Formatting Todays Date

[Steve Dyke]

I use data from a remote iSeries server.
Some of the date fields are in this format 1240528.
This was done during the Y2K era.

I need to format the following into 1yyMMdd.

LocalDate.now(ZoneId.systemDefault());

[Ron McLeod]

Something like this should work:

DateTimeFormatter format = DateTimeFormatter.ofPattern("1uuMMdd");
LocalDate.now(ZoneId.systemDefault()).format(format);

DateTimeFormatter

[Lou Hamers]

That works for the title of the thread "today", but reading the post, looks like more work needed to convert that numeric format to something usable that Java understands.

Questions:

I'm not understanding how that numeric format is supposed to be parsed, is this more about how to convert that number to something usable? Some format specific to "iSeries"? (Which I'm not familiar with but maybe someone here is.)


These may not matter but I already typed them (lol)...

Are they supposed to be date/time or just date?

What timezone is this data stored in?

[Lou Hamers]

Follow up - is the length of that example number a realistic length?

Because if it's longer it's possible/probable that it's just a standard "Unix" time in seconds. Which would make this pretty easy. This 1240528 looks too short for that (but maybe you just random typed that for an example)...

[Ron McLeod]

Lou Hamers wrote:This 1240528 looks too short for that (but maybe you just random typed that for an example)...

It sounds like this for input into a legacy system where their fix for Y2K  was to prepend the date with a century indicator - 0=19XX, 1=20XX.

[Lou Hamers]

Yuck.. maybe though. I'm still not sure how to parse the rest of that number though if it's just month/day.

It doesn't seem long enough to include time either (assuming it's a real example and not just something randomly typed for an example).

[Mike Simmons]

1240528 is not a random example - it's today's date, 2024-05-28, formatted according to the format given in the original post, 1yyMMdd.  It contains no time info, only date.  This can be reversed to parse a given string as a LocalDate, e.g.

    DateTimeFormatter format = DateTimeFormatter.ofPattern("1yyMMdd");
    var dateStr = "1240528";
    var date = LocalDate.from(format.parse(dateStr));
    System.out.println(date);

[Steve Dyke]

Lou Hamers wrote:Yuck.. maybe though. I'm still not sure how to parse the rest of that number though if it's just month/day.

It doesn't seem long enough to include time either (assuming it's a real example and not just something randomly typed for an example).

1240528 is a real field value.

Rob M. was correct 1 = 20XX
24 = year
05 = Month
28 = Day

[Lou Hamers]

I see now, you wanted today's date in that legacy format. I should have caught onto that earlier. I'll blame it on tiredness.

[Carey Brown]

Steve Dyke wrote:1240528 is a real field value.

Rob M. was correct 1 = 20XX
24 = year
05 = Month
28 = Day

Do you ever have the case where the '1' is missing or replaced by a different digit?

[Mike Simmons]

If they ever use 0 for 1900s, or 2 for 2100s, then one approach would be to take that original format as a decimal number, and add 19000000.

So 1240528 + 19000000 = 20240528.  Convert that back to a String and parse it using yyyyMMdd.  That way you can easily handle any date from 1900 on to... whenever, really.

[Carey Brown]

Mike Simmons wrote:If they ever use 0 for 1900s, or 2 for 2100s, then one approach would be to take that original format as a decimal number, and add 19000000.

So 1240528 + 19000000 = 20240528.  Convert that back to a String and parse it using yyyyMMdd.  That way you can easily handle any date from 1900 on to... whenever, really.

Yes. I'm  asking "IF?".

[Paul Clapham]

Carey Brown wrote:Yes. I'm  asking "IF?".

So far the question is only about today's date, though.

[Rob Spoor]

Mike Simmons wrote:1240528 is not a random example - it's today's date, 2024-05-28, formatted according to the format given in the original post, 1yyMMdd.  It contains no time info, only date.  This can be reversed to parse a given string as a LocalDate, e.g.

    DateTimeFormatter format = DateTimeFormatter.ofPattern("1yyMMdd");
    var dateStr = "1240528";
    var date = LocalDate.from(format.parse(dateStr));
    System.out.println(date);

That LocalDate.from(format.parse(dateStr)) can be simplified as LocalDate.parse(dateStr, format), which is shorthand for format.parse(dateStr, LocalDate::from). All three create an intermediate object that is converted to a LocalDate, but the second form is shorter and (at least for me) easiest to read.