ch09_datetime

9. DateTime API

• object of java.util.Date has attribute that holds count of seconds from 01-01-1970 01:00:00.000
• Java 8 comes with new API (should be in java.time.* package) inspired by Joda-Time
• objects from new date/time API have attributes as year, month, day, ... with explicit value
• objects of LocalDateTime* NOT contains zoned information - for this purpose should be used ZonedDateTime* classes
• new API provides more new methods, e.g.: format(...), parse(...), now(), ...

Conversion

• java.sql.Date#toLocalDate, resp. java.sql.Time#toLocalTime or java.sql.Timestamp#toLocalDateTime
• from java.util.Date is possible to get object of java.time.Instant and after then use LocalDateTime#ofInstant() (Beware: it provides only LocalDateTime class)

Others

Duration

• class java.time.Duration
• is time-based
• units granularity is nanoseconds .. days
• #between() returns HOURS by default
• #equal() compares only attributes nanos and seconds

Period

• class java.time.Period
• is date-based
• units granularity is days .. years
• #between() returns YEARS by default
• #equal() compares only attributes yaers, months and days

ChronoUnit

• class java.time.temporal.ChronoUnit
• units granularity is nanoseconds .. forever
• it provides easy conversion to Duration which is internally used by ChronoUnit
• see ChronoUnit#getDuration