Run this:

import java.awt.*;

public class TDesktop {
    public static void main(String args[]) {
       System.err.println("is Desktop supported? "+Desktop.isDesktopSupported());
    }
}

on Ubuntu i586 linux 11.10 or 12 it will report "false", be it Unity or Xfce4.
Plus, jdk8 around b41 would complain "can not load libgnome-2.so" and report false while jdk 7u6 b12 just says false, without complains.