How to manage required, conflicting Java dependencies

Question

Say I need (its required) to use fizz-1.0.jar and buzz-2.3.2.jar in my Java project. Now, fizz-1.0.jar depends on foo-0.1.35.jar, and buzz-2.3.2.jar depends on foo-4.2.17.jar.

foo-0.1.35.jar contains a Widget class like so:

public class Widget {
    public int doSomething(int x) {
        return x++;
    }
}

foo-4.2.17.jar contains a heavily modifed version of Widget:

public class Widget {
    public Meh makeStuff() {
        return new Meh();
    }
}

Unfortunately, both fizz-1.0.jar and buzz-2.3.2.jar make heavy use of both versions of Widget.

I can't just blindly add both versions of foo-x.y.z.jar to the classpath, because whichever Widget gets loaded first will only work for either fizz-1.0.jar or buzz-2.3.2.jar.

What are my options here? Remember I must have both fizz-1.0.jar and buzz-2.3.2.jar, and must satisfy all of their transitive dependencies.

http://stackoverflow.com/questions/1553567/java-classloader-how-to-reference-different-versions-of-a-jar — orangegoat, May 29 '13 at 12:47

score 1 · Accepted Answer · answered May 29 '13 at 12:47

1

I would recommend that you use a framework which distinguishes class loads. E.g. OSGi framework. Then you can create 2 bundles - one with the fizz implementation and one with the buzz implementation. They both can contain their dependent libraries which do not conflict anymore because they are loaded from 2 different classs loaders.

Example osgi containers or "Eclipse Equinox" and "Apache Felix" but there are more.

Hope that helps.

answered May 29 '13 at 12:47

Michael Mangeng

138
7

if you don't want to use such a container, you can also load the classes on your own using urlclassloader. but this approach is more tricky :-) – Michael Mangeng May 29 '13 at 12:48

How to manage required, conflicting Java dependencies

1 Answers1