离线时Recyclerview不调用onCreateViewHolder答案

【问题标题】：Recyclerview not call onCreateViewHolder when offline离线时Recyclerview不调用onCreateViewHolder
【发布时间】：2018-02-14 16:22:03
【问题描述】：

当我的设备在线时，RecyclerView 适配器按预期工作。离线时，不会调用 onCreateViewHolder。

首先，我知道这一点：Recyclerview not call onCreateViewHolder 这不是问题所在。 getItemCount() 返回一个 >0 的数字，并且我在调用活动中正确设置了适配器和布局管理器的顺序：

mAdapter = new MovieAdapter(this, this, movies, mScreenWidthPx, mIsFavorites);
    mMovieRecyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));
    mMovieRecyclerView.setAdapter(mAdapter);

所以，它似乎与在线/离线状态有关，但我不知道如何。这是适配器：

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

private static final String TAG = MovieAdapter.class.getSimpleName();

private ArrayList<Movie> mMovies;
private Context mContext;
private MovieClickListener mClickListener;
private int mScreenWidthPx;
private boolean mIsFavorite;

public interface MovieClickListener {
    void onMovieClick(Movie movie);
}

public MovieAdapter(Context context, MovieClickListener movieClickListener, ArrayList<Movie> movies, int screenWidthPx, boolean isFavorite) {
    Log.d(TAG,"creating MovieAdapter");
    this.mContext = context;
    this.mMovies = movies;
    this.mClickListener = movieClickListener;
    this.mScreenWidthPx = screenWidthPx;
    this.mIsFavorite = isFavorite;
    Log.d(TAG,"mMovies size constructor:" + mMovies.size());
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    Log.d(TAG,"onCreateViewHolder");
    View view = LayoutInflater.from(mContext).inflate(R.layout.item_movie, parent, false);
    return new ViewHolder(view);
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
    Log.d(TAG,"onBindViewHolder");
    if (mIsFavorite) {
        Log.d(TAG,"loading local image file");
        String fileName = ImageUtils.getMoviePosterFileName(mMovies.get(position).getTitle());
        File imageFile = ImageUtils.getImageFile(mContext,fileName);
        Picasso.with(mContext)
                .load(imageFile)
                .into(holder.mImagePoster);
    }
    else
        {
        Log.d(TAG,"loading remote image file");
        String posterUrl = NetworkUtils.buildMoviePosterUrl(mMovies.get(position).getPosterPath(), mScreenWidthPx);
        Picasso.with(mContext)
                .load(posterUrl)
                .into(holder.mImagePoster);
    }
}

@Override
public int getItemCount() {
    Log.d(TAG,"mMovies size getCount:" + mMovies.size());
    return mMovies.size();
}

public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
    @BindView(R.id.image_movie_poster) ImageView mImagePoster;

    ViewHolder(View itemView) {
        super(itemView);
        Log.d(TAG,"creating ViewHolder");
        ButterKnife.bind(this, itemView);
        itemView.setOnClickListener(this);
    }

    @Override
    public void onClick(View view) {
        int adapterPosition = getAdapterPosition();
        mClickListener.onMovieClick(mMovies.get(adapterPosition));
    }
}
}

【问题讨论】：

您是否为毕加索设置了任何网络政策？

标签： android android-recyclerview android-adapter offline offline-caching

【解决方案1】：

这与网络无关，它告诉我当您的网络状态发生变化时，您传入的名为movies 的数组可能正在从另一个类更改。祝你好运。

【讨论】：

【解决方案2】：

在离线模式下，毕加索库无法下载图像，在这种情况下，图像结果将为空。您可能需要为 Picasso 设置 NetworkPolicy，如下所示：- 如果有网络或不尝试先从缓存下载图像，如果失败则从网络下载。这是代码sn-p：-

Picasso.with(context)
                    .load(Uri.parse(getItem(position).getStoryBigThumbUrl()))
                    .networkPolicy(NetworkPolicy.OFFLINE)
                    .into(holder.storyBigThumb, new Callback() {
                        @Override
                        public void onSuccess() {

                        }

                        @Override
                        public void onError() {
                            // Try again online if cache failed
                            Picasso.with(context)
                                    .load(Uri.parse(getItem(position)
                                            .getStoryBigThumbUrl()))
                            .placeholder(R.drawable.user_placeholder)
                            .error(R.drawable.user_placeholder_error)
                                    .into(holder.storyBigThumb);
                        }
                    });

【讨论】：