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From Tom Hill <solr-l...@worldware.com>
Subject Re: RE: maybe I hit a bug of Term ?
Date Fri, 10 Dec 2010 18:04:38 GMT
Hi Sariny,

What Uwe was saying is that the definition for hashCode is found in
the docs for Object, and it applies to all implementations of
hashCode.

It says:

"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."

The implementation of Maps, etc., understand this, and use it
appropriately. So, if you write your own Map implementation, you may
have to care about this, but in the general case, you can just use any
Collection and it will work.

Tom



2010/12/10 Sariny <sariny@gmail.com>:
> Object.hashCode() is "implemented by converting the internal address of the object into
an integer",
>
> Term.hashCode() has override the default implemention,so,this question has nothing todo
with Object.hashCode().
>
> I think I should try another way to cache filter results...
>
>
>
>>Hashcodes are not guaranteed to be different. See Object#hashCode()
>>javadocs.
>>
>>-----
>>Uwe Schindler
>>H.-H.-Meier-Allee 63, D-28213 Bremen
>>http://www.thetaphi.de
>>eMail: uwe@thetaphi.de
>>
>>> -----Original Message-----
>>> From: Sariny [mailto:sariny@gmail.com]
>>> Sent: Friday, December 10, 2010 3:34 PM
>>> To: java-user
>>> Subject: maybe I hit a bug of Term ?
>>>
>>>
>>>              Hi, two different Term get the same hashCode,  lucene
>>> version 3.0.2
>>>
>>>              System.out.println(new
>>> Term("manu_id",NumericUtils.intToPrefixCoded(111)).hashCode());
>>>         System.out.println(new
>>> Term("manu_id",NumericUtils.intToPrefixCoded(402)).hashCode());
>>>
>>>         a bug?
>>>
>>>
>>> ---------------------------------------------------------------------
>>> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
>>> For additional commands, e-mail: java-user-help@lucene.apache.org
>>
>>
>>
>>---------------------------------------------------------------------
>>To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
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>>
>
> = = = = = = = = = = = = = = = = = = = =
>
>
> Hashcodes are not guaranteed to be different. See Object#hashCode()
> javadocs.
>
> -----
> Uwe Schindler
> H.-H.-Meier-Allee 63, D-28213 Bremen
> http://www.thetaphi.de
> eMail: uwe@thetaphi.de
>
>> -----Original Message-----
>> From: Sariny [mailto:sariny@gmail.com]
>> Sent: Friday, December 10, 2010 3:34 PM
>> To: java-user
>> Subject: maybe I hit a bug of Term ?
>>
>>
>>               Hi, two different Term get the same hashCode,  lucene
>> version 3.0.2
>>
>>               System.out.println(new
>> Term("manu_id",NumericUtils.intToPrefixCoded(111)).hashCode());
>>         System.out.println(new
>> Term("manu_id",NumericUtils.intToPrefixCoded(402)).hashCode());
>>
>>         a bug?
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
>> For additional commands, e-mail: java-user-help@lucene.apache.org
>
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> For additional commands, e-mail: java-user-help@lucene.apache.org
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org
> For additional commands, e-mail: java-user-help@lucene.apache.org
>
>

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