I'd like to know how one might get the Jackson JSON library to deserialize JSON into an existing object? I've tried to find how to to this; but it seems to only be able to take a Class and instantiate it itself.
Or if not possible, I'd like to know if any Java JSON deserialization libraries can do it.
This seems to be a corresponding question for C#: Overlay data from JSON string to existing object instance. It seems JSON.NET has a PopulateObject(string,object).
You can do this using Jackson:
mapper.readerForUpdating(object).readValue(json);