Firestore 回收器適配器 - 滾動后消失的項目

Question

我正在嘗試為我的項目創建聊天服務，為此，我將消息存儲在從服務器獲取的 Firestore 數據庫中，並分配將發件人 ID 與當前用戶 ID 進行比較的文本。 當我開始活動時，消息會正確顯示，但是當我向下滾動時，我的消息會停止顯示，或者其他用戶的消息會消失，這取決於是否打開了聊天帳戶。

我似乎無法弄清楚為什么會發生這種情況。

我的 readMessages function：

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);
}

我的消息適配器 class：

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);
        }
    }
}

上下滾動前聊天的 State：

"

這樣做之后：

Answer 1

請嘗試在else語句的回調監聽器中移動設置holder成員的代碼塊。

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" );                    }
                });

        }
        }