Objects IDs

Question

HI, I have a problem in hashcode(). About the hash code i think that for every object which is created from same class have unique hash code. But By using java debug interface when i get some class creation events from two different objects (of same class) i get same hash code.
I want to get the "called method's" original "calling object" and not the "calling object's class". when i have same hashcode for all objects then i cannot distinguish that which object have called the method. and all method events have same hashcode also.
What I want is.........
Why this things happens and if i want to get a unique ID for every individual object (even if they are of same type) and then try to distinguish that which objeddct have clled method then what can be possible solution.
This is from the Object API;
public int hashCode()
Returns a hash code value for the object. This method is supported for the benefit of hashtables such as those provided by java.util.Hashtable.
The general contract of hashCode is:
Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
It is not required that if two objects are unequal according to the equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results.
However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hashtables.
As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)

Answer 1

System.identityHashcode(Object o); is not required to return -unique- values for each object, at least according to the documentation and I quote...
"As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)"
If this is true then you cannot rely on System.identityHashcode to provide unique hashcodes.
If you really want to uniquely identify Objects then you need to look at GUID's (Globally Unique IDentifiers).
Here is a link that can help you with that.
http://www.webdav.org/specs/draft-leach-uuids-guids-01.txt