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Re: Date/Calendar confusion

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Date	Fri, 7 Sep 2012 18:44:30 -0700 (PDT)
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Subject	Re: Date/Calendar confusion
From	Lew <lewbloch@gmail.com>
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Xref	csiph.com comp.lang.java.programmer:18601

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John B. Matthews wrote:
> Lew wrote:
>>  John B. Matthews wrote:
>>> Ulrich Scholz  wrote:
> 
> [Valuable clarifications elided.]
> 
>>>     calendar2.set(Calendar.YEAR, 1970);
>>>     calendar2.set(Calendar.MONTH, Calendar.JANUARY);
>>>     calendar2.set(Calendar.DAY_OF_MONTH, 1);
>>> 
>>>     calendar2.clear(Calendar.HOUR);
>> 
>> Better: 'calendar2.set(Calendar.HOUR, 0);'
> 
> Can I impose on you to amplify further? Is this related to "the 
> resolution rule for the time of day," mentioned in clear(int)?
> 
> <http://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html#time_resolution>
> <http://docs.oracle.com/javase/7/docs/api/java/util/Calendar.html#clear(int)>

I guess, but that's not my focus. My focus is on the fact that when you 'clear(int)', as opposed
to 'set(int,int)', the 'Calendar' instance does no reconciliation, nor can you rely on any specific 
field value such as '0'. 'clear()' sets fields to *undefined*, not a specific value. It makes no 
attempt to reconcile field values, e.g., to set a day to a valid value based on the month value
or vice versa.

So you have no promise as to what the values are after a 'clear()'. What comes out might well
surprise, as it did on that project some years ago where I encountered this situation.

-- 
Lew

Thread

Date/Calendar confusion Ulrich Scholz <d7@thispla.net> - 2012-09-06 01:03 -0700
  Re: Date/Calendar confusion nogales <nogales.manuel@gmail.com> - 2012-09-06 02:29 -0700
  Re: Date/Calendar confusion Lew <lewbloch@gmail.com> - 2012-09-06 10:21 -0700
  Re: Date/Calendar confusion "John B. Matthews" <nospam@nospam.invalid> - 2012-09-06 20:53 -0400
    Re: Date/Calendar confusion Lew <lewbloch@gmail.com> - 2012-09-07 11:01 -0700
      Re: Date/Calendar confusion "John B. Matthews" <nospam@nospam.invalid> - 2012-09-07 21:02 -0400
        Re: Date/Calendar confusion Lew <lewbloch@gmail.com> - 2012-09-07 18:44 -0700
          Re: Date/Calendar confusion "John B. Matthews" <nospam@nospam.invalid> - 2012-09-08 09:12 -0400
            Re: Date/Calendar confusion Lew <lewbloch@gmail.com> - 2012-09-08 16:51 -0700

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