As in the official Google docs:

https://developers.google.com/admob/android/banner

which are as always incomplete, I try to use this code:

private AdSize getAdSize() {
  // Determine the screen width (less decorations) to use for the ad width.
  Display display = getWindowManager().getDefaultDisplay();
  DisplayMetrics outMetrics = new DisplayMetrics();
  display.getMetrics(outMetrics);

  float density = outMetrics.density;

  float adWidthPixels = adContainerView.getWidth();

  // If the ad hasn't been laid out, default to the full screen width.
  if (adWidthPixels == 0) {
    adWidthPixels = outMetrics.widthPixels;
  }

  int adWidth = (int) (adWidthPixels / density);
  return AdSize.getCurrentOrientationAnchoredAdaptiveBannerAdSize(this, adWidth);
}

what is getCurrentOrientationAnchoredAdaptiveBannerAdSize suppose to be??