android.os.NetworkOnMainThreadException in AsyncTask's doInBackground

Question

Why do I get in an AsyncTask which should a android.os.NetworkOnMainThreadException? I thought that an AsyncTask is the solution to that problem. The exxeption is on line 7.

Answer 1

Best way to download an image and attach it to a ImageView is passing the ImageView as the parameter in your async task and set the URL as a tag of the image view then after downloading the task in the OnPostExecute() set the image to the ImageView look at this example :

public class DownloadImagesTask extends AsyncTask {

ImageView imageView = null;

@Override
protected Bitmap doInBackground(ImageView... imageViews) {
    this.imageView = imageViews[0];
    return download_Image((String)imageView.getTag());
}

@Override
protected void onPostExecute(Bitmap result) {
    imageView.setImageBitmap(result);
}


private Bitmap download_Image(String url) {
    ...
}

And the Usage will be like this

ImageView mChart = (ImageView) findViewById(R.id.imageview);
String URL = "http://www...someImageUrl ...";

mChart.setTag(URL);
new DownloadImageTask.execute(mChart);

The image will be attached automatically when done, for more memory optimization you could use WeakReference.

Good Luck.