Compare two ZonedDateTime with ignoring the Zone

Med Elgarnaoui 0
Viewed 37

Compare two ZonedDateTime with ignoring the Zone:

Example:

2022-08-17 03:30:00+02 compare 2022-08-17 03:30:00+01 must give true

I Have a stream that must compare each object with others using this Date:

Set<Tele> jPointsSet = jPoints.stream()
                .collect(Collectors.toCollection(() -> 
                                new TreeSet<>(Comparator.comparing(Tele::getDateM))));

the getDateM is ZonedDateTime so I would like when use Comparator.comparing(Tele::getDateM)) ignore the Zone

zoneddatetime java-stream java
1 Answers

As @OH GOD SPIDERS said in the comments, you can extract LocalDateTime from a ZonedDateTime.

Comparator.comparing(tele -> tele.getDateM().toLocalDateTime())

But be aware that if two LocalDateTime instances are equal, it doesn't necessarily mean that they're describing the same point in time. In order to establish comparison based on a specific point in the global timeline, you need to use Instant.

Comparator.comparing(tele -> tele.getDateM().toInstant())

Sidenote: while dealing with a TreeSet, it's more handy to use NavigableSet interface as an abstract type. It gives you access to methods like pollFirst(), pollLast(), lower(), higher(), etc. which are not declared in the Set interface.

Alexander Ivanchenko0
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