Android Question Is there a worked example of building a library wrapper?

I've been through the site and I've looked at all the tutorials and I get so far and then I get lost (most specifically on building the Wrapper code itself).

Are there any worked examples of how to build a library wrapper? By this a mean step by step instructions of what goes where and how it should look.

I'm not big on Java so I'm working a bit blind here.

Any help would be gratefully received.

Cheers.