How can I use two versions of the same library in the same project in Java? [duplicate]

Question

Let's say I'm using xmlsec-1.5.8.jar for one part of my application (it has always used this).

Then let's say I'm adding a new feature to my application and the new feature requires the use of xmlsec-2.0.5.jar.

I don't want to replace xmlsec's usage for all the old code because I don't want to re-test all the code that has already been working (much of the code of which I don't know how it works because it was created before I arrived at this company).

Is there a way in Java to use xmlsec-1.5.8.jar classes in one part of my project and then to use xmlsec-2.0.5.jar in another part?

Answer 1

You need to look into class loaders.

It's pretty tricky, but here's a good explanation for you.

Java, Classpath, Classloading => Multiple Versions of the same jar/project

You'll probably have to unload the old jar, load the new jar, run whatever the new function are, then unload that newer jar and reload the older jar.