CODEWITHSUNDEEP
javajava-8java-time
Tiny
Tiny

Reputation: 27909

Comparing instances of java.time.ZonedDateTime ignoring seconds and milliseconds instants from comparisons in Java 8

I am looking for an equivalent way of Joda Time in Java 8 comparing instances of org.joda.time.DateTime (with a time zone specified) ignoring seconds and milliseconds from comparisons as follows.

DateTimeFormatter formatter = DateTimeFormat.forPattern("dd-MMM-yyyy hh:mm:ss:SSS a Z").withZone(DateTimeZone.forID("Asia/Kolkata"));
DateTime first = formatter.parseDateTime("16-Feb-2012 12:03:45:999 AM +05:30");
DateTime second = formatter.parseDateTime("16-Feb-2012 12:03:55:999 AM +05:30");

DateTimeComparator comparator = DateTimeComparator.getInstance(DateTimeFieldType.minuteOfHour());
int compare = comparator.compare(first, second);
System.out.println("compare : " + compare);

The comparison returns 0 meaning that both the objects have been considered equal after ignoring seconds and milliseconds instants from the comparison.

Fields of a magnitude less than the lower limit specified with DateTimeFieldType are ignored here.

What is the equivalent way of doing the same thing using the Java Time API in Java 8?

To be honest, I did not succeed to achieve the same in Java 8 with my attempts.

Upvotes: 11

Views: 13485

Answers (2)

Viet
Viet

Reputation: 3409

Try ChronoUnit class.

long minutes = ChronoUnit.MINUTES.between(first, second);

Upvotes: 9

Tagir Valeev
Tagir Valeev

Reputation: 100339

As Java-8 introduced lambdas and method references, having dedicated Comparator classes became mostly unnecessary, so they are absent in java.time. You may write instead:

Comparator<ZonedDateTime> comparator = Comparator.comparing(
      zdt -> zdt.truncatedTo(ChronoUnit.MINUTES));

Complete example:

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd-MMM-yyyy hh:mm:ss:SSS a X")
        .withLocale(Locale.ENGLISH).withZone(ZoneId.of("Asia/Kolkata"));
ZonedDateTime first = ZonedDateTime.parse("16-Feb-2012 12:03:45:999 AM +0530", formatter);
ZonedDateTime second = ZonedDateTime.parse("16-Feb-2012 12:03:55:999 AM +0530", formatter);
Comparator<ZonedDateTime> comparator = Comparator.comparing(
        zdt -> zdt.truncatedTo(ChronoUnit.MINUTES));
System.out.println(comparator.compare(first, second));

Upvotes: 18

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