支持RecyclerView直到被触摸才显示任何内容 [英] Support RecyclerView doesn't show anything until touched

问题描述

我在我的应用程序中使用了支持RecyclerView的软件，我看到了最奇怪的事情.在我触摸滚动之前，它不会显示任何项目.然后，突然间，RecyclerView会自行填充.我已经验证了支持适配器的列表是否已填充，并且在触摸事件之前永远不会调用onCreatViewHolder和onBindViewHolder.

I'm using the support RecyclerView in my app, and I see the most bizarre thing. It doesn't display any items until I touch to scroll. Then, all of a sudden, the RecyclerView populates itself. I have verified that the list backing the adapter is populated, and that onCreatViewHolder and onBindViewHolder are never called until a touch event.

这是我设置recyclerview的方法:

Here's how I set up the recyclerview:

    @Override
    public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
        Drawable divider = new ColorDrawable(ProfileInfo.getCurrentProfileColor());
        mInboxList.addItemDecoration(new DividerItemDecoration(getActivity(), divider, false));
        mInboxList.setLayoutManager(new LinearLayoutManager(getActivity(), LinearLayoutManager.VERTICAL, false));
        mInboxList.setAdapter(new InboxAdapter(getActivity(), new ArrayList<Conversation>()));
        new AsyncTask<Void, Void, List<Conversation>{

              public List<Conversation> doInBackground(...){
                   //load the conversations
                   return conversations;
              }

              public void onPostExecute(List<Conversation> conversations){
                   ((InboxAdapter) mInboxList.getAdapter()).clear(false);
                   ((InboxAdapter) mInboxList.getAdapter()).addAll(conversations);

              }

        }.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
     }

这是我的适配器的要点:

Here's a gist of my adapter:

public class InboxAdapter extends RecyclerView.Adapter<InboxAdapter.ViewHolder> {
    List<Conversation> mConversations; //initialized in contructor

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View v = mInflater.inflate(R.layout.inbox_item, parent, false);
        ViewHolder holder = new ViewHolder(v);
        Log.d(LOG_TAG, "oncreateviewholder : " + viewType); //never called when I first bind the adapter
        return holder;
    }

    @Override
    public void onBindViewHolder(final ViewHolder holder, int position) {
        final Conversation item = mConversations.get(position);
        Log.d(LOG_TAG, "binding " + position);
        ...
    }

    @Override
    public int getItemCount() {
        Log.d(LOG_TAG, "item count: " + mConversations.size());
        return mConversations.size();
    }

    /**
     * Empties out the whole and optionally notifies
     */
    public void clear(boolean notify) {
        mConversations.clear();
        if (notify) {
            notifyDataSetChanged();
        }
    }

    public void addAll(List<Conversation> conversations) {
        mConversations.addAll(conversations);
        notifyDataSetChanged();
    }


}

这是布局文件:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                xmlns:app="http://schemas.android.com/apk/res-auto"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:paddingTop="?attr/actionBarSize">


    <android.support.v7.widget.RecyclerView
        android:id="@+id/lv_inbox"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        ></android.support.v7.widget.RecyclerView>
</RelativeLayout>

我正在使用在版本4.4.4的Moto X上运行的recyclerview-v7:21.0.3.

I'm using recyclerview-v7:21.0.3 running on a Moto X with version 4.4.4.

onPostExecute末尾的平滑滚动似乎可以解决该问题:

if (mInboxList.getAdapter().getItemCount() > 0) {
    mInboxList.smoothScrollToPosition(0);
}

推荐答案

如果其他任何人使用RxJava和Retrofit遇到此问题，则可以通过在预订之前将.observeOn(AndroidSchedulers.mainThread())运算符添加到我的方法链中来解决此问题.我已经阅读过默认情况下会对此进行处理，因此没有明确的必要，但我想没有.希望这会有所帮助.

If anyone else is having this issue using RxJava and Retrofit, I solved this issue by adding the .observeOn(AndroidSchedulers.mainThread()) operator into my method chain before subscribing. I had read this was taken care of by default, and thus not explicitly necessary, but I guess not. Hope this helps.

示例:

public void loadPhotos() {
    mTestPhotoService.mServiceAPI.getPhotos()
                                 .subscribeOn(Schedulers.io())
                                 .observeOn(AndroidSchedulers.mainThread())
                                 .subscribe(photoList -> mRecyclerActivity.OnPhotosLoaded(photoList));
}

这篇关于支持RecyclerView直到被触摸才显示任何内容的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！