As noted in your question and in my comment, ZoneRulesProvider.getAvailableZoneIds() creates a new set of all the available time zones’ string representation (the keys of the static final ConcurrentMap<String, ZoneRulesProvider> ZONES) each time a time zone needs to be parsed.1 Fortunately, a ZoneRulesProvider is an abstract class which is designed to be subclassed. The method … Read more
The precision is different because LocalDateTime.now() uses a system default Clock. Obtains the current date-time from the system clock in the default time-zone. This will query the system clock in the default time-zone to obtain the current date-time. … The link in this Javadoc takes you to Clock.systemDefaultZone() which states (emphasis mine): Obtains a clock … Read more
The documentation of LocalDateTime specifies the instance of LocalDateTime is immutable, for example plusHours public LocalDateTime plusHours(long hours) Returns a copy of this LocalDateTime with the specified number of hours added. This instance is immutable and unaffected by this method call. Parameters: hours – the hours to add, may be negative Returns: a LocalDateTime based … Read more
I will go ahead and post an answer based on my final solution and a sort of summary of the very long comment chain. To start, the whole conversion chain of: Date –> Instant –> LocalDateTime –> Do stuff –> Instant –> Date Is necessary to preserve the time zone information and still do operations … Read more
New Methods On Old Classes By using the driver with Java 8 and later, you should automatically pick up some methods on your java.sql.Timestamp object for free. Both java.sql.Time and java.sql.Date have similar conversion methods. Namely, to convert from java.sql to java.time you are looking for: Timestamp::toInstant() Timestamp::toLocalDateTime() Date::toLocalDate() Time::toLocalTime() To go the other direction, … Read more
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.
You have to interpret the Instant at some time zone to get ZonedDateTime. As an Instant measures the ellapsed seconds and nano seconds from epoch 1970-01-01T00:00:00Z you should use UTC to get the same time as the Instant would print. (Z ≙ Zulu Time ≙ UTC) Getting the time Instant instant; // get overall time … Read more
This is what java.time.temporal.TemporalAdjusters are for. date.with(TemporalAdjusters.firstDayOfMonth()).truncatedTo(ChronoUnit.DAYS);
The “Local…” types purposely have no concept of time zone. So they do not represent a moment on the timeline. A LocalDateTime represents a vague range of possible moments but has no real meaning until assigning an offset or time zone. That means applying a ZoneId to get a ZonedDateTime. For example, to say that … Read more
Both are fine. And neither is recommended except for a minority of purposes. What do you need milliseconds since the epoch for? In Java, we can have many different ways to get the current timestamp, For current timestamp just use Instant.now(). No need to convert to milliseconds. Many methods from the first years of Java, … Read more