Appropriate magic. Jackson uses byte-code manipulation to get its work done, but you'll never see it nor have to interact with it -- all you see is a nicely an

Appropriate magic. Jackson uses byte-code manipulation to get its work done, but you'll never see it nor have to interact with it -- all you see is a nicely annotated class that automatically converts to and from JSON as it enters and leaves your code. For advanced use-cases you may have to ask for the ObjectMapper and convert strings yourself, but you'll never need to know how it's implemented. To my mind, appropriate magic is where you define your interface to have a simple-to-use but complete API, hiding the complexity of implementation. For example, Guava's CacheMap implementation has careful internal locking to present a consistent but high-performance thread-safe object, rather than requiring external locking or needing the caller to avoid certain combinations of actions, both of which I've seen when I've come across people who tried to implement their own. Or, in Jackson's case, high-performance data manipulation that could be done using reflection but isn't because that would be too slow.