Question

I am gathering data from youtube’s gdata API and would like to use the video’s thumbnail. I already have the urls for each of the thumbnails, however I am not able to get the images to show up in my listview. The bitmap is currently not returning null, however I am not able to call the imageview.setImageBitmap(bitmap) method with my current implementation (that I know of?). Please help if you know of a better way to do this! Thanks

public class ResultListActivity extends ListActivity {

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    String searchquery = null;
    Intent starter = getIntent();
    Bundle extras = starter.getExtras();
    if (extras != null) {
        searchquery = extras.getString("search");
    }        
    final String URL = "http://gdata.youtube.com/feeds/api/videos?max-results=5&alt=json&author=user&q=" + searchquery;
    final ArrayList<HashMap<String, ?>> data = new ArrayList<HashMap<String, ?>>();
    final QueryYoutube query;       

    query = new QueryYoutube();
    boolean success = query.searchYoutube(URL); 

    if (success == false) {
        Toast.makeText(this, "Sorry, no matching results found.", Toast.LENGTH_SHORT).show();
        Intent intent = new Intent(ResultListActivity.this, YoutubeActivity.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
        startActivity(intent);
        finish();
    } 

    int size = query.getNumberResults();
    HashMap<String, Object> row  = new HashMap<String, Object>();

    for (int i=0; i<size; i++) {
        Bitmap bitmap = null;
        Drawable d = null;          
        try {                   
            bitmap = BitmapFactory.decodeStream((InputStream)new URL(query.getThumbnail(i)).getContent());
            bitmap.setDensity(Bitmap.DENSITY_NONE);
            d = new BitmapDrawable(bitmap);
        } catch (MalformedURLException e) {
          e.printStackTrace();
        } catch (IOException e) {
          e.printStackTrace();
        }

        row  = new HashMap<String, Object>();
        row.put("Thumbnail", d);            
        row.put("Title", query.getTitle(i));
        row.put("Description", query.getDescription(i));
        data.add(row);
    }

    SimpleAdapter adapter = new SimpleAdapter(this, data, R.layout.row,
              new String[] {"Thumbnail","Title","Description"},
              new int[] {R.id.thumb, R.id.title, R.id.description});
    setListAdapter(adapter);

    ListView lv = getListView();
    lv.setTextFilterEnabled(true);

    lv.setOnItemClickListener(new OnItemClickListener() {

        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            Intent lVideoIntent = new Intent(null, Uri.parse("ytv://"+query.getVideoID(position)), 
                   ResultListActivity.this, OpenYouTubePlayerActivity.class);
            startActivity(lVideoIntent);               
        }
    });

}
}

Answer 1

The way I would recommend doing this is that you should extend the ArrayAdapter class then in the getView method you fire off an AsyncTask to download the thumbnail in thread outside of the UI thread, then set the bitmap to the imageview in onPostExecute.

You should use something like HttpUrlConnection to get the InputStream for the image to decode into a Bitmap. If you are unsure about the dimensions of the Bitmap it is important that you check the size of the image before you actually create a Bitmap object that causes an OutOfMemoryError so beforehand set BitmapFactory.Options inJustDecodeBounds to true and then get the dimensions of the image then choose a sufficient inSampleSize and decode again to retrieve a Bitmap that is not too large.

You should also have some sort of Bitmap cache so that you don’t have to always retrieve from the web.