@InterfaceAudience.Private
public interface HeapSize

Implementations can be asked for an estimate of their size in bytes.

Useful for sizing caches. Its a given that implementation approximations do not account for 32 vs 64 bit nor for different VM implementations.

An Object's size is determined by the non-static data members in it, as well as the fixed Object overhead.

For example:

 public class SampleObject implements HeapSize {

   int [] numbers;
   int x;
 }