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https://issues.apache.org/jira/browse/LUCENENET-437?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13067370#comment-13067370
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Troy Howard commented on LUCENENET-437:
---------------------------------------
>From the docs for List.hashCode():
"Returns the hash code value for this list. The hash code of a list is defined
to be the result of the following calculation:
hashCode = 1;
Iterator i = list.iterator();
while (i.hasNext()) {
Object obj = i.next();
hashCode = 31*hashCode + (obj==null ? 0 : obj.hashCode());
}
This ensures that list1.equals(list2) implies that
list1.hashCode()==list2.hashCode() for any two lists, list1 and list2, as
required by the general contract of Object.hashCode."
The contract intended for Object.hashCode() specifically includes that
object1.equals(object2) == object1.hashCode().equals(object2.hashCode()).
This is stated here:
http://download.oracle.com/javase/1.4.2/docs/api/java/lang/Object.html#hashCode()
Quoted:
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.)"
Again, this is Java's code contract, which was in some cases, improperly
implemented in the .NET CLR.
> Port Contrib.Shingle from Java
> ------------------------------
>
> Key: LUCENENET-437
> URL: https://issues.apache.org/jira/browse/LUCENENET-437
> Project: Lucene.Net
> Issue Type: Task
> Components: Lucene.Net Contrib, Lucene.Net Test
> Affects Versions: Lucene.Net 2.9.4, Lucene.Net 2.9.4g
> Reporter: Troy Howard
> Assignee: Troy Howard
> Priority: Minor
> Fix For: Lucene.Net 2.9.4, Lucene.Net 2.9.4g
>
>
> Port Contrib.Shingle from Java
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