Android FirebaseRecyclerAdapter未填充RecyclerView

在堆栈溢出时，我没有通过类似问题寻找任何运气。我正在尝试建立一个活动，以允许将搜索功能集成到我的Firebase实时数据库中。

我正在尝试使用a FirebaseRecyclerAdapter，以便在搜索小部件上单击回车按钮时，仅使用“ / users”节点中的孩子的名字来填充RecyclerView。

我能够检索数据快照，但是无法获取适配器来填充RecyclerView。

这是我的活动：

package calypsodating.android.com.calypso;

import android.app.SearchManager;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.view.ViewGroup;
import android.widget.SearchView;
import android.widget.TextView;

import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.firebase.ui.database.FirebaseRecyclerOptions;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.FirebaseUser;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.Query;
import com.google.firebase.database.ValueEventListener;

import calypsodating.android.com.calypso.models.User;

public class AddFriendsActivity extends AppCompatActivity {

    private static final String TAG = "AddFriendsActivity";
    private SearchManager mSearchManager;
    private SearchView mSearchView;
    private RecyclerView mRecyclerView;

    private DatabaseReference mDatabase;
    private FirebaseAuth mAuth;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        Log.d(TAG, "onCreate: starts");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_add_friends);

        mDatabase = FirebaseDatabase.getInstance().getReference().child("users");
        mAuth = FirebaseAuth.getInstance();
        FirebaseUser user = mAuth.getCurrentUser();


        mDatabase.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                Log.d(TAG, "onDataChange: starts");
                Log.d(TAG, "onDataChange: " + dataSnapshot);
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

        mSearchManager = (SearchManager) getSystemService(Context.SEARCH_SERVICE);
        mSearchView = findViewById(R.id.searchView);
        mSearchView.setSearchableInfo(mSearchManager.getSearchableInfo(getComponentName()));
        mSearchView.setIconifiedByDefault(false);

        mRecyclerView = findViewById(R.id.recyclerView_resultList);
        mRecyclerView.setHasFixedSize(true);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));


        //Get the intent, verify the action and get the query
        Intent intent = getIntent();
        if(Intent.ACTION_SEARCH.equals(intent.getAction())){

            String query = intent.getStringExtra(SearchManager.QUERY);
            searchFriends(query);

        }
    }


    private void searchFriends(String q){
        Log.d(TAG, "searchFriends: starts");
        Query userQuery = mDatabase.orderByKey();
        Log.d(TAG, "searchFriends: userQuery = " + userQuery);
        FirebaseRecyclerOptions<User> options =
                new FirebaseRecyclerOptions.Builder<User>()
                        .setQuery(userQuery, User.class)
                        .build();

        FirebaseRecyclerAdapter<User, UserViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<User, UserViewHolder>(options) {
            @Override
            protected void onBindViewHolder(@NonNull UserViewHolder holder, int position, @NonNull User model) {
                Log.d(TAG, "onBindViewHolder: starts");
                holder.setDetails(model.getFirstName());
            }

            @Override
            public UserViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
                Log.d(TAG, "onCreateViewHolder: starts");
                return null;
            }


        };

        mRecyclerView.setAdapter(firebaseRecyclerAdapter);
        Log.d(TAG, "searchFriends: recyclerview called");

    }


    // View Holder Class
    public  class UserViewHolder extends RecyclerView.ViewHolder{

        View mView;

        public UserViewHolder(View itemView) {
            super(itemView);
            mView = itemView;
        }

        public void setDetails( String userName){
            Log.d(TAG, "setDetails: starts");
            TextView user_name = mView.findViewById(R.id.textView_searchResultName);
            user_name.setText(userName);
        }

    }

}

这是我的布局文件：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="calypsodating.android.com.calypso.AddFriendsActivity">

    <SearchView
        android:id="@+id/searchView"
        android:layout_width="368dp"
        android:layout_height="44dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="16dp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"/>


    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerView_resultList"
        android:layout_width="0dp"
        android:layout_height="389dp"
        android:layout_marginBottom="8dp"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"></android.support.v7.widget.RecyclerView>

    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="8dp"
        android:text="Button"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/searchView"/>
</android.support.constraint.ConstraintLayout>

这是应该填充回收站的相关列表布局：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:app="http://schemas.android.com/apk/res-auto"
                android:layout_width="match_parent"
                android:layout_height="match_parent">

    <ImageView
        android:id="@+id/imageView_searchResultPhoto"
        android:layout_width="100dp"
        android:layout_height="100dp"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true"
        app:srcCompat="@drawable/com_facebook_profile_picture_blank_square"/>

    <TextView
        android:id="@+id/textView_searchResultName"
        android:layout_width="200dp"
        android:layout_height="50dp"
        android:layout_alignParentTop="true"
        android:layout_toEndOf="@+id/imageView_searchResultPhoto"
        android:layout_toRightOf="@+id/imageView_searchResultPhoto"
        android:text="TextView"
        android:textSize="30sp"/>
</RelativeLayout>

这是logcat，您可以看到数据快照已成功检索：

02-07 19:59:53.297 7037-7037/calypsodating.android.com.calypso D/AddFriendsActivity: onCreate: starts
02-07 19:59:53.300 7037-7037/calypsodating.android.com.calypso V/FA: onActivityCreated
02-07 19:59:53.468 7037-7055/calypsodating.android.com.calypso V/FA: Activity resumed, time: 25910369
02-07 19:59:53.472 7037-7055/calypsodating.android.com.calypso D/FA: Logging event (FE): screen_view(_vs), Bundle[{firebase_event_origin(_o)=auto, firebase_previous_class(_pc)=ProfileCreationPageOne, firebase_previous_id(_pi)=-1873360491649842747, firebase_screen_class(_sc)=AddFriendsActivity, firebase_screen_id(_si)=-1873360491649842746}]
02-07 19:59:53.552 7037-7037/calypsodating.android.com.calypso E/RecyclerView: No adapter attached; skipping layout
02-07 19:59:53.558 7037-7037/calypsodating.android.com.calypso D/AddFriendsActivity: onDataChange: starts
02-07 19:59:53.558 7037-7037/calypsodating.android.com.calypso D/AddFriendsActivity: onDataChange: DataSnapshot { key = users, value = {5={lastName=Tarney, firstName=Nicole}, 4={lastName=Booker, firstName=Hailey}, 1={lastName=Smith, firstName=Kelly}, P18G8q2AHfV8fI13cS0TpnnkFqa2={lastName=Ak, firstName=Osman, gender=Male, age=25}, 3={lastName=Williams, firstName=Brittney}, 2={lastName=Johnson, firstName=Sara}} }
02-07 19:59:53.581 7037-7077/calypsodating.android.com.calypso D/EGL_emulation: eglMakeCurrent: 0xa82058a0: ver 2 0 (tinfo 0xa8203400)
02-07 19:59:53.633 7037-7077/calypsodating.android.com.calypso D/EGL_emulation: eglMakeCurrent: 0xa82058a0: ver 2 0 (tinfo 0xa8203400)
02-07 19:59:53.664 7037-7077/calypsodating.android.com.calypso D/EGL_emulation: eglMakeCurrent: 0xa82058a0: ver 2 0 (tinfo 0xa8203400)
02-07 19:59:53.697 7037-7077/calypsodating.android.com.calypso D/EGL_emulation: eglMakeCurrent: 0xa82058a0: ver 2 0 (tinfo 0xa8203400)
02-07 19:59:53.747 7037-7037/calypsodating.android.com.calypso W/IInputConnectionWrapper: finishComposingText on inactive InputConnection
02-07 19:59:53.749 7037-7077/calypsodating.android.com.calypso D/EGL_emulation: eglMakeCurrent: 0xa82058a0: ver 2 0 (tinfo 0xa8203400)
02-07 19:59:53.795 7037-7077/calypsodating.android.com.calypso D/OpenGLRenderer: endAllActiveAnimators on 0xa83ee000 (RippleDrawable) with handle 0x840b6ba0
02-07 19:59:53.814 7037-7037/calypsodating.android.com.calypso E/RecyclerView: No adapter attached; skipping layout
02-07 19:59:54.154 7037-7037/calypsodating.android.com.calypso E/RecyclerView: No adapter attached; skipping layout
02-07 19:59:57.165 7037-7037/calypsodating.android.com.calypso E/RecyclerView: No adapter attached; skipping layout
02-07 19:59:58.190 7037-7055/calypsodating.android.com.calypso V/FA: Recording user engagement, ms: 4724
02-07 19:59:58.201 7037-7037/calypsodating.android.com.calypso D/AddFriendsActivity: onCreate: starts
02-07 19:59:58.202 7037-7037/calypsodating.android.com.calypso V/FA: onActivityCreated
02-07 19:59:58.215 7037-7055/calypsodating.android.com.calypso V/FA: Activity paused, time: 25915081
02-07 19:59:58.238 7037-7037/calypsodating.android.com.calypso D/AddFriendsActivity: searchFriends: starts
02-07 19:59:58.240 7037-7037/calypsodating.android.com.calypso D/AddFriendsActivity: searchFriends: userQuery = com.google.firebase.database.Query@7a6036d
02-07 19:59:58.250 7037-7055/calypsodating.android.com.calypso D/FA: Logging event (FE): user_engagement(_e), Bundle[{firebase_event_origin(_o)=auto, engagement_time_msec(_et)=4724, firebase_screen_class(_sc)=AddFriendsActivity, firebase_screen_id(_si)=-1873360491649842746}]
02-07 19:59:58.259 7037-7037/calypsodating.android.com.calypso D/AddFriendsActivity: searchFriends: recyclerview called
02-07 19:59:58.274 7037-7042/calypsodating.android.com.calypso I/art: Do partial code cache collection, code=27KB, data=31KB
02-07 19:59:58.275 7037-7042/calypsodating.android.com.calypso I/art: After code cache collection, code=27KB, data=31KB
02-07 19:59:58.275 7037-7042/calypsodating.android.com.calypso I/art: Increasing code cache capacity to 128KB
02-07 19:59:58.316 7037-7055/calypsodating.android.com.calypso V/FA: Activity resumed, time: 25915167
02-07 19:59:58.318 7037-7055/calypsodating.android.com.calypso D/FA: Logging event (FE): screen_view(_vs), Bundle[{firebase_event_origin(_o)=auto, firebase_previous_class(_pc)=AddFriendsActivity, firebase_previous_id(_pi)=-1873360491649842746, firebase_screen_class(_sc)=AddFriendsActivity, firebase_screen_id(_si)=-1873360491649842745}]
02-07 19:59:58.340 7037-7037/calypsodating.android.com.calypso D/AddFriendsActivity: onDataChange: starts
02-07 19:59:58.340 7037-7037/calypsodating.android.com.calypso D/AddFriendsActivity: onDataChange: DataSnapshot { key = users, value = {5={lastName=Tarney, firstName=Nicole}, 4={lastName=Booker, firstName=Hailey}, 1={lastName=Smith, firstName=Kelly}, 3={lastName=Williams, firstName=Brittney}, 2={lastName=Johnson, firstName=Sara}} }
02-07 19:59:58.350 7037-7077/calypsodating.android.com.calypso D/EGL_emulation: eglMakeCurrent: 0xa82058a0: ver 2 0 (tinfo 0xa8203400)
02-07 19:59:58.530 7037-7037/calypsodating.android.com.calypso W/IInputConnectionWrapper: finishComposingText on inactive InputConnection
02-07 20:00:03.419 7037-7055/calypsodating.android.com.calypso V/FA: Inactivity, disconnecting from the service
02-07 20:04:51.387 7037-7052/calypsodating.android.com.calypso I/FirebaseAuth: [FirebaseAuth:] Loading module via FirebaseOptions.
02-07 20:04:51.387 7037-7052/calypsodating.android.com.calypso I/FirebaseAuth: [FirebaseAuth:] Preparing to create service connection to gms implementation

我为似乎很简单的答案而感到困惑。我在网上看过，但是大多数答案都包含过时的firebaseUI版本，这些版本使用的方法我什至在文档中都看不到（例如：）populateViewHolder()。任何帮助将不胜感激。