Question

我正在使用带有聊天消息列表的RcyclerView适配器。

每次添加到firebase的消息我都使用'onChildAdded'监听器来更新适配器列表。我还想通过添加更改颜色动画的背景来更新某些消息。问题是我不知道如何访问我的适配器中的特定消息的位置。

这是我的chatListadapter：

class ChatListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {
private List<ChatMessage> msgList;
private static final int VIEW_TYPE_MESSAGE_LEFT = 1;
private static final int VIEW_TYPE_MESSAGE_RIGHT = 2;
private DataReferences DB;

ChatListAdapter(List<ChatMessage> msgList) {
    this.msgList = msgList;
}

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

@Override
public int getItemViewType(int position) {
    DB = DataReferences.getInstance();
    ChatMessage msg = msgList.get(position);
    if (!msg.uid.equals(DB.uid)) {
            return VIEW_TYPE_MESSAGE_LEFT;
        }
    } else
        return VIEW_TYPE_MESSAGE_RIGHT;
}



@Override
public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View view;

    if (viewType == VIEW_TYPE_MESSAGE_LEFT) {
        view = LayoutInflater.from(parent.getContext()).inflate(R.layout.message_received, parent, false);
        return new LeftViewHolder(view);
    } else {
        view = LayoutInflater.from(parent.getContext()).inflate(R.layout.message_sent, parent, false);
        return new RightViewHolder(view);
    }

}

@Override
public void onBindViewHolder(RecyclerView.ViewHolder holder, final int 
 position) {
    ChatMessage msg = msgList.get(position);
    if (msg.critic)
        switch (holder.getItemViewType()) {
            case VIEW_TYPE_MESSAGE_LEFT:
                ((LeftViewHolder) holder).bind(msg);
                break;
            case VIEW_TYPE_MESSAGE_RIGHT:
                ((RightViewHolder) holder).bind(msg);
                break;
        }

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

private class LeftViewHolder extends RecyclerView.ViewHolder {
    TextView messageText, timeText, nameText;
    public LeftViewHolder(View itemView) {
        super(itemView);
        timeText = (TextView) itemView.findViewById(R.id.text_message_time);
        nameText = (TextView) itemView.findViewById(R.id.text_message_name);
        messageText = (TextView) 
       itemView.findViewById(R.id.text_message_body);
    }

    void bind(ChatMessage message) {
        messageText.setText(message.getMsg());
        timeText.setText(message.getTime());
        nameText.setText(message.UserName);
    }
}

private class RightViewHolder extends RecyclerView.ViewHolder {
    TextView messageText, timeText;

    public RightViewHolder(View itemView) {
        super(itemView);
        timeText = (TextView) itemView.findViewById(R.id.text_message_time);
        messageText = (TextView) 
          itemView.findViewById(R.id.text_message_body);
    }
    void bind(ChatMessage message) {
        messageText.setText(message.getMsg());
        timeText.setText(message.getTime());
    }
}

}

Answer 1

我建议你使用FirebaseRecyclerAdapter FirebaseUI库（https://github.com/firebase/FirebaseUI-Android/blob/master/database/README.md）中的RecyclerView。它使populateViewHolder中的处理数据变得更容易。

使适配器更新特定项目。在FirebaseRecyclerAdapter的{{1}}中，您可以执行以下操作（假设您要在阅读邮件后更改邮件背景）

 override fun populateViewHolder(viewHolder: FieldViewHolder?, model: Message, position: Int) {
                if(model.isRead) {
                    viewholder.updateBackground()
                }
        }

如果您使用普通RecyclerView，可能需要付出一些努力才能找到具体位置并相应地更新用户界面。

希望有所帮助。

在RecyclerView Adapter中更新带动画的项目

1 个答案: