[jdom-interest] hashCode() and equals()
noamt at yahoo.com
Thu May 31 14:01:58 PDT 2001
You all have the Java api. Take a look at the javadoc for Object.hashCode().
The interesting part is this:
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
* 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.
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