code: @Override
      public void close()
      {
          if(workbook != null)
              workbook.close();
  
          try
          {
              if(writableWorkbook != null)
                  writableWorkbook.close();
          }
          catch(IOException e)
          {
          }
          catch(WriteException e)
          {
          }
      }
docs: Close the workbook.