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[英]Does notifydatasetchanged call onCreateViewHolder when using RecyclerView
[英]Recyclerview not call onCreateViewHolder when offline
當我的設備在線時,RecyclerView適配器可以按預期工作。 脫機時,不會調用onCreateViewHolder。
首先,我知道這一點: Recyclerview不調用onCreateViewHolder ,這不是問題。 getItemCount()返回一個大於0的數字,並且我在調用活動中正確設置了適配器和布局管理器的順序:
mAdapter = new MovieAdapter(this, this, movies, mScreenWidthPx, mIsFavorites);
mMovieRecyclerView.setLayoutManager(new GridLayoutManager(this, numberOfColumns));
mMovieRecyclerView.setAdapter(mAdapter);
因此,它似乎與在線/離線狀態有關,但我不知道如何操作。 這是適配器:
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));
}
}
}
這與網絡無關,網絡告訴我,當網絡狀態更改時,傳入的稱為movies
數組可能已從另一個類更改。 祝好運。
在離線模式下,畢加索庫無法下載圖像,在這種情況下,圖像結果將為空。 您可能需要為Picasso設置NetworkPolicy,如下所示:-如果有網絡或不存在,請嘗試首先從緩存下載圖像,如果失敗,則從網絡下載。 這是代碼段:
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);
}
});
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