public void DisplayImage(String productid, Activity activity, ImageView imageView) {
   imageViews.put(imageView, productid);
   Bitmap bitmap = memoryCache.get(productid);
   if (bitmap != null) {
     imageView.setImageBitmap(bitmap);
   } else {
     queuePhoto(productid, activity, imageView);
     imageView.setImageBitmap(null);
   }
 }
 public void clearCache() {
   memoryCache.clear();
   fileCache.clear();
 }