Hi SK,
Please have a look at the below SAP KBA's and link, they doesn't contain exactly the code that you require but can be modified to achieve your requirement.
1778822 - How to list all the user for each group using BusinessObjects Enterprise Java SDK
1302317 - How to list out the folder objects on the enterprise system using the Java BusinessObjects Enterprise SDK
http://scn.sap.com/docs/DOC-6035
Hope this helps.
Regards
Rajarsh