Java Date-Time API

JDK Tutorials - Herong's Tutorial Examples

∟Java Date-Time API

This chapter provides tutorial notes and example codes the Date-Time API. Topics include introduction of the java.time package; classes representing moments of time in Epoch seconds or in ISO 8601 calendar date and time fields; classes representing duration of time in seconds and calendar periods in years, months and days.

What Is Date-Time API

java.time.Instant - Representing a Moment of Time

java.time.Instant Usage Examples

java.time.Instant - get(INSTANT_SECONDS) Error

Converting java.util.Date to java.time.Instant

java.time.ZonedDateTime - Calendar and Timezone

java.time.ZonedDateTime Usage Examples

Converting java.util.GregorianCalendar to java.time.ZonedDateTime

java.time.OffsetDateTime - Calendar and UTC Offset

java.time.OffsetDateTime Usage Examples

java.time.LocalDateTime - Local Date and time without Timezone

Partial Date and Time Objects and Classes

java.time.format.DateTimeFormatter - Date-Time Strings

java.time.Duration - Time Durations

java.time.Duration Usage Examples

java.time.Period - Periods in Days and Months

java.time.Period Usage Examples

Conclusion:

Classes of the Date-Time API introduced in Java 8 are better designed than old classes: java.util.Date and java.util.GregorianCalendar.
The java.time.Instant class is replacing the old java.util.Date class to represent a moment of time expressed in Epoch seconds and a fraction.
The java.time.ZonedDateTime class is replacing the old java.util.GregorianCalendar class to represent a moment of time expressed in ISO 8601 calendar date and time fields, including timezone id and UTC offset. The java.time.ZonedDateTime class follows a specific timezone id and respects its daylight saving time rules.
The java.time.OffsetDateTime class also represents a moment of time similar to the java.time.ZonedDateTime class. It expresses the moment of time in ISO 8601 calendar date and time fields, including UTC offset without timezone id.
java.time.LocalDateTime, java.time.LocalDate, java.time.LocalTime and other similar classes represent local date and/or time with a partial list of fields. They cannot be used to precisely represent any moments of time.
The java.time.Duration class represents time durations expressed in seconds and fractions of second. It can be used to manipulate time differences between two moments of time.
The java.time.Period class represents calendar periods expressed in years, months and/or days. It can be used to manipulate differences between two ISO 8601 calendar dates.