Firestore 回收器适配器 - 滚动后消失的项目

Question

我正在尝试为我的项目创建聊天服务，为此，我将消息存储在从服务器获取的 Firestore 数据库中，并分配将发件人 ID 与当前用户 ID 进行比较的文本。 当我开始活动时，消息会正确显示，但是当我向下滚动时，我的消息会停止显示，或者其他用户的消息会消失，这取决于是否打开了聊天帐户。

我似乎无法弄清楚为什么会发生这种情况。

我的 readMessages 函数：

private void readMessages(){
    Query query = DataRef.collection("rooms").document(roomID).collection("messages").orderBy("timestamp", Query.Direction.ASCENDING);
    FirestoreRecyclerOptions<MessageModel> options = new FirestoreRecyclerOptions.Builder<MessageModel>().setQuery(query, MessageModel.class).build();
    adapter = new FirestoreRecyclerAdapter<MessageModel, MessageAdapter.ViewHolder>(options) {
        @Override
        protected void onBindViewHolder(MessageAdapter.ViewHolder holder, int position, MessageModel model) {
            if (myUid.equals(model.getUid())) {
                Log.d(TAG, "status1");
                holder.msg_right.setText(String.valueOf(model.getMsg()));
                holder.msg_left.setVisibility(View.INVISIBLE);
                holder.profile_image.setVisibility(View.INVISIBLE);
                holder.msg_nick.setVisibility(View.INVISIBLE);
            }
            else
            {
                DataRef.collection("users").document(String.valueOf(model.getUid())).get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
                    @Override
                    public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                        DocumentSnapshot document = task.getResult();
                        msgNick = document.getString("usernm");
                    }
                });
                holder.msg_nick.setText(msgNick);
                holder.msg_left.setText(String.valueOf(model.getMsg()));
                holder.msg_right.setVisibility(View.INVISIBLE);
                Log.d(TAG, "status0" );
        }
        }
        @NonNull
        @Override
        public MessageAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType){
            View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_message,parent,false);
            return new MessageAdapter.ViewHolder(v);
        }
    };
    adapter.startListening();
    recyclerView.setAdapter(adapter);
}

我的消息适配器类：

public class MessageAdapter extends RecyclerView.Adapter<MessageAdapter.ViewHolder> {
    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return null;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {

    }

    @Override
    public int getItemCount() {
        return 0;
    }

    public static class ViewHolder extends RecyclerView.ViewHolder {

        public TextView msg_right;
        public ImageView profile_image;
        public TextView msg_left;
        public TextView msg_nick;

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

            msg_right = itemView.findViewById(R.id.msg_right);
            profile_image = itemView.findViewById(R.id.msg_leftavatar);
            msg_left = itemView.findViewById(R.id.msg_left);
            msg_nick = itemView.findViewById(R.id.msg_nick);
        }
    }
}

上下滚动前的聊天状态：

"

然后这样做：

Answer 1

请尝试在else语句的回调监听器中移动设置holder成员的代​​码块。

private void readMessages(){
    Query query = DataRef.collection("rooms").document(roomID).collection("messages").orderBy("timestamp", Query.Direction.ASCENDING);
    FirestoreRecyclerOptions<MessageModel> options = new FirestoreRecyclerOptions.Builder<MessageModel>().setQuery(query, MessageModel.class).build();
    adapter = new FirestoreRecyclerAdapter<MessageModel, MessageAdapter.ViewHolder>(options) {
        @Override
        protected void onBindViewHolder(MessageAdapter.ViewHolder holder, int position, MessageModel model) {
            if (myUid.equals(model.getUid())) {
                Log.d(TAG, "status1");
                holder.msg_right.setText(String.valueOf(model.getMsg()));
                holder.msg_left.setVisibility(View.INVISIBLE);
                holder.profile_image.setVisibility(View.INVISIBLE);
                holder.msg_nick.setVisibility(View.INVISIBLE);
            }
            else
            {
                DataRef.collection("users").document(String.valueOf(model.getUid())).get().addOnCompleteListener(new OnCompleteListener<DocumentSnapshot>() {
                    @Override
                    public void onComplete(@NonNull Task<DocumentSnapshot> task) {
                        DocumentSnapshot document = task.getResult();
                        msgNick = document.getString("usernm");
                        holder.msg_nick.setText(msgNick);
                        holder.msg_left.setText(String.valueOf(model.getMsg()));
                        holder.msg_right.setVisibility(View.INVISIBLE);
                        Log.d(TAG, "status0" );                    }
                });

        }
        }