Is your Ant task that builds the JAR including both the classes in target/classes and the resources in main/resources?
It wasn't but now it is and it's working, thanks. I think the folder organization inside the jar is a bit confusing now, it looks like this:
-com
-images
-sounds
-META-INF
The folders images and sounds were in resources, is that correct? I thought it should be like /resources/images inside the jar.
Thanks.