how to close() method  on  the workbook.

As described earlier for workbook we have to import the jxl.write.WritableWorkbook class.

 For creating a workbook we have to create a workbook as,
WritableWorkbook workbook = Workbook.createWorkbook(new File);
WritableSheet sht=workbook.createSheet("mysheet", 0);

/* code for adding some data to spreadsheet */
 workbook.write();       // write all the data to workbook
workbook.close();       // close the instance of the current workbook.

The close() method closes the workbook and makes the memory that have been allocated available for the garbage collection.