Date and Calendat.getTime() not the same exact freaking thing?

[lbrtchx]

Hi,
~
I am parsing some data from archived files out of Unix file system
listings
~
The thing is that I decided to store the date as a long since the
Epoch, so that people from any locales can see it accordingly by a
simple reformatting on the fly
~
But, when I parse the date data, such as "Nov 10 2003" and build a
Calendar Object:
~
System.out.println("// __ aYr: |" + aYr + "|");
System.out.println("// __ aMonth: |" + aMonth + "|");
System.out.println("// __ aDayOfMonth: |" + aDayOfMonth + "|");
// __
try{
int iYr = Integer.parseInt(aYr);
int iMnth = HMKMIx.get(aMonth.toUpperCase());
int iDay = Integer.parseInt(aDayOfMonth);
System.out.println("// __ |" + iYr + "|" + iMnth + "|" + iDay + "|");
// __
Calendar Kal = Calendar.getInstance();
Kal.set(Calendar.YEAR, iYr);
Kal.set(Calendar.MONTH, iMnth);
Kal.set(Calendar.DAY_OF_MONTH, iDay);
// __ http://java.sun.com/javase/6/docs/api/java/util/Calendar.html#time
Date Dt = Kal.getTime();
System.out.println("// __ Dt: |" + Dt + "|");
lTm = Dt.getTime();
System.out.println("// __ lTm: |" + lTm + "|");
// __
}catch(NumberFormatException NFX){
~
using:
~
HMKMIx = new HashMap<String, Integer>();
HMKMIx.put("JAN", Calendar.JANUARY);
HMKMIx.put("FEB", Calendar.FEBRUARY);
HMKMIx.put("MAR", Calendar.MARCH);
HMKMIx.put("APR", Calendar.APRIL);
HMKMIx.put("MAY", Calendar.MAY);
HMKMIx.put("JUN", Calendar.JUNE);
HMKMIx.put("JUL", Calendar.JULY);
HMKMIx.put("AUG", Calendar.AUGUST);
HMKMIx.put("SEP", Calendar.SEPTEMBER);
HMKMIx.put("OCT", Calendar.OCTOBER);
HMKMIx.put("NOV", Calendar.NOVEMBER);
HMKMIx.put("DEC", Calendar.DECEMBER);
~
I am getting inconsistent results
~
// __ |-rw-rw-r-- 1 gbnewby pg 113214 Nov 10 2003 10002.zip|
1/0/0/0/10002|
// __ aYr: |2003|
// __ aMonth: |Nov|
// __ aDayOfMonth: |10|
// __ |2003|10|10|
// __ Dt: |Mon Nov 10 04:46:19 EST 2003|
// __ lTm: |1068457579812|
// __ |10002.zip|1/0/0/0/10002|113214|gbnewby|pg|-rw-rw-r--|
1068457579812|
~
// __ |-rw-rw-r-- 1 gbnewby pg 145317 Nov 10 2003 10003.zip|
1/0/0/0/10003|
// __ aYr: |2003|
// __ aMonth: |Nov|
// __ aDayOfMonth: |10|
// __ |2003|10|10|
// __ Dt: |Mon Nov 10 04:46:19 EST 2003|
// __ lTm: |1068457579814|
// __ |10003.zip|1/0/0/0/10003|145317|gbnewby|pg|-rw-rw-r--|
1068457579814|
~
// __ |-rw-rw-r-- 1 gbnewby pg 120858 Nov 10 2003 10004.zip|
1/0/0/0/10004|
// __ aYr: |2003|
// __ aMonth: |Nov|
// __ aDayOfMonth: |10|
// __ |2003|10|10|
// __ Dt: |Mon Nov 10 04:46:19 EST 2003|
// __ lTm: |1068457579818|
// __ |10004.zip|1/0/0/0/10004|120858|gbnewby|pg|-rw-rw-r--|
1068457579818|
~
I am using a Date object in order to get the time in millis because
the calendar class doesn't give ti to you directly
~
Why on earth is that happening? Even if they are just a few
milliseconds apart it should not be happening?
~
Is it possibly, obviously a bug or another homely and unspecified
semantics from java's date/calendar/time handling?
~
Thanks
lbrtchx

 

[Bobby Quinne]

Have a look at java.text.SimpleDateFomat. You should be able to get
the Date into the desired output format

 

[GArlington]

Hi,
~
I am parsing some data from archived files out of Unix file system
listings
~
The thing is that I decided to store the date as a long since the
Epoch, so that people from any locales can see it accordingly by a
simple reformatting on the fly
~
But, when I parse the date data, such as "Nov 10 2003" and build a
Calendar Object:
~
System.out.println("// __ aYr: |" + aYr + "|");
System.out.println("// __ aMonth: |" + aMonth + "|");
System.out.println("// __ aDayOfMonth: |" + aDayOfMonth + "|");
// __
try{
int iYr = Integer.parseInt(aYr);
int iMnth = HMKMIx.get(aMonth.toUpperCase());
int iDay = Integer.parseInt(aDayOfMonth);
System.out.println("// __ |" + iYr + "|" + iMnth + "|" + iDay + "|");
// __
Calendar Kal = Calendar.getInstance();
Kal.set(Calendar.YEAR, iYr);
Kal.set(Calendar.MONTH, iMnth);
Kal.set(Calendar.DAY_OF_MONTH, iDay);
// __http://java.sun.com/javase/6/docs/api/java/util/Calendar.html#time
Date Dt = Kal.getTime();
System.out.println("// __ Dt: |" + Dt + "|");
lTm = Dt.getTime();
System.out.println("// __ lTm: |" + lTm + "|");
// __
}catch(NumberFormatException NFX){
~
using:
~
HMKMIx = new HashMap<String, Integer>();
HMKMIx.put("JAN", Calendar.JANUARY);
HMKMIx.put("FEB", Calendar.FEBRUARY);
HMKMIx.put("MAR", Calendar.MARCH);
HMKMIx.put("APR", Calendar.APRIL);
HMKMIx.put("MAY", Calendar.MAY);
HMKMIx.put("JUN", Calendar.JUNE);
HMKMIx.put("JUL", Calendar.JULY);
HMKMIx.put("AUG", Calendar.AUGUST);
HMKMIx.put("SEP", Calendar.SEPTEMBER);
HMKMIx.put("OCT", Calendar.OCTOBER);
HMKMIx.put("NOV", Calendar.NOVEMBER);
HMKMIx.put("DEC", Calendar.DECEMBER);
~
I am getting inconsistent results
~
// __ |-rw-rw-r-- 1 gbnewby pg 113214 Nov 10 2003 10002.zip|
1/0/0/0/10002|
// __ aYr: |2003|
// __ aMonth: |Nov|
// __ aDayOfMonth: |10|
// __ |2003|10|10|
// __ Dt: |Mon Nov 10 04:46:19 EST 2003|
// __ lTm: |1068457579812|
// __ |10002.zip|1/0/0/0/10002|113214|gbnewby|pg|-rw-rw-r--|
1068457579812|
~
// __ |-rw-rw-r-- 1 gbnewby pg 145317 Nov 10 2003 10003.zip|
1/0/0/0/10003|
// __ aYr: |2003|
// __ aMonth: |Nov|
// __ aDayOfMonth: |10|
// __ |2003|10|10|
// __ Dt: |Mon Nov 10 04:46:19 EST 2003|
// __ lTm: |1068457579814|
// __ |10003.zip|1/0/0/0/10003|145317|gbnewby|pg|-rw-rw-r--|
1068457579814|
~
// __ |-rw-rw-r-- 1 gbnewby pg 120858 Nov 10 2003 10004.zip|
1/0/0/0/10004|
// __ aYr: |2003|
// __ aMonth: |Nov|
// __ aDayOfMonth: |10|
// __ |2003|10|10|
// __ Dt: |Mon Nov 10 04:46:19 EST 2003|
// __ lTm: |1068457579818|
// __ |10004.zip|1/0/0/0/10004|120858|gbnewby|pg|-rw-rw-r--|
1068457579818|
~
I am using a Date object in order to get the time in millis because
the calendar class doesn't give ti to you directly
~
Why on earth is that happening? Even if they are just a few
milliseconds apart it should not be happening?
~
Is it possibly, obviously a bug or another homely and unspecified
semantics from java's date/calendar/time handling?
~
Thanks
lbrtchx

I am not sure what is your complaint about?
You create new instance of Calendar object (it is inited by default
with CURRENT date/time [incl ms]), then you set a DATE, BUT do not
change the time, and then you complain that three separate objects are
different???
They were NOT created at the same moment of time -> so they are bound
to be different...

 

[Alan Krueger]

I am using a Date object in order to get the time in millis because
the calendar class doesn't give ti to you directly
~
Why on earth is that happening? Even if they are just a few
milliseconds apart it should not be happening?

Did you read the Javadoc on Calendar.getInstance()?

"Gets a calendar using the default time zone and locale. The Calendar
returned is based on the current time in the default time zone with
the default locale."

The sample code you included only sets YEAR, MONTH, and DAY_OF_MONTH.
You're not setting the time at all, including the milliseconds, you're
seeing a Date object for the specified date but the *time when you
created it*. Of course this will change for each instance.

I'd also recommend omitting the excess tildes in your post and
unnecessary slashes in your code, it's superfluous visual noise.

 

[Stefan Ram]

"Gets a calendar using the default time zone and locale. The Calendar
returned is based on the current time in the default time zone with
the default locale."

Actually, »current time« might be somewhat ambigous,
as there are several times, that might be deemed »current«:

- The time of the writing of the documentation
- The time of the reading of the documentation
- The time of the compilation of the call
- The time of the execution of the call
- The time of a read access to the calendar object

So the wording could be changed to »based on a time that is
not before the time of the latest sequence point before the
call of this operation and not later than the earliest
sequence point after the call of this operation«.

 

[Alan Krueger]

Actually, »current time« might be somewhat ambigous,
as there are several times, that might be deemed »current«:

- The time of the writing of the documentation
- The time of the reading of the documentation
- The time of the compilation of the call
- The time of the execution of the call
- The time of a read access to the calendar object

You must be a blast at parties.

 

[Roedy Green]

Calendar has a built-in TimeZone. Date does not.

See http://mindprod.com/jgloss/calendar.html

These are two of the most gotcha-ridden classes in all of Java.

 

[Roedy Green]

You must be a blast at parties.

It think he wrote it in German, then translated. Germans have special
genes for parsing that leave the rest of us in the dust.

 

[lbrtchx]

Did you read the Javadoc onCalendar.getInstance()?

"Gets acalendarusing the default time zone and locale. TheCalendar
returned is based on the current time in the default time zone with
the default locale."

The sample code you included only sets YEAR, MONTH, and DAY_OF_MONTH.
You're not setting the time at all, including the milliseconds, you're
seeing aDateobject for the specifieddatebut the *time when you
created it*. Of course this will change for each instance.

~
THAT DESCRIBES EXACTLY MY MISTAKEN ASSUMPTIONS. In case someone runs
into the same issues.
~
Here is it what you should do:
~
in your ctor get and Instance of a Calendar and immediately set the
Time In Millis to 0
~
Kal = Calendar.getInstance();
Kal.setTimeInMillis(0);
~
then you can use a Calendar object for parsing/verifying actual dates
and get the Epoch time, a la
~
int iYr = Integer.parseInt(aYr);
int iMnth = HMKMIx.get(aMonth.toUpperCase());
int iDay = Integer.parseInt(aDayOfMonth);
// __
Kal.set(Calendar.YEAR, iYr);
Kal.set(Calendar.MONTH, iMnth);
Kal.set(Calendar.DAY_OF_MONTH, iDay);
// __ http://java.sun.com/javase/6/docs/api/java/util/Calendar.html#time
Date Dt = Kal.getTime();
lLModTm = Dt.getTime();
~

I'd also recommend omitting the excess tildes in your post and
unnecessary slashes in your code, it's superfluous visual noise.

~
... to you. It helps me jot down my comments and track progress once
I print my relatively large code bases
~
Thanks again
lbrtchx