[cgh]

In Java-land, OSGi was invented to solve this very problem. Every module has its own classloader so module A can load C 1.0 and module B can load C 1.1. Modules are registered and other modules can look them up in the registry and call them so A can look up and then call B without conflicts.

[ExpiredLink]

OSGi is good in theory but too much ado for most real-world projects.

[cgh]

Agreed. The Spring support helps a lot though. But there's no question that OSGi is one of the final big xml holdouts in Java-land.