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	<201012110131124712723@gmail.com>
Date: Fri, 10 Dec 2010 10:04:38 -0800
Message-ID: <AANLkTi=qW9B1cpCQ2qYcx+GWwk5R42vH-9fQmYPkN86f@mail.gmail.com>
Subject: Re: RE: maybe I hit a bug of Term ?
From: Tom Hill <solr-list@worldware.com>
To: java-user@lucene.apache.org
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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 t=
he object into an integer",
>
> Term.hashCode() has override the default implemention,so,this question ha=
s 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 ?
>>>
>>>
>>> =A0 =A0 =A0 =A0 =A0 =A0 =A0Hi, two different Term get the same hashCode=
, =A0lucene
>>> version 3.0.2
>>>
>>> =A0 =A0 =A0 =A0 =A0 =A0 =A0System.out.println(new
>>> Term("manu_id",NumericUtils.intToPrefixCoded(111)).hashCode());
>>> =A0 =A0 =A0 =A0 System.out.println(new
>>> Term("manu_id",NumericUtils.intToPrefixCoded(402)).hashCode());
>>>
>>> =A0 =A0 =A0 =A0 a bug?
>>>
>>>
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>>
>>
>>
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>
> =3D =3D =3D =3D =3D =3D =3D =3D =3D =3D =3D =3D =3D =3D =3D =3D =3D =3D =
=3D =3D
>
>
> 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 ?
>>
>>
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 Hi, two different Term get the same hashCode=
, =A0lucene
>> version 3.0.2
>>
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 System.out.println(new
>> Term("manu_id",NumericUtils.intToPrefixCoded(111)).hashCode());
>> =A0 =A0 =A0 =A0 System.out.println(new
>> Term("manu_id",NumericUtils.intToPrefixCoded(402)).hashCode());
>>
>> =A0 =A0 =A0 =A0 a bug?
>>
>>
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>> 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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