ViewModel 实现 Room 缓存观察分页列表，recyclerView 中没有显示数据

如何解决ViewModel 实现 Room 缓存观察分页列表，recyclerView 中没有显示数据

我正在尝试在我的应用程序中的 recyclerView 中实现本地房间缓存。 这是视图模型类：

     public class FeedDetailViewModel extends AbsViewModel<Comment> {
        private long itemId;
        private volatile boolean witchCache = true;
        private MutableLiveData<PagedList<Comment>> cacheLiveData = new MutableLiveData<>();
        private AtomicBoolean loadAfter = new AtomicBoolean(false);
    
        @Override
        public DataSource createDataSource() { return new CommentDataSource();};
    
        public MutableLiveData<PagedList<Comment>> getcacheLiveData() {
            return cacheLiveData;
        }
    
    ...
    
   private void loadData(Integer key,int requestedLoadSize,ItemKeyedDataSource.LoadCallback<Comment> 
   callback) {
            if (key > 0) {
                loadAfter.set(true);
            }

      Request request= ApiService.get("/comment/queryFeedComments")
                            .addParam("id",key)
                            .addParam("itemId",itemId)
                            .addParam("userId",UserManager.get().getUserId())
                            .addParam("pageCount",requestedLoadSize)
                            .responseType(new TypeReference<ArrayList<Comment>>() {
                            }.getType());
        
                    if (witchCache) {
                        request.cacheStrategy(Request.CACHE_ONLY);
                        request.execute(new JsonCallback<List<Comment>>() {
                            @Override
                            public void onCacheSuccess(ApiResponse<List<Comment>> response) {
                                Log.e("loadData","onCacheSuccess: ");
                                MutablePageKeyedDataSource dataSource = new MutablePageKeyedDataSource<Comment>();
                                dataSource.data.addAll(response.body);//**without network,data retrieved from cache successfully**
                                PagedList pagedList = dataSource.buildNewPagedList(config);
                                cacheLiveData.postValue(pagedList);
                            }
                        });
                    }
        
                    try {
                        Request netRequest = witchCache ? request.clone() : request;
                        netRequest.cacheStrategy(key == 0 ? Request.NET_CACHE : Request.NET_ONLY);
                        ApiResponse<List<Comment>> response = netRequest.execute();
                        List<Comment> data = response.body == null ? Collections.emptyList() : response.body;
                        callback.onResult(data);
        
                        if (key > 0) {
                            ((MutableLiveData) getBoundaryPageData()).postValue(data.size() > 0);
                            loadAfter.set(false);
                        }
                    } catch (CloneNotSupportedException e) {
                        e.printStackTrace();
                    }
        
                };

       }

...

}

这是初始化适配器的代码，它扩展了 AbsPagedListAdapter：

listAdapter = new FeedCommentAdapter(mActivity) {
            @Override
            public void onCurrentListChanged(@Nullable PagedList<Comment> previousList,@Nullable PagedList<Comment> currentList) {
                boolean empty = currentList.size() <= 0;
                handleEmpty(!empty);
            }
        };
        mRecyclerView.setAdapter(listAdapter);

这是观察分页列表变化的代码：

viewModel.setItemId(mFeed.itemId);

viewModel.getcacheLiveData().observe(mActivity,new Observer< PagedList<Comment>>() { 
            @Override
            public void onChanged(PagedList<Comment> comments) {
                listAdapter.submitList(comments); 
                handleEmpty(comments.size() > 0);
            }

        });

在观察中使用 getPagedData() 而不是 getcacheLiveData() 可以处理在网络可用的 recyclerView 中显示的数据。使用getcacheLiveData()，recyclerView中什么也没有出现，但是dataSource似乎成功接收到了从Room缓存中检索到的数据。

在我看来，代码观察分页列表的变化有问题，但我花了一些时间，因为我基本上处于初学者水平，无法弄清楚。如果有人能提供帮助，我们将不胜感激。