How to get the Desktop path in java

Seems not that easy...

But you could try to find an anwser browsing the code of some open-source projects, e.g. on Koders. I guess all the solutions boil down to checking the HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders\Desktop path in the Windows registry. And probably are Windows-specific.

If you need a more general solution I would try to find an open-source application you know is working properly on different platforms and puts some icons on the user's Desktop.