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Message-ID: <3b3f27c60612041754j29946ccfp9cc69a36d6dddb53@mail.gmail.com>
Date: Mon, 4 Dec 2006 19:54:15 -0600
From: "Nathan Beyer" <nbeyer@gmail.com>
To: dev@harmony.apache.org
Subject: Re: svn commit: r480871 - in
 /harmony/enhanced/classlib/trunk/modules/luni/src:
 main/java/java/lang/ProcessBuilder.java
 main/java/org/apache/harmony/luni/platform/Environment.java
 test/java/org/apache/harmony/luni/tests/java/lang/SystemTest.java
In-Reply-To: <45742354.20203@pobox.com>
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References: <20061130081959.0B5381A9846@eris.apache.org>
	 <4570467F.5010207@pobox.com>
	 <211709bc0612032250u15c98f97k6a4f103056c9476@mail.gmail.com>
	 <f944d83d0612040001j5dd61438y7e3436ccf5bf4d94@mail.gmail.com>
	 <45742354.20203@pobox.com>

That's not a magic value. A serial version UID of 1 is considered, by
some, a default value. I know that within a Eclipse, you can either
generate a value (ala serialver tool) or insert the default value
(1L).

The serial version UID is an arbitrary value that's meant to be a
marker for a given class if two serialized objects are compatible.
Using small iterative values (1, 2, etc) is really no different than
using a complex weighted calculation that changes when the class
changes. As long as the number changes or doesn't change for a given
class, then the compatability or incompatibility, respectively, is
deterministic.

-Nathan

On 12/4/06, Geir Magnusson Jr. <geir@pobox.com> wrote:
>
>
> Alexey Varlamov wrote:
> > 2006/12/4, Tony Wu <wuyuehao@gmail.com>:
> >> This class will never be serialized. I think the meanless variable
> >> here is created to avoid compiler warining.
> >
> > How about using @SupressWarnings("serial")? It is more readable IMO.
>
> Thank you.  I didn't know what to suggest, but a magic value was
> misleading w/o a comment...
>
> geir
>
> >
> >>
> >> On 12/1/06, Geir Magnusson Jr. <geir@pobox.com> wrote:
> >> >
> >> >
> >> > liangyx@apache.org wrote:
> >> > > Author: liangyx
> >> > > Date: Thu Nov 30 00:19:55 2006
> >> > > New Revision: 480871
> >> > >
> >> > > URL: http://svn.apache.org/viewvc?view=rev&rev=480871
> >> > > Log:
> >> > > Apply patch for HARMONY-2356 ([classlib][luni]The Map from
> >> System.getEnv should throw NullPointerException while get(null) and is
> >> not modifiable.)
> >> > >
> >> > > Modified:
> >> > >
> >> harmony/enhanced/classlib/trunk/modules/luni/src/main/java/java/lang/ProcessBuilder.java
> >>
> >> > >
> >> harmony/enhanced/classlib/trunk/modules/luni/src/main/java/org/apache/harmony/luni/platform/Environment.java
> >>
> >> > >
> >> harmony/enhanced/classlib/trunk/modules/luni/src/test/java/org/apache/harmony/luni/tests/java/lang/SystemTest.java
> >>
> >> > >
> >> >
> >> > > +
> >> > > +    public static class EnvironmentMap extends HashMap<String,
> >> String> {
> >> > > +
> >> > > +        private static final long serialVersionUID = 1L;
> >> > > +
> >> > > +        public EnvironmentMap() {
> >> > > +            super();
> >> > > +        }
> >> > > +
> >> > > +        public EnvironmentMap(Map<String, String> map) {
> >> > > +            super(map);
> >> > > +        }
> >> > > +
> >> > > +        public boolean containsKey(Object key) {
> >> > > +            checkParam(key);
> >> > > +            return super.containsKey(key);
> >> > > +        }
> >> >
> >> >
> >> >
> >> > I'm curious - why set the ServialVersionUID to 1?
> >> >
> >> > geir
> >> >
> >>
> >>
> >> --
> >> Tony Wu
> >> China Software Development Lab, IBM
> >>
>