File APIs for Java Developers
Manipulate DOC, XLS, PPT, PDF and many others from your application.
http://aspose.com/file-tools
The moose likes Beginning Java and the fly likes Hash Code Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login


Win a copy of Soft Skills this week in the Jobs Discussion forum!
JavaRanch » Java Forums » Java » Beginning Java
Bookmark "Hash Code" Watch "Hash Code" New topic
Author

Hash Code

Karthik Vaidiswaran
Greenhorn

Joined: Jan 11, 2005
Posts: 16
Please give me information about the way of finding the hashcode of an object. I have heard that hashcode of an object is the address of memory location of the object. How do I find the hashcode?

Thanks
Karthik.
Jeff Bosch
Ranch Hand

Joined: Jul 30, 2003
Posts: 805
Simple. Just invoke the hashCode() method, which every object inherits from Object. It returns an int.


Give a man a fish, he'll eat for one day. Teach a man to fish, he'll drink all your beer.
Cheers, Jeff (SCJP 1.4, SCJD in progress, if you can call that progress...)
Jeroen Wenting
Ranch Hand

Joined: Oct 12, 2000
Posts: 5093
the hashcode is NOT the address in memory of an object instance.
In fact, that would yield a hashcode which is by definition incorrect as it doesn't confirm to the hashcode definition which states explicitly that two identical objects MUST have the same hashcode.
As no two objects (whether identical or not) can exist in the same place in memory at the same time that's an impossibility if you take the object's memory address as the hashcode.


42
Jim Yingst
Wanderer
Sheriff

Joined: Jan 30, 2000
Posts: 18671
Well, the hashcode may be equal to (or directly derived from) the memory address, if we're talking about the implementation defined inside the Object class. But many classes override this definition of equals(), and thus they must also override hashCode() too for consistency. So in general the hashCode is probably not based on memory location, but in some cases it may be.


"I'm not back." - Bill Harding, Twister
Mike Gershman
Ranch Hand

Joined: Mar 13, 2004
Posts: 1272
the hashcode definition which states explicitly that two identical objects MUST have the same hashcode.

The rule is that two objects where equals() is true must have the same hashcode. If we use the default Object.equals() method, only the same object will have equals() true. In that case, the memory address will be the same.


Mike Gershman
SCJP 1.4, SCWCD in process
Karthik Vaidiswaran
Greenhorn

Joined: Jan 11, 2005
Posts: 16
Thanks for all the replies.It was helpful

Karthik.
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: Hash Code