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POLazy load of images on ListView with AsyncTask launched on the getView (adapter)
 

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  1. POLazy load of images on ListView with AsyncTask launched on the getView (adapter)
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    <p>I have a ListView with items that have some text and one ImageView. I would like to use and AsyncTask in order to load the ImageView (lazy load). I know there are some libraries in order to do that. The problem is that is not possible to get the images just with a URL, like</p> <pre><code>imageLoader.displayImage(imageUri, imageView); </code></pre> <p>because I need to add some headers to the HTTP GET (authentication token). So inside the getView() of the adapter I have to launch an AsyncTask that will download the image as Bitmap and show it on the ImageView.</p> <p>Is there any code example? I tried to pass the ImageView to the AsyncTask in the constructor of the AsyncTask, download the Bitmap and assign it to the ImageView on the onPostExecute, something like this:</p> <pre><code>public class LoadImageTask extends AsyncTask&lt;String, Void, Bitmap&gt;{ private ImageView mImage; private Context mContext; private String imageId; private Throwable mThrown = null; public LoadImageTask(ImageView ivImage, Context context) { mImage = ivImage; mContext = context; } @Override protected Bitmap doInBackground(String... params) { imageId = params[0]; // Build request and request token .... //Process the response try { HttpEntity entity = mHttpResponse.getEntity(); InputStream inputStream = entity.getContent(); BufferedInputStream bis = new BufferedInputStream(inputStream); Bitmap bm = BitmapFactory.decodeStream(bis); bis.close(); inputStream.close(); return bm; } catch (IOException e) { mThrown = e; RestClient.consumeContent(mHttpResponse); return null; } } RestClient.consumeContent(mHttpResponse); return null; } @Override protected void onPostExecute(Bitmap bm) { mImage.setImageBitmap(bm); } </code></pre> <p>}</p> <pre><code>public View getView(int position, View convertView, ViewGroup parent) { LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE); View rowView = inflater.inflate(R.layout.news_item, null); TextView tvNewsTitle = (TextView) rowView.findViewById(R.id.tvNewsTitle); TextView tvUpdateDate = (TextView) rowView.findViewById(R.id.tvUpdateDate); ImageView ivImage = (ImageView) rowView.findViewById(R.id.ivNewsThumbnail); News news = mNewsList.get(position); tvNewsTitle.setText(news.getTitle()); tvUpdateDate.setText(news.getLastUpdate()); new LoadImageTask(ivImage, mContext).execute(news.getImageThumbnail()); return rowView; } </code></pre> <p>But looks like it's always updating only the fist element of the ListView. </p> <p>Is there any example code?</p>
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    1. USsteve_patrick
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    1. COI wrote something that does exactly this last year - I will see if I can find it. Basically, you need to ensure that you're actually finishing your web service calls.
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      1. POLazy load of images on ListView with AsyncTask launched on the getView (adapter)
      1. USCodeman
    2. COdid you checked if null reached for other images?
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      1. UShasan
 

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