ViewHolders for ListViews with different item layouts

Question

I have ListView with 2 different types of layout: one with image and another without image. I try to do something like this. I override getView of BaseAdapter:

public View getView(int position, View convertView, ViewGroup parent) {
        Map<String, String> item = mData.get(position);
        if(item.get("image_location").equals("") == true){
            ViewHolderWithoutImage holder = new ViewHolderWithoutImage();
            if(convertView == null){
                convertView = mInflater.inflate(R.layout.row_without_image, null);
                holder.title = (TextView)convertView.findViewById(R.id.title);
                holder.firstParagraph = (TextView)convertView.findViewById(R.id.first_paragraph);
                convertView.setTag(holder);
            }else{
                holder = (ViewHolderWithoutImage)convertView.getTag();
            }
            holder.title.setText(mData.get(position).get("title").toString());
            holder.firstParagraph.setText(item.get("first_paragraph").toString());

        }else{
            ViewHolderWithImage holder = new ViewHolderWithImage();
            Bitmap bm = null;
            if(convertView == null){
                convertView = mInflater.inflate(R.layout.row_with_image, null);
                holder.title = (TextView)convertView.findViewById(R.id.title_image);
                holder.firstParagraph = (TextView)convertView.findViewById(R.id.first_paragraph_image);
                holder.image = (ImageView)convertView.findViewById(R.id.image);
                convertView.setTag(holder);
            }else{
                holder = (ViewHolderWithImage)convertView.getTag();
            }

            holder.title.setText(mData.get(position).get("title").toString());
            holder.firstParagraph.setText(item.get("first_paragraph").toString());
            String location = imageBaseUrl + item.get("image_location");
            bm = downloadImage(location);
            holder.image.setImageBitmap(bm);
        }
        return convertView;
    }

My ViewHolders classes:

static class ViewHolderWithImage {
        TextView title;
        TextView firstParagraph;
        ImageView image;
    }

    static class ViewHolderWithoutImage {
        TextView title;
        TextView firstParagraph;
    }

It works without the second part, but crashes when it going to

holder = (ViewHolderWithImage)convertView.getTag();

in part when item.get("image_location").equals("") != true with java.lang.reflect.InvocationTargetException. Any ideas how can I fix that?

Predecessor

Try using getCause() or getTargetException() (see here: download.oracle.com/javase/1.4.2/docs/api/java/lang/reflect/…) to get more info regarding the exception. – Levison

Answer 1

I think it's happens because convertView's tag holds ViewHolder with different type. Try to check convertView type:

if(item.get("image_location").equals("") == true){
    ...
    if(convertView == null || !(convertView.getTag() instanceof ViewHolderWithoutImage)){
    ...
}else{
    ...
    if(convertView == null || !(convertView.getTag() instanceof ViewHolderWithImage)){
        convertView = mInflater.inflate(R.layout.row_with_image, null);
        ...

P.S. It's better to use system methods for handling different layouts (override getItemViewType()). There is good article on this topic.

Davidson

The last piece of code of the article is not correct. He's not managing this case for example : convertView != null and currently instanciated to R.layout.item1 but current positon need R.layout.item2 – Mefford

Answer 2

You should override getItemViewType() and getViewTypeCount() on your Adapter, returning a distinct number for each row type, like 0 for ViewHolderWithoutImage and 1 for ViewHolderWithImage. This way, getView() could resolve correctly which view to instantiate.

Numbles