Json-lib is a java library for transforming beans, maps, collections, java arrays and XML to JSON and back again to beans and DynaBeans. It is based on the work by Douglas Crockford in http://www.json.org/java.
Everybody in the world, be WARNED! This is one of the worst libraries I've ever seen. It caused us a lot of trouble and we've wasted many MDs because of it. Pure evil. First, it has extremely poor performance. It caused huge latencies in our production. Serializing a very simple JSON of size ~ 1kB often took more than 1000ms! Resulting it frequent timeouts in our API. Second, the library has extremely bad, unintuitive design. There are 10 different methods doing exactly the same in each class. Finally, double 1410973165.467034 gets parsed as 1.41097318E9. Today, I've spent last 3 hours to completely remove it from our project, hoping I'll never see json-lib again. It scares me that it's still present at some places in our production code. I suggest using jackson.codehaus.org instead. It worked perfectly from the first time and is perfectly intuitive.
This is not supported by the programmer anymore and there are serious bugs in situations that should be default test cases. We used this for 2 years before finding these bugs out, and now it is tightly integrated into our app and will be hard to move off of, I would highly recommend not using this lew of other options that have better features and are currently supported, we moved to gson.