How to get DayOfWeek from an Instant.now()

问题

Assuming the following code...

Instant x = Instant.now();

How do I get day of week from x?

回答1:

You have to convert it to ZonedDateTime

Instant.now().atZone(ZoneId.systemDefault()).getDayOfWeek()

回答2:

I have awarded points to techtabu, but I ended up using atOffset instead. Here is where I ended up...

int currentDayOfWeekValue = Instant.now().atOffset(ZoneOffset.UTC).getDayOfWeek().getValue();

I am amazed how difficult the Java8 datetime libraries are. There are so many variations of similar concepts...

• Instant
• LocalDate
• LocalTime
• LocalDateTime
• OffsetDateTime
• ZoneOffset
• ZonedDateTime

Rhetorical questions:

Is Zulu and UTC the same or different?

What is the timezone associated with Instant.now() - the results suggest Zulu?

Why can't I manipulate an Instant object like a LocalDateTime - methods are similar but different?

How are ZonedDateTime and OffsetDateTime different - they seem to be addressing the same concept.

回答3:

Calendar.getInstance().get(Calendar.DAY_OF_WEEK); 

will give you the same result

来源：https://stackoverflow.com/questions/56364324/how-to-get-dayofweek-from-an-instant-now