text: public HSSFCell getCell(int cellnum, MissingCellPolicy policy) {HSSFCell cell = retrieveCell(cellnum);switch (policy) {case RETURN_NULL_AND_BLANK:return cell;case RETURN_BLANK_AS_NULL:boolean isBlank = (cell != null && cell.getCellType() == CellType.BLANK);return (isBlank) ? null : cell;case CREATE_NULL_AS_BLANK:return (cell == null) ? createCell(cellnum, CellType.BLANK) : cell;default:throw new IllegalArgumentException("Illegal policy " + policy);}}