In Java world, the solution to this issue is pretty simple. A typical Java application consists of a number of .jar files (think libraries or swc) and there is a concept of a class path. If a program needs to use a class MyGreatCreation, the Java class loader tries to find it based on the classes or jars listed in the classpath. If there is more than one version of this class in the path, the class loader will grab the first one. This greatly simplifies deploying any patches in Java production applications. Just make changes to your class and place it in the jar that is listed first in the classpath. Then deploy just this jar in production, and the loader will be happy to pick up the brand new version of MyGreatCreation.