title: Edit existing excel files using jxl api / Apache POI
body: <p>I am interested and would like to learn more about java , how to write into existing excel sheets / manipulating the existing data. I was wondering if you could give me an idea on how to edit an existing excel file and save it using the jxl api / Apache POI
  or perhaps give me a sample program on how to edit some data in an existing excel file and then save it
  Thanks in advance !!</p>