Picasso loads into wrong imageview when using view

问题:

I'm trying to use the Picasso library to load external images into rows in a ListView. I have a custom ArrayAdapter as follows:

public class RevisedBusinessesAdapter extends ArrayAdapter<HashMap<String, String>> {

    Context context;
    int layoutResourceId;
    ArrayList<HashMap<String, String>> data = null;

    public RevisedBusinessesAdapter(Context context, int layoutResourceId,  ArrayList<HashMap<String, String>> data) {
        super(context, layoutResourceId, data);
        this.layoutResourceId = layoutResourceId;
        this.context = context;
        this.data = data;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View row = convertView;
        RevisedBusinessHolder holder = null;

        if (row == null) {
            LayoutInflater inflater = ((Activity) context).getLayoutInflater();
            row = inflater.inflate(layoutResourceId, parent, false);
            holder = new RevisedBusinessHolder();
            holder.ivLogo = (ImageView) row.findViewById(R.id.ivBusinessLogo);
            row.setTag(holder);
        } else {
            holder = (RevisedBusinessHolder) row.getTag();
        }

        HashMap<String, String> business = data.get(position);

        String strLogoURL = business.get("logoURL");
        if (null != strLogoURL && !"".equals(strLogoURL)) {
            Picasso.with(this.context).load(strLogoURL).into(holder.ivLogo);        
        }

        return row;
    }

    static class RevisedBusinessHolder {
        ImageView ivLogo;
    }
}

where logoURL is an URL for a remotely located image; if not supplied, ivBusinessLogo has a local src set, and that is shown instead. When I scroll quickly, Picasso loads the image into the wrong ImageView and I end up with multiple copies of it in the list.

The answer to this question suggests adding

Picasso.with(context).cancelRequest(holder.ivLogo);

before the existing Picasso call, but that doesn't make any difference. If I remove the row == null check and always create a new view, it appears to work fine. In the full version of this, though, there are also four textviews and five other images (small icons loaded from local resources, not via Picasso) that need to be updated in each getView.

Is there a way to make this work with the View Holder pattern the Android documentation recommends?

回答1:

You should always call Picasso, even if your URL is null. This way it knows that the image view was recycled.

Delete this if statement:

if (null != strLogoURL && !"".equals(strLogoURL)) {

You should also consider using a placeholder image or an error image so that something will be displayed when there is no URL.

If you insist on keeping the if statement (but you shouldn't!), you need to tell Picasso that the image view was recycled by calling cancelRequest:

Picasso.with(this.context).cancelRequest(holder.ivLogo);

回答2:

The default src drawable set in the layout.xml (on ImageView) is beeing override by the last cached dowload image if the current item doesnt have a image to be download from the url.

You must manually set the default drawable for itens that dont have a image atribute:

try {
     Picasso.with(activity.getApplicationContext()).load(customer.getImage().getPath()).placeholder(R.drawable.image_placeholder)
                .error(R.drawable.image_placeholder).into(imageView);
    }
catch (Exception e) {
       imageView.setImageResource(R.drawable.default_customer_icon);
       // this set the default img source if the path provided in .load is null or some error happened on download.
    }

回答3:

I have same problem and fixed it. Please consider about param convertView in getView method

convertView is old view to reuse, if possible. Note: You should check that this view is non-null and of an appropriate type before using. If it is not possible to convert this view to display the correct data, this method can create a new view.

When you use holder, Picasso will load image to the imageview of an row and all reuse of it. That why you see duplicate image. And in my opinion you should load your image while first time row view created. Try to change your code to

if (row == null) {
    LayoutInflater inflater = ((Activity) context).getLayoutInflater();
    row = inflater.inflate(layoutResourceId, parent, false);
    holder = new RevisedBusinessHolder();
    ImageVIew ivLogo = (ImageView) row.findViewById(R.id.ivBusinessLogo);
    Picasso.with(this.context).load("Your Image URL").into(holder.ivLogo);
    row.setTag(holder);
}

回答4:

Add an else statement after the Picasso.with().load().into() statement. Add else holder.ivLogo.setImageBitmap(null);. Or use a placeholder bitmap.

Having seen the solution of Octa George it is better to always execute holder.ivLogo.setImageBitmap(placeholderbitmap); before the call to Picasso. Otherwise when Picasso 'takes his time' you would first see a wrong recycled image.