即使在notifyDataSetChanged（）之后，Firebase RecycleView适配器也不会更新

Question

我已经为特定的Firebase数据库参考注册了一个侦听器。 数据“更改”后，它将显示一条敬酒消息，应将chatMessage添加到列表中，并在回收视图中显示该项目。 但是，仅显示Toast消息，但该项目未添加到回收视图。 我相信这是由RecycleView适配器的问题引起的，但是我无法查明位置。

public void getMessageByMessageUUID(final MessageAdapter messageAdapter, final String chatUUID, final String messageUUID) {
    MESSAGE_REFERENCE.child(chatUUID).child(messageUUID).addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            ChatMessage message = dataSnapshot.getValue(ChatMessage.class);
            Toast.makeText(getApplicationContext(),
                    "Welcome " + chatUUID + " " + message.getMessageText(),
                    Toast.LENGTH_LONG)
                    .show();
            messageAdapter.addMessage(message);

            messageAdapter.notifyDataSetChanged();
        }

转接器类别

private ArrayList<ChatMessage> messages = new ArrayList<ChatMessage>();
protected Context context;

public MessageAdapter(final String chatUUID, DatabaseReference databaseReference) {
    databaseReference.addChildEventListener(new ChildEventListener()...);
}

public void addMessage(ChatMessage chatMessage) {
    messages.add(chatMessage);

    notifyDataSetChanged();
}

@Override
public MessageHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    Context context = parent.getContext();
    LayoutInflater inflater = LayoutInflater.from(context);

    MessageHolder viewHolder = null;
    View layoutView = LayoutInflater.from(parent.getContext()).inflate(R.layout.messages, parent, false);
    viewHolder = new MessageHolder(layoutView, messages);

    return viewHolder;
}

@Override
public void onBindViewHolder(MessageHolder holder, int position) {
    holder.messageImage.setImageResource(R.drawable.user_pacific);
    holder.messageText.setText(messages.get(position).getMessageText());
}

@Override
public int getItemCount() {
    return this.messages.size();
}

@Override
public void onAttachedToRecyclerView(RecyclerView recyclerView) {
    super.onAttachedToRecyclerView(recyclerView);
}

Answer 1

问题不在于firebase代码或适配器，而在于LinearLayoutManager。 我相信代码是在屏幕外添加的。 我通过改变解决了这个问题

LinearLayoutManager manager = new LinearLayoutManager(this);

至

LinearLayoutManager manager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);