Java 8: Convert file time (milliseconds from 1970) to RFC 1123 format

Question

This seems like it should be simple, but so far nothing I try is working. Basically I want to convert a file time in milliseconds from 1970 (the usual) to a TemporalAccessor

Answer 1

Milliseconds since 1970 is known as "epoch time", and Instant has the static method Instant.ofEpochMilli(long) to support creation from a long number of milliseconds. Conceptually Instant represents a single moment (long seconds + int nanoseconds) in "the standard Java epoch", so representing file time as an Instant is the correct JSR-310 way to do it.

FileTime also has a fromMillis(long) static method for the same purpose.

In this case, the conversion wasn't the problem—it was the lack of timezone as Sleafar identified first, as reflected in your edited question.