I came across a scenario where I had to convert excel spreadsheets both xls and xlsx formats into csv programmatically .
My search for a library to achieve this landed me here Apache POI . Apache POI is a Java API built for the purpose of handling Microsoft documents.
The site has an amazing collections of examples, with respect to each document type. For my scenario i.e handling excel sheets one can find list of examples available in the following link https://poi.apache.org/spreadsheet/examples.html .
I used the example ToCSV (http://svn.apache.org/repos/asf/poi/trunk/src/examples/src/org/apache/poi/ss/examples/ToCSV.java) and created a maven project. The project can be checked out from my git repo https://github.com/bharathdcs/exceltocsv .