firebase的java读回执功能

Question

当用户打开ChatActivity时，我想更改数据库中每条消息的seen值。这是我的数据库结构

当消息被加载到ChatActivity或消息适配器中时，我不知道在什么位置执行此操作

这是MessageAdapter

void bind(Messages message) {

            String user_id = message.getFrom();
            String message_type = message.getType();

            //  what is the right value to get for this task
            String seen = message.getKey();  // this or 

            boolean seen2 = message.isSeen(); // this


            if (message_type.equals("text")) {


                messageText.setText(message.getMessage());
                timeText.setText(DateUtils.formatDateTime(message.getTime()));
                mSentImage.setVisibility(View.INVISIBLE);
            }else {
                messageText.setVisibility(View.INVISIBLE);
                Picasso.with(mSentImage.getContext()).load(message.getMessage()).into(mSentImage);