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3-Core-Java-APIs-Dates.md

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theme: Plain Jane autoscale: true

Dates and Times in Java 8

Current Date

LocalDate now = LocalDate.now();
System.out.println(now);

// 2015-11-08
  • LocalDate: only date (not time)
  • can't do new LocalDate();
  • import java.time.LocalDate;

Date with year, month, day

LocalDate firstOfJanuary2015 = LocalDate.of(2015, Month.JANUARY, 1);
System.out.println(firstOfJanuary2015);

LocalDate inmutable!

LocalDate _12Oct1492_ = LocalDate.of(1492, Month.OCTOBER, 12);
_12Oct1492_.plusDays(800);
System.out.println(_12Oct1492_);								// 1492-10-12
LocalDate other = _12Oct1492_.plusDays(800);
System.out.println(other);										// 1494-12-21

LocalTime

LocalTime timeNow = LocalTime.now();
System.out.println(timeNow);									// 13:51:53.382
  • LocalTime: sólo tiempo
  • LocalDateTime: fecha y hora

LocalTime inmutable!

LocalTime timeNow = LocalTime.now();
System.out.println(timeNow);

timeNow.plusHours(1);
System.out.println(timeNow);

// 19:57:24.995
// 19:57:24.995
  • plusMinutes / minusMinutes
  • plusSeconds / minus

Recorrer intervalos

LocalDate start = LocalDate.of(2015, Month.APRIL, 10);
LocalDate end = LocalDate.of(2015, Month.APRIL, 20);
while (start.isBefore(end)) {
	System.out.println(start);
	start = start.plusDays(1);
}

2015-04-10
2015-04-11
2015-04-12
2015-04-13
2015-04-14
2015-04-15
2015-04-16
2015-04-17
2015-04-18
2015-04-19

TimeZones 1

System.out.println(LocalTime.now());
System.out.println(LocalTime.now(ZoneId.of("US/Pacific")));
System.out.println(LocalTime.now(ZoneId.of("Zulu")));

// console output

20:05:25.170
11:05:25.172
19:05:25.173

Period

// Create task every week

Period everyWeek = Period.ofWeeks(1);
start = LocalDate.now();
end = LocalDate.of(2016, Month.APRIL, 10);
while (start.isBefore(end)) {
	System.out.println(start);
	start = start.plus(everyWeek);
}

Parse dates

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy/MM/dd");
LocalDate date = LocalDate.parse("2010/10/40", formatter);
System.out.println(date);
  • can throw java.time.format.DateTimeParseException (Runtime)

Footnotes

  1. no entra en el examen https://garygregory.wordpress.com/2013/06/18/what-are-the-java-timezone-ids/ ↩