帮忙看下java这3行代码的作用是干嘛的

Question

Map> RoomImagesMap = Maps.newHashMap();
RoomImagesMap.put(imageInfo.getRefId(), Lists.newArrayList());

 RoomImagesMap.get(imageModel.getRefId()).add(imageModel);

Answer 1

 Map<Long, List<ImageModel>> RoomImagesMap = Maps.newHashMap();
定义了一个叫做RoomImagesMap，以Long为键，ImageModel的列表为值的Map
   RoomImagesMap.put(imageInfo.getRefId(), Lists.<ImageModel>newArrayList());
         将imageInfo的Refid作为键，而一个新的列表作为值插入这个Map
     RoomImagesMap.get(imageModel.getRefId()).add(imageModel);
        将mageModel插入刚才插入的，以Refid为键的那个Map条目的空白列表中