Using Java's javax.sound package to play audio seems to do something that prevents other applications from playing sound with ALSA at the same time. My sound card doesn't do hardware mixing, so I assume that ALSA's dmix is used by default, and Java is using a hw device directly instead of ALSA's default device.
I searched for a while, but couldn't find a solution.
Getting java sound to use OSS and running java inside aoss seems to workaround the problem.

Same problem
How exactly have you found a way to make it work? Thanks
Yes, how did you do it?
Hi!
Did you get java to use alsa's dmix instead of a hardware mixer? If you did, how did you do it? Could you tell, please?
Thanks in advance.
Hi Wes! Nice to come across
Hi Wes!
Nice to come across you! Just found this, not yet tried:
http://www.razorsedge.org/~mike/docs/asoundrc.html
Good luck