datetime - ISO8601 format in java given seconds

How do I get a string in Java in ISO8601 given the number of seconds
since the epoch? I'm having trouble finding it anywhere.

I want the format to look something like
this:
2000-06-31T19:22:15Z

Using just
Date d = new Date(# of milliseconds from my # of seconds) gives me a date in 1970 when I
should be getting something in 2000.

Answer

The main problem you are probably having, is
that June 2000 only had 30 days. That being said instead of using
Date, you could use a LocalDateTime
with href="https://docs.oracle.com/javase/8/docs/api/java/time/LocalDateTime.html#ofEpochSecond-long-int-java.time.ZoneOffset-"
rel="nofollow noreferrer">LocalDateTime.ofEpochSecond(long, int,
ZoneOffset)
like

long epochSecond =
            962392935L;
int nanoOfSecond = 0;
ZoneOffset offset =
            ZoneOffset.UTC;
LocalDateTime ldt = LocalDateTime.ofEpochSecond(epochSecond,
            nanoOfSecond,
            offset);
System.out.println(DateTimeFormatter.ofPattern("yyyy-MM-dd'T'HH:mm:ss'Z'").format(ldt));

Which
should be all you need to see

2000-06-30T19:22:15Z

which
is like your requested output.