How does one juggle between multiple JDK's and JRE's on the same machine and same drive. I guess what I am trying to figure out is how do I get say application A to use JDK X OR JRE X and say application B to use JDK Y OR JRE Y , when both app. A and B are running at the same time OR when app. A is executed first and then app. B is to be executed. I hope it does make sense !! TIA for all the responses.