Picasso library is not loading images from the server correctly in a listview

Question

I am trying to use RecylerView which Google introduced recently. I have a set of rows there, 7-8 for now, and each row has a image which I am getting from server. For this I am using Picasso library but this is not working for me. I am not sure if I am missing something or configure something.

The screen is correctly showing the default image on each row but doesn't download image from server and I wait more than 5 minutes if slow response from server but that is not the case.

Code

public DemoRecyclerAdapter(List<DemoRowModel> items, int itemLayout, final Context mContext) {
    this.items = items;
    this.itemLayout = itemLayout;
    this.mContext = mContext;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(itemLayout, parent, false);
    return new ViewHolder(v);
}

@Override
public void onBindViewHolder(final ViewHolder holder, int position) {
    DemoRowModel item = items.get(position);

    holder.mDemoNameTextView.setText(item.getDemoName());
    holder.mDemoDateTextView.setText(item.getDemoDate());

    Target mTarget = new Target() {
        @Override
        public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom loadedFrom) {
            holder.mImageView.setImageBitmap(bitmap);
        }

        @Override
        public void onBitmapFailed(Drawable drawable) {
            Logger.d(TAG, "Failed! Bitmap could not downloaded.");
        }

        @Override
        public void onPrepareLoad(Drawable drawable) {
        }
    };

    Picasso.Builder builder = new Picasso.Builder(mContext);
    Picasso picasso = builder.downloader(new OkHttpDownloader(mContext) {
        @Override
        protected HttpURLConnection openConnection(Uri uri) throws IOException {
            HttpURLConnection connection = super.openConnection(uri);
            // fetch the auth value
            SharedPreferences mSharedPreferences = PreferenceManager.getDefaultSharedPreferences(mContext.getApplicationContext());
            connection.setRequestProperty(Constant.HEADER_X_API_KEY, mSharedPreferences.getString(SharedPreferenceKeys.JSESSIONID, ""));
            return connection;
        }
    }).build();

    picasso.load(item.getImagePath()).into(mTarget);

    // here set the value
    holder.itemView.setTag(item);

}

Thanks in advance.

Answer 1

If you are using Target's - they should be strong referenced objects. Create field mTaget in your class and move Target's initialization from onBindViewHolder method.

Edit: hold auth keys in secure place, like keystore. Don't save them in SharedPreferences, it's a bad practice.

Update:

1) create custom Target class

public class CommonImageTarget implements Target {
    private final ImageView imageView;

    public CommonImageTarget(final ImageView imageView) {
        this.imageView = imageView;
    }

    @Override
    public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
        this.imageView.setImageBitmap(bitmap);
    }

    @Override
    public void onBitmapFailed(Drawable errorDrawable) {
        Logger.d(TAG, "Failed! Bitmap could not downloaded.");
    }

    @Override
    public void onPrepareLoad(Drawable placeHolderDrawable) {
    }
}

2) create custom ImageView

public class ImageViewWithTarget extends ImageView{
    /**
     * Required for Bitmap loading using Picasso. Picasso uses weak references in into() method and Target's are garbage collected, save them in object.
     */
    private Target target;

    public ImageViewWithTarget(Context context) {
        super(context);
    }

    public ImageViewWithTarget(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public ImageViewWithTarget(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public Target getTarget() {
        return target;
    }

    public void setTarget(Target target) {
        this.target = target;
    }
}

3) when you initialize your imageView in viewHolder, set custom Target in it

viewHolder.mImageView.setTarget(new CommonImageTarget(viewHolder.mImageView));

4) update ViewHolder class

public class ViewHolder{
       ...
       private ImageViewWithTarget mImageView;
   }

5) replace ImageView with ImageViewWithTarget in your layout

6) update onBindViewHolder method

picasso.load(item.getImagePath()).into(viewHolder.mImageView.getTarget());

Now every ImageView will hold own Target object, and Target isn't garbage collected.

Another way: hold Target object in ViewHolder.