Q:

Can I have applications using Java 1.4.2_12 and Java 1.5 on the same windows server

I have a couple of applications running on Java 1.4.2_12  and now need to add an new application that uses Java 1.5. Can I have both java versions on a windows server?

A:

Yes. You just need to make sure that each has the correct version of Java/the JRE on its CLASSPATH, PATH and JAVA_HOME environment variables.

A:

Yes: actually JDK or JRE can be just "copied" wherever you want, not "installed" (avoiding putting anything in c:\Windows\System32)
I would also recommend not using global environment variables.
That way, your applications depend entirely on local settings (local to the application), and not on external Java installation side-effects

