CODEWITHSUNDEEP
javajulian-date
nzsquall
nzsquall

Reputation: 405

Convert 18 decimal Julian Timestamp with Java

I need to convert what I think is a Julian timestamp to a regular time stamp with Java.

The application that generates this timestamp is a proprietary payment system (Base24-EPS from ACI). I need to be able to pull and parse the value from the database with a Java application.

A sample timestamp value in decimal is 18 digits:

137955731472778910

With DALCI (internal tool provided by Base24-EPS), I can see this is equivalent of:

3: convert 137955731472778910 to datetime(yyyy/mm/dd hh:mm:ss);
2019/12/14 12:39:07

I found an answer here which seems to be related. But 137955731472778910 is smaller than 210866803200000000, which is the Julian timestamp for 01-JAN-1970 (epoch for unix time).

All the other Julian timestamp online converter I see, for example http://www.onlineconversion.com/julian_date.htm, have Julian date format as double 2458806.52903.

18 digits seem too long.

Do you know how can I parse this timestamp format with Java?

Many thanks.

Upvotes: 1

Views: 911

Answers (1)

Erwin Bolwidt
Erwin Bolwidt

Reputation: 31269

Assuming you are in the UTC timezone (you probably aren't, but you haven't told me what timezone you are in), I have a formula:

long timestampFromAci = ...;
long timestampJava = (timestamp - 122192460002790000L) / 10000;

Instant.ofEpochMilli(timestampJava);
new Date(timestampJava); // Old, deprecated - use java.time classes

This assumes that the conversion is linear.

Your product timestamp has 10000 units per millisecond, since there are 2145052000 milliseconds between 2019/11/19 16:48:15 and 2019/12/14 12:39:07, and the difference in your product's timestamp is 21450514084700.

If you divide these two, that's almost exactly 10000 - the difference is because your tool doesn't display fractional seconds.

Extrapolating from that, I can derive that value that your product timestamp would have for the Unix epoch op 1/1/1970 - 122192460002790000.

However, as I said, I made the assumption that you are in the UTC timezone. For every hour that your timezone is off from UTC, you need to adjust that number by 3600 seconds times 10,000,000 units product timestamp units per second.

Upvotes: 3

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