Yes, in 64-bit HotSpot every object has a 16-byte header, and it applies to arrays if by that you mean that each object in an array still has a header. There's

Yes, in 64-bit HotSpot every object has a 16-byte header, and it applies to arrays if by that you mean that each object in an array still has a header. There's a good overview of what that space is used for here: https://wiki.openjdk.java.net/display/lilliput/Main https://wiki.openjdk.java.net/display/lilliput/Main