If you meant, event-based parser then there are a couple of projects out there that do this:
-
http://code.google.com/p/json-simple/
Stoppable SAX-like interface for streaming input of JSON text
This project has moved to https://github.com/fangyidong/json-simple
-
http://jackson.codehaus.org/Tutorial
Jackson Streaming API is similar to Stax API
This project has moved to https://github.com/FasterXML/jackson-core