Did you see that Sweet Home 3D is also available as a Java Web Start application at http://sweethome3d.sourceforge.net/download.html ?

I could build a Jar file without a bundled JRE, but felt that Java Web Start solution was enough and better at this time (a Jar file may be run with a double click, but you don't get file extension associations and program icon).
Why would you need such a Jar file ?