Re: Memory Footprint of an Object

Codedigestion wrote:


My best idea is getting used memory before and after
construction the object.

See below for a primitive example.

Arne

package october;

public class SizeOf<T> {
     private final static int N = 1000000;
     public static long mem() {
         Runtime rt = Runtime.getRuntime();
         return rt.totalMemory() - rt.freeMemory();
     }
     public static void main(String[] args) {
         A[] arrA = new A[N];
         long m1 = mem();
         for(int i = 0; i < N; i++) {
             arrA[i] = new A();
         }
         long m2 = mem();
         System.out.println("sizeof A = " + (m2 - m1)*1.0/N);
         B[] arrB = new B[N];
         long m3 = mem();
         for(int i = 0; i < N; i++) {
             arrB[i] = new B();
         }
         long m4 = mem();
         System.out.println("sizeof B = " + (m4 - m3)*1.0/N);
     }
}

class A {
     public int a;
     public int b;
}

class B {
     public byte b1;
     public byte b2;
}