Firebase：RecyclerView：没有附加适配器；跳过布局

Question

我刚开始使用 Firebase，到目前为止它非常棒。但是，当我尝试使用 Firebase UI 和 Firebase RecyclerAdapter 将我的数据挂钩到卡片视图时，我的日志猫上出现以下错误，上面写着

    $ E/RecyclerView: No adapter attached; skipping layout

这是我的 MainActivity.java

package helloworld.firebase.com.helloworld;

import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import com.firebase.ui.database.FirebaseRecyclerAdapter;
import com.google.android.gms.auth.api.Auth;
import com.google.android.gms.auth.api.signin.GoogleSignInAccount;
import com.google.android.gms.auth.api.signin.GoogleSignInOptions;
import com.google.android.gms.auth.api.signin.GoogleSignInResult;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.SignInButton;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.tasks.OnCompleteListener;
import com.google.android.gms.tasks.Task;
import com.google.firebase.auth.AuthCredential;
import com.google.firebase.auth.AuthResult;
import com.google.firebase.auth.FirebaseAuth;
import com.google.firebase.auth.GoogleAuthProvider;
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.ValueEventListener;

import org.w3c.dom.Text;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {

    TextView text1, text2 ;
    EditText edittitle, editdesc;
    Button btn, post;
    ListView mUserList;

   private RecyclerView mRecyclerView;
    private SignInButton mGooglebtn;
    private static final int RC_SIGN_IN =  1;
    private GoogleApiClient mGoogleApiClient;
    private DatabaseReference mDatabase;
    private FirebaseAuth mAuth;
    private FirebaseAuth.AuthStateListener mAuthListner;
    private FirebaseRecyclerAdapter firebaseRecyclerAdapter;
    private RecyclerView.LayoutManager mLayoutManager;



    private static final String TAG = MainActivity.class.getSimpleName();

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



        mRecyclerView = (RecyclerView) findViewById(R.id.blog_list);
        mRecyclerView.setHasFixedSize(true);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mRecyclerView.setAdapter(firebaseRecyclerAdapter);






        mGooglebtn =   (SignInButton) findViewById(R.id.googleBtn);
        edittitle = (EditText) findViewById(R.id.edit_title);
        editdesc = (EditText) findViewById(R.id.edit_desc);
        post = (Button) findViewById(R.id.post);

        post.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                startPosting();
            }
        });


        mAuth = FirebaseAuth.getInstance();
        mAuthListner = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                if (firebaseAuth.getCurrentUser() != null) {
                    Toast.makeText(MainActivity.this, "LOGGED IN", Toast.LENGTH_SHORT).show();
                        startActivity(new Intent(MainActivity.this, AccountActivity.class));
                }
            }
        };
        mDatabase = FirebaseDatabase.getInstance().getReference().child("Blog");

        final String userID = mDatabase.push().getKey();


        // Configure Google Sign In
        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build();

        mGoogleApiClient = new GoogleApiClient.Builder(getApplicationContext())
                .enableAutoManage(this, new GoogleApiClient.OnConnectionFailedListener() {
                    @Override
                    public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
                        Toast.makeText(MainActivity.this, "ERROR", Toast.LENGTH_SHORT).show();
                    }
                })
                .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
                .build();

        mGooglebtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                signIn();
            }
        });



    private void startPosting() {
        String name = edittitle.getText().toString().trim();
        String desc = editdesc.getText().toString().trim();

        DatabaseReference newPost = mDatabase.child("Blog").push();
        newPost.child("title").setValue(name);
        newPost.child("desc").setValue(desc);

    }


    protected void OnStart() {
        super.onStart();
        mAuth.addAuthStateListener(mAuthListner);

        firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<User, BlogViewHolder>(User.class,
                R.layout.blog_row,
                BlogViewHolder.class,
                mDatabase) {

            @Override
            protected void populateViewHolder(BlogViewHolder viewHolder, User model, int position) {
                viewHolder.setTitle(model.getTitle());
                viewHolder.setDesc(model.getDesc());
            }



        };

        mRecyclerView.setAdapter(firebaseRecyclerAdapter);

    }

    public static class BlogViewHolder extends RecyclerView.ViewHolder {
        View mView;
        public BlogViewHolder(View itemView) {
            super(itemView);

            mView = itemView;
        }

        public void setTitle(String title) {

            TextView posttitle = (TextView) mView.findViewById(R.id.post_title);
            posttitle.setText(title);
        }

        public void setDesc (String desc) {
            TextView postdesc = (TextView) mView.findViewById(R.id.post_desc);
            postdesc.setText(desc);
        }


    }




    private void signIn() {
        Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
        startActivityForResult(signInIntent, RC_SIGN_IN);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
            if (result.isSuccess()) {
                // Google Sign In was successful, authenticate with Firebase
                GoogleSignInAccount account = result.getSignInAccount();
                firebaseAuthWithGoogle(account);
            } else {
                // Google Sign In failed, update UI appropriately
                // ...
                Toast.makeText(this, "FAILED", Toast.LENGTH_SHORT).show();
            }
        }
    }

    private void firebaseAuthWithGoogle(GoogleSignInAccount account) {
        Log.d(TAG, "firebaseAuthWithGoogle:" + account.getId());

        AuthCredential credential = GoogleAuthProvider.getCredential(account.getIdToken(), null);
        mAuth.signInWithCredential(credential)
                .addOnCompleteListener(this, new OnCompleteListener<AuthResult>() {
                    @Override
                    public void onComplete(@NonNull Task<AuthResult> task) {
                        Log.d(TAG, "signInWithCredential:onComplete:" + task.isSuccessful());

                        Toast.makeText(MainActivity.this, "LOGGED IN", Toast.LENGTH_SHORT).show();
                        startActivity(new Intent(MainActivity.this, AccountActivity.class));
                        // If sign in fails, display a message to the user. If sign in succeeds
                        // the auth state listener will be notified and logic to handle the
                        // signed in user can be handled in the listener.
                        if (!task.isSuccessful()) {
                            Log.w(TAG, "signInWithCredential", task.getException());
                            Toast.makeText(MainActivity.this, "Authentication failed.",
                                    Toast.LENGTH_SHORT).show();
                        }
                        // ...
                    }
                });
    }


}
        //});

这是我的 User.class 文件

    package helloworld.firebase.com.helloworld;



public class User {

    public String title, desc;

    public User() {}

    public User(String title, String desc) {
        this.title = title;
        this.desc = desc;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDesc() {
        return desc;
    }

    public void setDesc(String desc) {
        this.desc = desc;
    }
}

应用程序运行完美，但没有连接 RecyclerView 适配器。这是我现在面临的唯一问题。如果有人可以提供帮助，那就太好了。在此先感谢:)

Answer 1

基于 android 生命周期回调，onStart() 仅在 onCreate() 之后被调用。在您的代码中，您尝试在初始化之前将 firebaseRecyclerAdapter 附加到适配器。

如果你想摆脱那个烦人的消息，要么在 onCreate() 中设置空适配器，要么将所有 FirebaseRecyclerAdapter 代码移到 onCreate，然后设置一个适配器 .

Answer 2

查看已解决的话题here

初始化 RecyclerView 和附加 LayoutManager 等时需要附加适配器。