What is the size of the object in java

Question

As we all know that java uses the following data types

byte    Occupy 8 bits in memory
short   Occupy 16 bits in memory
int     Occupy 32 bits in memory
long         


        

Answer 1

The header of an object can take 8 bytes on a 32-bit JVM and 12 bytes on a 32-bit JVM.

Each primitive takes the number of bits (not bytes you indicate)

Object allocation is 8 byte aligned so there is up to 7 bytes of padding at the end of a object. i.e. the space actually used is rounded up to the next multiple of 8.

class Demo{ // 8 or 12 bytes
    byte b; // 1 byte
    int i;  // 4 bytes
    long l; // 8 bytes
}

Demo obj = new Demo();

So the size of the object can take 24 bytes on a 32-bit JVM and 32 bytes on a 64-bit JVM.