Re: hashCode
On 8/27/2012 9:19 PM, markspace wrote:
On 8/27/2012 6:58 PM, Patricia Shanahan wrote:
On 8/27/2012 5:03 PM, markspace wrote:
...
For example, in C, one can always hash based on memory address. In Java
we don't have that option, so hashcode() takes the place of the
intrinsic property of an address.
...
In Java we have System.identityHashCode() which provides an address-like
hash code for any object.
I think System.identityHashCode() is the (same as the) default
implementation for Object::hashCode(), yes?
Yes, but it could have been written, with a slightly different
explanation, without putting hashCode() in Object.
So there's a small bit of evidence in support of the idea that
Object::hashCode() is meant to mimic the idea of just hashing on address.
I don't think you need such indirect evidence:
"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.) "
[From the Object API documentation.]
Patricia
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