Although Java lacks a true sizeof () equivalent, the Instrumentation interface introduced with J2SE5 can be used to get an estimate of the size of a particular object via its getObjectSize (Object ...

Get tips for instantiating JavaScript's prototype-based objects two ways: via constructor functions or object initialization.

The Mongo object comes from the Java driver written by the guys over at 10gen. This example opens a connection to a local MongoDB instance and uses the mjormIsFun database.