java - FirebaseRecyclerAdapter DatabaseException : Can't convert object of type java. lang.String 输入帖子

Question

我正在尝试获取存储在 Firebase 数据库中的信息并以列表的形式显示它。信息被正确提取，调试器显示它存在于变量中。但是在检查它们并设置 TextView 之后，它会抛出异常:

错误日志:

com.google.firebase.database.DatabaseException: Can't convert an object of type java.lang.String to type com.dodo.seminar.Posts
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.dodo.seminar, PID: 6841
com.google.firebase.database.DatabaseException: Can't convert object of type java.lang.String to type com.dodo.seminar.Posts
    at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(com.google.firebase:firebase-database@@16.1.0:423)
    at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-database@@16.1.0:214)
    at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertToCustomClass(com.google.firebase:firebase-database@@16.1.0:79)
    at com.google.firebase.database.DataSnapshot.getValue(com.google.firebase:firebase-database@@16.1.0:212)
    at com.firebase.ui.database.FirebaseRecyclerAdapter.parseSnapshot(FirebaseRecyclerAdapter.java:151)
    at com.firebase.ui.database.FirebaseRecyclerAdapter.getItem(FirebaseRecyclerAdapter.java:140)
    at com.firebase.ui.database.FirebaseRecyclerAdapter.onBindViewHolder(FirebaseRecyclerAdapter.java:183)
    at android.support.v7.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:6781)
    at android.support.v7.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:6823)
    at android.support.v7.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:5752)
    at android.support.v7.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6019)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5858)
    at android.support.v7.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:5854)
    at android.support.v7.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2230)
    at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1557)
    at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1517)
    at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:612)
    at android.support.v7.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:3924)
    at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:3641)
    at android.support.v7.widget.RecyclerView.consumePendingUpdateOperations(RecyclerView.java:1888)
    at android.support.v7.widget.RecyclerView$1.run(RecyclerView.java:407)
    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)
    at android.view.Choreographer.doCallbacks(Choreographer.java:761)
    at android.view.Choreographer.doFrame(Choreographer.java:693)
    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)
    at android.os.Handler.handleCallback(Handler.java:873)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loop(Looper.java:193)
    at android.app.ActivityThread.main(ActivityThread.java:6669)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Database structure

public class PostsActivity extends AppCompatActivity {

    private FirebaseAuth mAuth;
    private Toolbar mToolbar;
    private DatabaseReference mDatabase;
    private DatabaseReference mUserRef;
    private FloatingActionButton mButton;
    private RecyclerView mPostsList;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_posts);
        mAuth = FirebaseAuth.getInstance();
        mButton = findViewById(R.id.posts_floatingActionButton);
        if (mAuth.getCurrentUser() != null) {
            mUserRef = FirebaseDatabase.getInstance().getReference().child("users").child(mAuth.getCurrentUser().getUid());
        }
        mDatabase = FirebaseDatabase.getInstance().getReference().child("posts");

        mPostsList = (RecyclerView) findViewById(R.id.posts_list);
        mPostsList.setHasFixedSize(true);
        mPostsList.setLayoutManager(new LinearLayoutManager(this));
    }


    @Override
    protected void onStart() {
        super.onStart();
        final FirebaseRecyclerAdapter<Posts, PostsViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Posts, PostsViewHolder>(
                Posts.class,
                R.layout.posts_single_layout,
                PostsViewHolder.class,
                mDatabase
        ) {
            @Override
            protected void populateViewHolder(final PostsViewHolder postsViewHolder, final Posts posts, int position) {
                postsViewHolder.setStartingLocation(posts.getStarting_location());
                postsViewHolder.setDestination(posts.getDestination());
                postsViewHolder.setDescription(posts.getDescription());

            }
        };

        mPostsList.setAdapter(firebaseRecyclerAdapter);

    }


    public static class PostsViewHolder extends RecyclerView.ViewHolder {

        static View mView;
        RelativeLayout parentLayout;


        public PostsViewHolder(@NonNull View itemView) {
            super(itemView);
            mView = itemView;
            parentLayout = itemView.findViewById(R.id.parent_layout);
        }

        public static void setStartingLocation(String name) {
            TextView postsTextView = (TextView) mView.findViewById(R.id.posts_single_starting_location);
            postsTextView.setText(name);
        }

        public static void setDestination(String comment) {
            TextView postsTextView = (TextView) mView.findViewById(R.id.posts_single_destination);
            postsTextView.setText(comment);
        }

        public static void setDescription(String comment) {
            TextView postsTextView = (TextView) mView.findViewById(R.id.posts_single_description);
            postsTextView.setText(comment);
        }


    }
}



public class Posts {


    private String starting_location;
    private String user_uid;
    private String destination;
    private String description;
    private String time;

    public Posts(String starting_location, String user_uid, String destination, String description, String time) {
        this.starting_location = starting_location;
        this.user_uid = user_uid;
        this.destination = destination;
        this.description = description;
        this.time = time;
    }

    public Posts() {
    }

    public String getStarting_location() {
        return starting_location;
    }

    public void setStarting_location(String startingLocation) {
        this.starting_location = startingLocation;
    }

    public String getDestination() {
        return destination;
    }

    public void setDestination(String destination) {
        this.destination = destination;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public String getUser_uid() {
        return user_uid;
    }

    public void setUser_uid(String user_uid) {
        this.user_uid = user_uid;
    }

    public String getTime() {
        return time;
    }

    public void setTime(String time) {
        this.time = time;
    }
}

Answer 1

您收到字符串并尝试将其解释为 Posts 对象。

尝试将接收到的数据存储在 String 中，并使用 Gson 从该 json 创建 Posts 对象。