How can I get the memory location of a object in java?

Question

I want to know the location that JVM allocates to objects being placed in the system memory.

Answer 1

This is something you probably don't want to do.

If you really want to do this, something like this code might help:

package test;  import java.lang.reflect.Field;  import sun.misc.Unsafe;  public class Addresser {     private static Unsafe unsafe;      static     {         try         {             Field field = Unsafe.class.getDeclaredField("theUnsafe");             field.setAccessible(true);             unsafe = (Unsafe)field.get(null);         }         catch (Exception e)         {             e.printStackTrace();         }     }      public static long addressOf(Object o)     throws Exception     {         Object[] array = new Object[] {o};          long baseOffset = unsafe.arrayBaseOffset(Object[].class);         int addressSize = unsafe.addressSize();         long objectAddress;         switch (addressSize)         {             case 4:                 objectAddress = unsafe.getInt(array, baseOffset);                 break;             case 8:                 objectAddress = unsafe.getLong(array, baseOffset);                 break;             default:                 throw new Error("unsupported address size: " + addressSize);         }                 return(objectAddress);     }       public static void main(String... args)     throws Exception     {            Object mine = "Hi there".toCharArray();         long address = addressOf(mine);         System.out.println("Addess: " + address);          //Verify address works - should see the characters in the array in the output         printBytes(address, 27);      }      public static void printBytes(long objectAddress, int num)     {         for (long i = 0; i < num; i++)         {             int cur = unsafe.getByte(objectAddress + i);             System.out.print((char)cur);         }         System.out.println();     } } 

But

• not portable across JVMs or even different versions
• objects can move because of GC at any time, and cannot synchronize across GCs so results might not make sense
• not tested across all architectures, endianess, etc. might make this not work everywhere