code: private int getIndex(PdfName key) {
  		for (int i = 0; i < VIEWER_PREFERENCES.length; i++) {
  			if (VIEWER_PREFERENCES[i].equals(key))
  				return i;
  		}
  		return -1;
  	}
docs: Given a key for a viewer preference (a PdfName object),
  this method returns the index in the VIEWER_PREFERENCES array.
  @param key	a PdfName referring to a viewer preference
  @return	an index in the VIEWER_PREFERENCES array