Android : Listadapter loading downloaded images

Question

I trying to create custom Listadapter using BaseAdapter , in this adapter the images are URLs and the adapter must download every thing then update the view ..

every thing done and work ok but my problem is the I cant move the list view when the images still loading I should wait to finish load every thing then I can move ..

I think the problem happen because the list view return to top index every update because I update on every image done download but I'm not sure because the list freeze so I can't move it to confirm that, or there is some thing else ..

I update listadapter using :

adap.notifyDataSetChanged();

this is all details and I hope any body know how can I fix this problem help me and tell me what is the right way to update the view without problems (return to first index,freeze) ..

Note : no problem with download and I can move the list when images downloading the problem only when loading and update .

Solve :

I checked my code the download function ok and the freeze from update Adapter :

adp.notifyDataSetChanged(); 

it's take a few seconds to update so I Change the update way :

int index = lst.getFirstVisiblePosition();
    View v = lst.getChildAt(0);
    int top = (v == null) ? 0 : v.getTop();
    // ...
   adap.notifyDataSetInvalidated();
    // restore
    lst.setSelectionFromTop(index, top);

Answer 1

try using google volley library it will help you to download faster.

Answer 2

I use this library for async downloading images.

You can examine my code and adapt it for your project.

class WallAdapter extends BaseAdapter {

WallInfo wallInfo;
Activity activity;
LayoutInflater inflater=null;

public WallAdapter(Activity a, WallInfo wallInfo) {
    this.activity = a;
    this.wallInfo = wallInfo;
    inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
}

@Override
public int getCount() {
    return wallInfo.getCount();
}

@Override
public Object getItem(int position) {
    return wallInfo.getItem(position);
}

@Override
public long getItemId(int position) {
    return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
    View vi=convertView;
    if(convertView == null)
        vi = inflater.inflate(R.layout.wall_item, null);

    ImageView imagePost = (ImageView) vi.findViewById(R.id.imagePost);

    WallMessage post = wallInfo.getItem(position);

    if(post.attachments != null && post.attachments.size() != 0) {
        UrlImageViewHelper.setUrlDrawable(imagePost, post.attachments.get(0).photo.src_big);
    } else {
        imagePost.setImageBitmap(null);
    }
    return vi;
}

}