i am newbie on odk. i am java developer and need to develop a simple application which take xls file as input will convert it to xml and render it like done on https://opendatakit.org/xlsform/. is there any library (jar) and sample code to accomplish it?
These are quite different beasts... First:
XML-to-XML is really the domain of XSLT; there are a number of comprehensive open source tools tailored specifically to accomplish this. Whereas...
XLSForm Online is basically a wrapper for pyxform, which is the primary tool used to convert an XLS spreadsheet representation of a form to an actual XML XForm, which can then be run on a suitable XForm client like ODK Collect (Android) or Enketo (web).
sorry for typo, i mean convertion from xls to xml. i am looking for a java library (jar) for this convertion to use in my application and also looking for rendering jar file?
FYI the reference implementation for converting XLS forms to XML XForms is pyxform; so you would probably be looking for some java wrapper around that/python...