File last modified date wrong

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Marc Mendez - 21 Aug 2007 09:20 GMT

Hi,

Under W2003 (and once under XP Pro), I can't get the right last modified
date of a file.

I use :
long lastmodified = file.lastModified();
long currentTime = new GregorianCalendar().getTimeInMillis();

to know how long a file was changed.

To trace the routine, I do :

log.println("Last modified date : " + lastmodified);
GregorianCalendar t = new GregorianCalendar();
t.setTimeInMillis(lastmodified);
log.println("Last modified date (readable) :
"+t.get(Calendar.DAY_OF_MONTH)+"/"+t.get(Calendar.MONTH)+"/"+t.get(Calendar.YEAR));
log.println("Current date : " + currentTime);

A file modified on 16/07/2007 looks modified on le
16/06/2007 ! I use JRE 1.4.2. On my home computer (XP Pro), no problem.

Any idea ?

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Gordon Beaton - 21 Aug 2007 09:34 GMT

> A file modified on 16/07/2007 looks modified on le 16/06/2007 ! I
> use JRE 1.4.2.

The months are numbered starting from 0, so 6 is July, not June.

> On my home computer (XP Pro), no problem.

Can't explain that.

/gordon

--

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Marc Mendez - 21 Aug 2007 10:04 GMT

Yes you're right. But if so, it should occur on any system. Some systems
give me the right month, the other the wrong one...

>> A file modified on 16/07/2007 looks modified on le 16/06/2007 ! I
>> use JRE 1.4.2.
[quoted text clipped - 6 lines]
>
> /gordon

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Roedy Green - 21 Aug 2007 11:34 GMT

On Tue, 21 Aug 2007 10:20:42 +0200, "Marc Mendez"
<marc.mendez_SPAM_NO@bigfoot.com> wrote, quoted or indirectly quoted
someone who said :

>long lastmodified = file.lastModified();
>long currentTime = new GregorianCalendar().getTimeInMillis();

I would do it like this:

long currentTime = System..currentTimeMillis();

long filetime = file.lastModified();

static final SimpleDateFormat sdf =
new SimpleDateFormat( "EEEE yyyy/MM/dd hh:mm:ss aa zz :
zzzzzz" );

String dateString = sdf.format( new Date( filetime ) );

This way you see the time zone being used. Most often problems with
date/time are displaying in a different time zone, DST than you
thought you were.

Also check how both machines are configured in the OS.
See http://mindprod.com/applet/tz.html

see http://mindprod.com/jgloss/timezone.html
http://mindprod.com/jgloss/calendar.html
http://mindprod.com/jgloss/time.html
http://mindprod.com/jgloss/timestamp.html

Signature

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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Marc Mendez - 21 Aug 2007 19:23 GMT

That's a good idea, but a different TMZ can give a difference up to one day,
not a month ;)

> On Tue, 21 Aug 2007 10:20:42 +0200, "Marc Mendez"
> <marc.mendez_SPAM_NO@bigfoot.com> wrote, quoted or indirectly quoted
[quoted text clipped - 26 lines]
> http://mindprod.com/jgloss/time.html
> http://mindprod.com/jgloss/timestamp.html

Reply to this Message

Roedy Green - 22 Aug 2007 04:54 GMT

On Tue, 21 Aug 2007 20:23:40 +0200, "Marc Mendez"
<marc.mendez_SPAM_NO@bigfoot.com> wrote, quoted or indirectly quoted
someone who said :

>That's a good idea, but a different TMZ can give a difference up to one day,
>not a month ;)

That was not obvious to me . I did not know if you meant DDMMYYYYY or
MMDDYYYY.

I use ISO format YYYY-MM-DD since it is unambiguous.

Signature

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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Roedy Green - 22 Aug 2007 05:05 GMT

On Tue, 21 Aug 2007 10:20:42 +0200, "Marc Mendez"
<marc.mendez_SPAM_NO@bigfoot.com> wrote, quoted or indirectly quoted
someone who said :

>Under W2003 (and once under XP Pro), I can't get the right last modified
>date of a file.

I presume you are not showing us the exact code. Could some sort of
exception leave the lastModified set to an old value?

Signature

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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Marc Mendez - 22 Aug 2007 15:59 GMT

No, it was exactly the code. About the TMZ, it's DD/MM/YYYY.

> On Tue, 21 Aug 2007 10:20:42 +0200, "Marc Mendez"
> <marc.mendez_SPAM_NO@bigfoot.com> wrote, quoted or indirectly quoted
[quoted text clipped - 5 lines]
> I presume you are not showing us the exact code. Could some sort of
> exception leave the lastModified set to an old value?

Reply to this Message

Roedy Green - 23 Aug 2007 01:53 GMT

To get one possible source of confusion out the way, use SetClock to
set your time and let you know the timezone you have configured on the
various machines.

See http://mindprod.com/webstarts/setclock.html

Signature

Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com

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File last modified date wrong

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