// Create an object for subclass of AsyncTask
GetXMLTask task = new GetXMLTask();
// Execute the task
task.execute(new String[] { "ImageURL" });
//then in Asyntask class assign the image to image view to avoid android.os.NetworkOnMainThreadException
private class GetXMLTask extends AsyncTask<String, Void, Bitmap> {
    @Override
    protected Bitmap doInBackground(String... urls) {
        Bitmap map = null;
        for (String url : urls) {
            map = downloadImage(url);
        }
        return map;
    }
    // Sets the Bitmap returned by doInBackground
    @Override
    protected void onPostExecute(Bitmap result) {
        imageView.setImageBitmap(result);
    }
    // Creates Bitmap from InputStream and returns it
    private Bitmap downloadImage(String url) {
        Bitmap bitmap = null;
        InputStream stream = null;
        BitmapFactory.Options bmOptions = new BitmapFactory.Options();
        bmOptions.inSampleSize = 1;
        try {
            stream = getHttpConnection(url);
            bitmap = BitmapFactory.
                    decodeStream(stream, null, bmOptions);
            stream.close();
        } catch (IOException e1) {
            e1.printStackTrace();
        }
        return bitmap;
    }
    // Makes HttpURLConnection and returns InputStream
    private InputStream getHttpConnection(String urlString)
            throws IOException {
        InputStream stream = null;
        URL url = new URL(urlString);
        URLConnection connection = url.openConnection();
        try {
            HttpURLConnection httpConnection = (HttpURLConnection) connection;
            httpConnection.setRequestMethod("GET");
            httpConnection.connect();
            if (httpConnection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                stream = httpConnection.getInputStream();
            }
        } catch (Exception ex) {
            ex.printStackTrace();
        }
        return stream;
    }
}