This is not an answer for the OP, as he wanted the display dimensions in real pixels. I wanted the dimensions in "device-independent-pixels", and putting together answers from here https://stackoverflow.com/a/17880012/253938 and here https://stackoverflow.com/a/6656774/253938 I came up with this:
DisplayMetrics displayMetrics = Resources.getSystem().getDisplayMetrics();
int dpHeight = (int)(displayMetrics.heightPixels / displayMetrics.density + 0.5);
int dpWidth = (int)(displayMetrics.widthPixels / displayMetrics.density + 0.5);