What is the memory consumption of an object in Java?

Question

Is the memory space consumed by one object with 100 attributes the same as that of 100 objects, with one attribute each?

How much memory is allocated for an object?<

Answer 1

The question will be a very broad one.

It depends on the class variable or you may call as states memory usage in java.

It also has some additional memory requirement for headers and referencing.

The heap memory used by a Java object includes

• memory for primitive fields, according to their size (see below for Sizes of primitive types);

• memory for reference fields (4 bytes each);

• an object header, consisting of a few bytes of "housekeeping" information;

Objects in java also requires some "housekeeping" information, such as recording an object's class, ID and status flags such as whether the object is currently reachable, currently synchronization-locked etc.

Java object header size varies on 32 and 64 bit jvm.

Although these are the main memory consumers jvm also requires additional fields sometimes like for alignment of the code e.t.c.

Sizes of primitive types

boolean & byte -- 1

char & short -- 2

int & float -- 4

long & double -- 8