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From "Digy (JIRA)" <>
Subject [Lucene.Net] [jira] [Commented] (LUCENENET-437) Port Contrib.Shingle from Java
Date Mon, 18 Jul 2011 22:38:57 GMT


Digy commented on LUCENENET-437:

Java Docs says:
public boolean equals(Object o)
    Compares the specified object with this list for equality. Returns true if and only if
the specified object is also a list, both lists have the same size, and *all corresponding
pairs of elements in the two lists are equal* [No reference for Hashcode - DIGY]. (Two elements
e1 and e2 are equal if (e1==null ? e2==null : e1.equals(e2)).) In other words, two lists are
defined to be equal if they contain the same elements in the same order. This definition ensures
that the equals method works properly across different implementations of the List interface.

Yes, the sample was from Eric Lippert's blog to show why GetHashCode should not be used for
comparing objects.
bq. The issue you're describing is more of a problem with the .NET implementation of GetHashcode()
rather than the correctness of using hashcode for comparison. 
No, the problem is not in the implementation of GetHashCode. In any implementation, you may
have some unexpected collisions(since it is a 4-byte number). GetHashCode isn't meant for
uniqueness or object identification. It's  meant to provide a random distribution.
Therefore the problem really lies in using it for equality comparison.


> Port Contrib.Shingle from Java
> ------------------------------
>                 Key: LUCENENET-437
>                 URL:
>             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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