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I'm reading a record of data from a cassandra table. Creating a Java object that I built. Setting all the values with what I get from the record of data (I'm getting these values from the record using Jackson). When I look at the json request I'm seeing a long doulbe like value. Wondering what format that is in? And then why it's negative? Here's what I got...

JsonNode ccEventNode = new ObjectMapper().readTree(row.getString(0));
ccEventNode.get("last_pyflt_dt")

This gives me a value of "1901-01-01". I then...

CCEvent ccEvent = new CCEvent;
ccEvent.getHistory().setLast_pyflt_dt(new SimpleDateFormat("yyyy-MM-dd").parse(ccEventNode.get("last_pyflt_dt").textValue()));

This gives me a value for the Date field I just set of "Tue Jan 01 00:00:00 EST 1901"

But when I read the JSON request once I'm done setting all the other values I am seeing the value as...

"lastPaymentFloatDate":-2177434800000

My first question is. What is that value? Is it number of minutes from a certain date? Why is it negative? It's causing issues when I send it to the webservice. When I have other dates that are like "2020-02-04" it doesn't cause any issues. It also shows me in the request a large number like the one above but it's not negative. A bit confused.

Brian Gurka
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  • Date can be represented on many ways. What `type` do you use to store it in `CCEevnt` class? What type is used to store it in `Cassandra` table? Take a look on that question: [Spring Boot Jackson date and timestamp Format](https://stackoverflow.com/questions/55256567/spring-boot-jackson-date-and-timestamp-format) – Michał Ziober Mar 06 '20 at 21:05

1 Answers1

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-2177434800000 is the number of milliseconds before the epoch time.
Epoch time is 1 January 1970 00:00:00 which is considered 0 milliseconds. Any time before it is negative and after it is positive. Think of epoch time as 0 in the number line.
You can read more about it here and here.

Also ,you can verify that -2177434800000 stands for 1901-01-01 on this epoch convertor website.

Neeraj
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  • Thank you!! Now how would i convert that back. it seems my webservice needs that value as epoch and then is returning it that way. But When i write back into cassandra, cassandra does NOT like that at all – Brian Gurka Mar 10 '20 at 14:11