code: public static synchronized void initialize(Context context) {
          if (executor == null) {
              executor = (ThreadPoolExecutor) Executors.newFixedThreadPool(DEFAULT_POOL_SIZE);
          }
          if (imageCache == null) {
              imageCache = new ImageCache(25, expirationInMinutes, DEFAULT_POOL_SIZE);
              imageCache.enableDiskCache(context, ImageCache.DISK_CACHE_SDCARD);
          }
      }
docs: This method must be called before any other method is invoked on this class. Please note that
  when using ImageLoader as part of {@link WebImageView} or {@link WebGalleryAdapter}, then
  there is no need to call this method, since those classes will already do that for you. This
  method is idempotent. You may call it multiple times without any side effects.
  
  @param context the current context