for example if i create an extension like *.kylix  and i would like it to asociate with my java program, So after user clicking  file like
document.kylix  my java program will recive through main(String...) file parameter etc. I know that Azeraus is using it for *.torrent files and i was wondering if it can be done in pure java code, of course i am not talking about manualy asociating by user (in windows it can be done in explorer folder menu) but as i said i would like it to make in pure java, probably it is not possible without native libs, but i would like to ask anyway.

theoreticaly i could make seperate *.jar files with simple class inside that could launch my program, it could be done everywhere where double clicking jar is working (becouse some older versions of winrar progs were asociating *.jar files to themselve not to java jre, but now they are not doing it). It is good solution but maybe it can be done in another way...

>AFAIK this is OS dependant.

Yes.

>I know of no way to set file associations from Java.

You can do that with webstart (1.5+)

http://java.sun.com/j2se/1.5.0/docs/guide/javaws/developersguide/syntax.html#information
>I suspect Azureus sets it in their installer.

Yes.

thanx you all it was is very helpfull