Detecting java , ant script needed

Hi Friends,
I have a ant based installer. Now,I want to write an ant script that should detect if java is already installed on the system or not.If not, it should try to install java that is there with the installer package.
So,any help as to how to accomplish this??
Thanks

Since Ant needs Java to run, it would be quite a miracle to get it to install Java if it isn't installed already

Thanks for your reply.I can try some other way to detect java for eg, I could run a batch script to start with,that should check to see if java is there or not.

If yes,launches the ant installer otherwise starts java installation.

Is that feasible?Any help on that??

Unix/Linux:

java -version >/dev/null || install-java.sh

Of course, if Java isn't installed, you probably didn't have an install-java sehll script either.