Hey there, your problem has nothing to do with Java, strictly with the default installation of Ubuntu with IP v6 enabled

I know because I had the same problem, only it was some portforwarding I was setting up with an SSH session locally.

If you look at your NIC with 'ifconfig -a' you'll find you have not only a ipv4 address but an ipv6 one as well.

To fix this:
Change the line is /etc/modprobe.d/aliases from:

alias net-pf-10 ipv6

to

alias net-pf-10 off

Then, I rebooted and presto, no ipv6 enabled or configured anymore.