RecyclerView：未附加适配器；跳过布局

Question

我一直在stackoverflow和这篇博文上阅读不同的答案，并试图实现它们的解决方案，但我仍然得到错误：

public class ProfileFragment extends Fragment {

private ModelUser user;

private View view;
private RecyclerView gridView;
private ProfilePhotoRecyclerViewAdapter adapter;
private List<ModelAttachment> photoList = new ArrayList<ModelAttachment>();

public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

    view = inflater.inflate(R.layout.fragment_profile, container, false);

    initializeRecyclerView();

    //Get extra info for user
    QueryAPI query = new QueryAPI();
    query.userExtra(user, new QueryAPI.ApiResponse<ModelUser>() {
        @Override
        public void onCompletion(ModelUser result) {
            user = result;
                photoList.clear();
                photoList.addAll(0,user.getPhotos());

                adapter.notifyDataSetChanged();

            }
        });

     return view;

}

}

void initializeRecyclerView() {
        gridView = (RecyclerView) view.findViewById(R.id.grid_view);
        StaggeredGridLayoutManager gridLayoutManager = new StaggeredGridLayoutManager(3,StaggeredGridLayoutManager.HORIZONTAL );
        adapter = new ProfilePhotoRecyclerViewAdapter(getActivity(), photoList);
        gridView.setAdapter(adapter);
        gridView.setLayoutManager(gridLayoutManager);
        gridView.setHasFixedSize(true);
    }

片段中的布局：

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

和项目的布局：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">

<com.android.volley.toolbox.NetworkImageView
    android:id="@+id/imageView"
    android:contentDescription="@string/image_description"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:scaleType="centerCrop"
    android:adjustViewBounds="true" />

 </LinearLayout>

我做错了什么？

编辑：以下是适配器：

public class ProfilePhotoRecyclerViewAdapter extends  RecyclerView.Adapter<ProfilePhotoRecyclerViewAdapter.ViewHolder> {

    private LayoutInflater inflater;
    private List<ModelAttachment> photos; //data
    private Activity listContext;
    private int listRowLayoutId;
    ImageLoader imageLoader = AppController.getInstance().getImageLoader();


    public ProfilePhotoRecyclerViewAdapter(Activity context, List<ModelAttachment> objs) {
        photos = objs;
        listContext = context;
        this.notifyDataSetChanged();
    }

    @Override
    public ProfilePhotoRecyclerViewAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int i) {

        View itemView = LayoutInflater.from(listContext).inflate(R.layout.profile_photogrid_item, parent, false);

        return new ProfilePhotoRecyclerViewAdapter.ViewHolder(itemView);
    }

    @Override
    public void onBindViewHolder(ProfilePhotoRecyclerViewAdapter.ViewHolder viewHolder, int i) {

        ModelAttachment photo = photos.get(i);
        viewHolder.imageView.setImageUrl(photo.getUrl(), imageLoader);
    }

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


    public static class ViewHolder extends RecyclerView.ViewHolder {

        ModelAttachment photo;
        public NetworkImageView imageView;

        public ViewHolder(View itemView) {
            super(itemView);
            this.imageView = (NetworkImageView) itemView.findViewById(R.id.imageView);
        }
    }
}