程序中的数据从 firebase 检索到 RecyclerView 并且我的应用程序崩溃时，我在 logcat 中收到此消息。下面是我用来从 firebase 数据库中检索数据的 java 代码。应用程序显示空白屏幕，当我在真实设备上打开它时，它一直在崩溃。有没有其他方法可以做到这一点？

在 Android 4.1 之前，方法 int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) 会错误地覆盖包私有方法 在 android.widget.ListView 中

public class Home extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    FirebaseDatabase database;
    DatabaseReference category;
    TextView txtFullName;

    RecyclerView recycler_menu;
    RecyclerView.LayoutManager layoutManager;
    @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.setDrawerListener(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);
        loadMenu();
    }

    private void loadMenu() {
        FirebaseRecyclerAdapter<Category,MenuViewHolder> adapter=new FirebaseRecyclerAdapter<Category, MenuViewHolder>(Category.class,R.layout.menu_item,MenuViewHolder.class,category) {
            @Override
            protected void populateViewHolder(MenuViewHolder viewHolder, Category model, int position) {
               viewHolder.txtMenuName.setText(model.getName());
                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) {
                        Toast.makeText(Home.this,""+clickItem.getName(),Toast.LENGTH_SHORT).show();
                    }
                });
            }
        };
        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_orders) {

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

        } 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;
    }
}

Answer 1

尝试在您的回收站视图中使用此适配器

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;
import android.widget.Toast;

import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;

import java.util.ArrayList;
import java.util.List;

import illumine.ibecome.R;

public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.ViewHolder> {

    private Context mContext;
    private DatabaseReference mDatabaseReference;
    private ChildEventListener mChildEventListener;

    private List<String> mCommentIds = new ArrayList<>();
    private List<MyModel> mComments = new ArrayList<>();
    private static final String TAG = "ActivityName";

    public MyRecyclerViewAdapter(final Context context, DatabaseReference ref) {
        mContext = context;
        mDatabaseReference = ref;

        ChildEventListener childEventListener = new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {

                // A new comment has been added, add it to the displayed list
                MyModel comment = dataSnapshot.getValue(MyModel.class);
//                Log.d(TAG, "onChildAdded:" + dataSnapshot.getKey()+" with module: "+comment.modules.get(0));
                // [START_EXCLUDE]
                // Update RecyclerView

                mCommentIds.add(dataSnapshot.getKey());
                mComments.add(comment);
                notifyItemInserted(mComments.size() - 1);

            }

            @Override
            public void onChildChanged(DataSnapshot dataSnapshot, String previousChildName) {
                Log.d(TAG, "onChildChanged:" + dataSnapshot.getKey());
                // A comment has changed, use the key to determine if we are displaying this
                // comment and if so displayed the changed comment.
                MyModel newComment = dataSnapshot.getValue(MyModel.class);

                String commentKey = dataSnapshot.getKey();

                // [START_EXCLUDE]
                int commentIndex = mCommentIds.indexOf(commentKey);
                if (commentIndex > -1) {
                    // Replace with the new data
                    mComments.set(commentIndex, newComment);

                    // Update the RecyclerView
                    notifyItemChanged(commentIndex);
                } else {
                    Log.w(TAG, "onChildChanged:unknown_child:" + commentKey);
                }
                // [END_EXCLUDE]
            }

            @Override
            public void onChildRemoved(DataSnapshot dataSnapshot) {
                Log.d(TAG, "onChildRemoved:" + dataSnapshot.getKey());

                // A comment has changed, use the key to determine if we are displaying this
                // comment and if so remove it.
                String commentKey = dataSnapshot.getKey();

                // [START_EXCLUDE]
                int commentIndex = mCommentIds.indexOf(commentKey);
                if (commentIndex > -1) {
                    // Remove data from the list
                    mCommentIds.remove(commentIndex);
                    mComments.remove(commentIndex);

                    // Update the RecyclerView
                    notifyItemRemoved(commentIndex);
                } else {
                    Log.w(TAG, "onChildRemoved:unknown_child:" + commentKey);
                }
                // [END_EXCLUDE]
            }

            @Override
            public void onChildMoved(DataSnapshot dataSnapshot, String previousChildName) {
                Log.d(TAG, "onChildMoved:" + dataSnapshot.getKey());


            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                Log.w(TAG, "postComments:onCancelled", databaseError.toException());
                Toast.makeText(mContext, "Failed to load interventions.",
                        Toast.LENGTH_SHORT).show();
            }
        };
        ref.addChildEventListener(childEventListener);
        // [END child_event_listener_recycler]

        // Store reference to listener so it can be removed on app stop
        mChildEventListener = childEventListener;
    }
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(mContext);
        View view = inflater.inflate(R.layout.item_view, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        MyModel comment = mComments.get(position);

        holder.name_tv.setText(comment.name);
        holder.details_tv.setText(comment.description);
    }

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

    public void cleanupListener() {
        if (mChildEventListener != null) {
            mDatabaseReference.removeEventListener(mChildEventListener);
        }
    }
    public MyModel getItem(int position){
        return mComments.get(position);
    }
    public class ViewHolder extends RecyclerView.ViewHolder {
        TextView name_tv,details_tv;
        View parent;

        public ViewHolder(View rootView) {
            super(rootView);

            parent = rootView;

            name_tv= (TextView) rootView.findViewById(R.id.name_tv);
            details_tv = (TextView)rootView.findViewById(R.id.details_tv);

        }
    }
}