java-time – Make Me Engineer

How can I parse/format dates with LocalDateTime? (Java 8)

Parsing date and time To create a LocalDateTime object from a string you can use the static LocalDateTime.parse() method. It takes a string and a DateTimeFormatter as parameter. The DateTimeFormatter is used to specify the date/time pattern. String str = “1986-04-08 12:30”; DateTimeFormatter formatter = DateTimeFormatter.ofPattern(“yyyy-MM-dd HH:mm”); LocalDateTime dateTime = LocalDateTime.parse(str, formatter); Formatting date and … Read more

How to persist JSR-310 types with Spring Data JPA?

UPDATE: The answer below is valid if you need to stay on a Hibernate version < 5.0. Hibernate 5.0 supports persisting JSR-310 date/time types out of the box. I.e. if you are on Hibernate 5.0 or newer, Adam’s answer is the way to go. Everyone else, read on. The root cause for this at none … Read more

Can’t parse String to LocalDate (Java 8)

For year you have to use the lowercase y: final DateTimeFormatter DATE_FORMAT = DateTimeFormatter.ofPattern(“dd-MM-yyyy”); Uppercase Y is used for weekyear. See the javadoc of DateTimeFormatter for more details.

DateTimeFormatter month pattern letter “L” fails

“stand-alone” month name I believe ‘L’ is meant for languages that use a different word for the month itself versus the way it is used in a date. For example: Locale russian = Locale.forLanguageTag(“ru”); asList(“MMMM”, “LLLL”).forEach(ptrn -> System.out.println(ptrn + “: ” + ofPattern(ptrn, russian).format(Month.MARCH)) ); Output: MMMM: марта LLLL: Март There shouldn’t be any reason … Read more

How to round time to the nearest quarter hour in java?

Rounding You will need to use modulo to truncate the quarter hour: Date whateverDateYouWant = new Date(); Calendar calendar = Calendar.getInstance(); calendar.setTime(whateverDateYouWant); int unroundedMinutes = calendar.get(Calendar.MINUTE); int mod = unroundedMinutes % 15; calendar.add(Calendar.MINUTE, mod < 8 ? -mod : (15-mod)); As pointed out by EJP, this is also OK (replacement for the last line, only … Read more

Convert between LocalDate and sql.Date [duplicate]

The Java 8 version (and later) of java.sql.Date has built in support for LocalDate, including toLocalDate and valueOf(LocalDate). To convert from LocalDate to java.sql.Date you can use java.sql.Date.valueOf( localDate ); And to convert from java.sql.Date to LocalDate: sqlDate.toLocalDate(); Time zones: The LocalDate type stores no time zone information, while java.sql.Date does. Therefore, when using the … Read more

How to use LocalDateTime RequestParam in Spring? I get “Failed to convert String to LocalDateTime”

TL;DR – you can capture it as a string with just @RequestParam, or you can have Spring additionally parse the string into a java date / time class via @DateTimeFormat on the parameter as well. the @RequestParam is enough to grab the date you supply after the = sign, however, it comes into the method … Read more

LocalDate to java.util.Date and vice versa simplest conversion? [duplicate]

tl;dr Is there a simple way to convert a LocalDate (introduced with Java 8) to java.util.Date object? By ‘simple’, I mean simpler than this Nope. You did it properly, and as concisely as possible. java.util.Date.from( // Convert from modern java.time class to troublesome old legacy class. DO NOT DO THIS unless you must, to inter … Read more

How to get milliseconds from LocalDateTime in Java 8

I’m not entirely sure what you mean by “current milliseconds” but I’ll assume it’s the number of milliseconds since the “epoch,” namely midnight, January 1, 1970 UTC. If you want to find the number of milliseconds since the epoch right now, then use System.currentTimeMillis() as Anubian Noob has pointed out. If so, there’s no reason … Read more

Unit testing a class with a Java 8 Clock

I don’t want to add a Clock argument to the method because the real code shouldn’t be concerned with passing in a clock. No… but you might want to consider it as a constructor parameter. Basically you’re saying that your class needs a clock with which to work… so that’s a dependency. Treat it as … Read more

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