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Hello, I’m Xiao Xu Zhu. A few days ago, a fan asked me if I could sort out the new date and time API (jsr-310) for JAVA8. The answer is yes, I’m a fan. Because the content is partial, will tear down many to write.

So much for the gossip, please look at the text below.

An introduction to the commonly used date and time apis

This section describes the datetime apis commonly used by the java8API, in order of java.time package classes:

• Clock, the Clock
• Instant: Instant time.
• LocalDate: indicates the LocalDate. Only year month day
• LocalDateTime: indicates the LocalDate and time. LocalDate+LocalTime
• LocalTime: indicates the LocalTime
• OffsetDateTime: date time with time offset (not including ZoneRegion based time offset)
• OffsetTime: Indicates the time with time offset
• ZonedDateTime: date time with time offset (including ZoneRegion based time offset)

The blogger clicked on all of these classes, which are immutable. It is also officially stated that classes in the java.time package are thread-safe.

Clock

Clock class description

public abstract class Clock {... }Copy the code

Clock is an abstract class that provides four inner classes, which are its internal implementation classes

• FixedClock: A clock that always returns the same moment, often used for testing.
• OffsetClock: indicates the OffsetClock, in the unit of Duration.
• SystemClock: indicates the default local clock.
• TickClock: indicates the offset clock in nanosecond.

Clock provides the following common methods (which have corresponding implementations in the implementation class) :

// Get the current Instant object of the clock. Public abstract Instant Instant () public long millis() public long millis() // Gets the time zone used to create the clock. Public abstract Clock withZone(ZoneId zone) public abstract Clock withZone(ZoneId zone)Copy the code

FixedClock

Clock.fixed

public static Clock fixed(Instant fixedInstant, ZoneId zone)
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Instant and zone need to be passed, and a clock with a fixed instant will be returned.

		Instant instant = Instant.now();
		Clock fixedClock = Clock.fixed(instant, ZoneId.of("Asia/Shanghai"));
		Clock fixedClock1 = Clock.fixed(instant, ZoneId.of("GMT"));
		System.out.println(Chinese time zone Clock:+fixedClock);
		System.out.println("GMT Clock:"+fixedClock1);
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According to the run result, the returned result has the corresponding time zone.

Verify that the acquired clock will not change:

		Clock clock = Clock.systemDefaultZone();
		Clock fixedClock = Clock.fixed(clock.instant(), ZoneId.of("Asia/Shanghai"));
		System.out.println(fixedClock.instant());
		try {
			Thread.sleep(1000);
		} catch (InterruptedException e) {
			e.printStackTrace();
		}
		System.out.println(fixedClock.instant());
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Clock.fixed Creates a fixed Clock. The Clock object will always provide the same time as specified. As shown in the picture, sleep is forced for 1 second, but the time does not change.

Fixed is more compatible with the Offset method

C) clock. fixed d) adding time or subtracting time

Sample code is as follows

		Clock clock = Clock.systemDefaultZone();
		Clock fixedClock = Clock.fixed(clock.instant(), ZoneId.of("Asia/Shanghai"));
		System.out.println(fixedClock.instant());
		Clock clockAdd = Clock.offset(clock, Duration.ofMinutes(20));
		Clock clockSub = Clock.offset(clock, Duration.ofMinutes(-10));
		System.out.println("Original:" + clock.instant());
		System.out.println("Twenty minutes added:" + clockAdd.instant());
		System.out.println("Ten minutes off:" + clockSub.instant());

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OffsetClock

OffsetClock is the OffsetClock, and the offset is Duration.

//Clock
     public static Clock offset(Clock baseClock, Duration offsetDuration) {
        Objects.requireNonNull(baseClock, "baseClock");
        Objects.requireNonNull(offsetDuration, "offsetDuration");
        if (offsetDuration.equals(Duration.ZERO)) {
            return baseClock;
        }
        return new OffsetClock(baseClock, offsetDuration);
    }
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Offset method returns the OffsetClock instance object

		Clock clock = Clock.systemDefaultZone();
		Clock fixedClock = Clock.fixed(clock.instant(), ZoneId.of("Asia/Shanghai"));
		System.out.println(fixedClock.instant());
		Clock clockAdd = Clock.offset(clock, Duration.ofMinutes(20));
		System.out.println("Original:" + clock.instant());
		System.out.println("Twenty minutes added:" + clockAdd.instant());
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SystemClock

SystemClock is the system’s default local clock.

		Clock clock = Clock.systemDefaultZone();
		System.out.println(clock.millis());
		Clock utc = Clock.systemUTC();
		System.out.println(utc.millis());
		System.out.println(System.currentTimeMillis());
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It’s exactly the same. This is to see the source code

Clock.systemDefaultZone()

Use the system’s default time zone zoneid.systemDefault ()

    public static Clock systemDefaultZone() {
        return new SystemClock(ZoneId.systemDefault());
    }
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The final call is also system.CurrentTimemillis ()

Clock.systemUTC()

The UTC time zone is zoneoffset.UTC

    public static Clock systemUTC(a) {
        return new SystemClock(ZoneOffset.UTC);
    }
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The final call is also system.CurrentTimemillis ()

conclusion

The millis() timestamp obtained by clock. systemDefaultZone() is the same as that obtained by clock. systemUTC().

TickClock

TickClock is an offset clock. The minimum unit of time offset is nanosecond.

As you can see, Clock provides three main methods

// The time unit of the constructed clock is a custom offset unit
public static Clock tick(Clock baseClock, Duration tickDuration);
 // The clock is constructed in minutes
 public static Clock tickMinutes(ZoneId zone);
// The clock is constructed in seconds
public static Clock tickSeconds(ZoneId zone) ;
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Practical:

		Clock tickClock = Clock.tick(Clock.systemDefaultZone(),Duration.ofHours(1L));
		Clock tickMinutes = Clock.tickMinutes(ZoneId.of("Asia/Shanghai"));
		Clock tickSeconds = Clock.tickSeconds(ZoneId.of("Asia/Shanghai"));

		LocalDateTime tickClockLocalDateTime = LocalDateTime.ofInstant(Instant.ofEpochMilli(tickClock.millis()),ZoneId.of("Asia/Shanghai"));
		LocalDateTime tickMinutesLocalDateTime = LocalDateTime.ofInstant(Instant.ofEpochMilli(tickMinutes.millis()),ZoneId.of("Asia/Shanghai"));
		LocalDateTime tickSecondsLocalDateTime = LocalDateTime.ofInstant(Instant.ofEpochMilli(tickSeconds.millis()),ZoneId.of("Asia/Shanghai"));

		System.out.println("tickClock :"+tickClock.millis() +"Convert to date time:"+tickClockLocalDateTime);
		System.out.println("tickMinutes:"+tickMinutes.millis() +"Convert to date time:"+tickMinutesLocalDateTime);
		System.out.println("tickSeconds:"+tickSeconds.millis() +"Convert to date time:"+tickSecondsLocalDateTime);
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Offset units supported: days, hours, minutes, seconds, haoseconds, nanoseconds

Instant

Instant class description

public final class Instant
        implements Temporal.TemporalAdjuster.Comparable<Instant>, Serializable {... }Copy the code

Instant means Instant time. Is also immutable and thread-safe. The java.time package is actually thread-safe.

Instant is a new feature in Java 8 with two core fields

.private final long seconds;
    
    private final intnanos; .Copy the code

One is a timestamp in seconds and the other is a timestamp in nanoseconds.

** System.currentTimemillis () returns a millisecond timestamp, while system.currentTimemillis () returns a millisecond timestamp.

Instant Common usage

 		Instant now = Instant.now();
		System.out.println("now:"+now);
		System.out.println(now.getEpochSecond()); / / SEC.
		System.out.println(now.toEpochMilli()); / / ms
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Instant does not have a time zone, but with time zone added Instant can be converted to ZonedDateTime

		Instant ins = Instant.now();
		ZonedDateTime zdt = ins.atZone(ZoneId.systemDefault());
		System.out.println(zdt);
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The long timestamp goes to Instant

Note that the time unit of the long timestamp is the method transformation corresponding to Instant

//1626796436 is a second-level timestamp
Instant ins = Instant.ofEpochSecond(1626796436);
ZonedDateTime zdt = ins.atZone(ZoneId.systemDefault());
System.out.println("Second timestamp conversion:"+zdt);
//1626796436111l is a second-level timestamp
Instant ins1 = Instant.ofEpochMilli(1626796436111l);
ZonedDateTime zdt1 = ins1.atZone(ZoneId.systemDefault());
System.out.println("Millisecond timestamp conversion:"+zdt1);
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The pit of Instant

Instant. Now () is 8 time zones different from Beijing time. This is a detail to avoid.

Look at the source code, in UTC time.

public static Instant now(a) {
        return Clock.systemUTC().instant();
    }
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Solution:

Instant now = Instant.now().plusMillis(TimeUnit.HOURS.toMillis(8));
System.out.println("now:"+now);
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LocalDate

LocalDate class description

LocalDate indicates the LocalDate. Only year month day. The value is equivalent to YYYY-MM-DD.

Common usage of LocalDate

Get the current date

		LocalDate localDate1 = LocalDate.now();
		LocalDate localDate2 = LocalDate.now(ZoneId.of("Asia/Shanghai"));
		LocalDate localDate3 = LocalDate.now(Clock.systemUTC());

		System.out.println("now :"+localDate1);
		System.out.println("now by zone :"+localDate2);
		System.out.println("now by Clock:"+localDate3);
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Get the localDate object

		LocalDate localDate1 = LocalDate.of(2021.8.14);
		LocalDate localDate2 = LocalDate.parse("2021-08-14");
		System.out.println(localDate1);
		System.out.println(localDate2);
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Gets the year, month and day of the specified date

LocalDate localDate1 = LocalDate.of(2021, 8, 14); // Current date year: 2021 System.out.println(localDate1.getYear()); AUGUST System.out.println(localDate1.getMonth())); Println (localDatE1.getMonthValue ()); // Current month: 8 System.out.println(localDate1.getMonthValue()); // The date is the day of the current week :6 system.out.println (localDate1.getDayofweek ().getValue()); // The date is the day of the current month :14 system.out.println (localDate1.getDayofMonth ()); // The date is the day of the current year :226 system.out.println (localDate1.getDayofYear ());Copy the code

Modify the year, month and day

		LocalDate localDate1 = LocalDate.of(2021.8.14);
		// Modify the year of the date: 2022-08-14
		System.out.println(localDate1.withYear(2022));
		// Modify the date month: 2021-12-14
		System.out.println(localDate1.withMonth(12));
		// Change the number of days in the current month: 2021-08-01
		System.out.println(localDate1.withDayOfMonth(1));
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Comparing the date

LocalDate localDate1 = LocalDate.of(2021, 8, 14); Int I = localDate1.compareTo(localdate.of (2021, 8, 1)); System.out.println(i); Println (localdate1.isbefore (localdate.of (2021,8,31))); Println (localdate1.isafter (localdate.of (2021,8,31))); false system.out.println (localdate1.isafter (localdate.of (2021,8,31)); Println (localDate1.isequal (localDate.of (2021, 8, 14)));Copy the code

LocalDate and String convert to each other, and Date and LocalDate convert to each other

LocalDate and String convert to each other

		LocalDate localDate1 = LocalDate.of(2021.8.14);
		/ / LocalDate String
		DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy-MM-dd");
		String dateString = localDate1.format(dateTimeFormatter);
		System.out.println("Turn LocalDate String."+dateString);
		/ / String LocalDate
		String str = "2021-08-14";
		DateTimeFormatter fmt = DateTimeFormatter.ofPattern("yyyy-MM-dd");
		LocalDate date = LocalDate.parse(str, fmt);
		System.out.println("String turned LocalDate:"+date);
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Date and LocalDate are converted to each other

	/ / Date LocalDate
		Date now = new Date();
		// Convert Date to ZonedDateTime
		Instant instant = now.toInstant();
		ZonedDateTime zonedDateTime = instant.atZone(ZoneId.of("Asia/Shanghai"));
		LocalDate localDate = zonedDateTime.toLocalDate();
		// Sat Aug 14 23:16:28 CST 2021
		System.out.println(now);
		/ / 2021-08-14
		System.out.println(localDate);

		/ / LocalDate Date
		LocalDate now1 = LocalDate.now();
		ZonedDateTime dateTime = now1.atStartOfDay(ZoneId.of("Asia/Shanghai"));
		Date date1 = Date.from(dateTime.toInstant());
		System.out.println(date1);
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LocalDateTime

LocalDateTime class description

Indicates the current date and time. The value is yyyY-MM-DDTHh: MM :ss

Common usage of LocalDateTime

Gets the current date and time

		LocalDate d = LocalDate.now(); // The current date
		LocalTime t = LocalTime.now(); // The current time
		LocalDateTime dt = LocalDateTime.now(); // Current date and time
		System.out.println(d); // Print strictly in ISO 8601 format
		System.out.println(t); // Print strictly in ISO 8601 format
		System.out.println(dt); // Print strictly in ISO 8601 format
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The local date and time retrieved from now() is always returned with the current default time zone, depending on the run result

Gets the specified date and time

		LocalDate d2 = LocalDate.of(2021.07.14); // 2021-07-14, note that 07=07 months
		LocalTime t2 = LocalTime.of(13.14.20); / / 13:14:20
		LocalDateTime dt2 = LocalDateTime.of(2021.07.14.13.14.20);
		LocalDateTime dt3 = LocalDateTime.of(d2, t2);
		System.out.println("Specified date and time:"+dt2);
		System.out.println("Specified date and time:"+dt3);
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Date and time addition and subtraction and modification

		LocalDateTime currentTime = LocalDateTime.now(); // Current date and time
		System.out.println("-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- time addition and subtraction and modification -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --");
		//3.LocalDateTime addition and subtraction include all LocalDate and LocalTime additions and subtractions
		System.out.println("3. Current time:" + currentTime);
		System.out.println("3. Current time plus 5 years:" + currentTime.plusYears(5));
		System.out.println("3. Current time plus 2 months:" + currentTime.plusMonths(2));
		System.out.println("3. Current time minus 2 days:" + currentTime.minusDays(2));
		System.out.println("3. Current time minus 5 hours:" + currentTime.minusHours(5));
		System.out.println("3. Current time plus 5 minutes:" + currentTime.plusMinutes(5));
		System.out.println("3. Current time plus 20 seconds:" + currentTime.plusSeconds(20));
		// Add a year back, subtract a day forward, add 2 hours back, subtract 5 minutes forward
		System.out.println("3. At the same time (add one year back, subtract one day forward, add two hours back, subtract five minutes forward) :" + currentTime.plusYears(1).minusDays(1).plusHours(2).minusMinutes(5));
		System.out.println("3. Modified year to 2025:" + currentTime.withYear(2025));
		System.out.println("3. Modify month to December:" + currentTime.withMonth(12));
		System.out.println("3. Modification date: 27th:" + currentTime.withDayOfMonth(27));
		System.out.println("3. Change the hour to 12:" + currentTime.withHour(12));
		System.out.println("3. Change the minutes to 12:" + currentTime.withMinute(12));
		System.out.println("3. Change the seconds to 12:" + currentTime.withSecond(12));
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LocalDateTime and Date are converted to each other

Turn the Date LocalDateTime

		System.out.println("-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- method one: write step by step -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --");
		// Instantiate a time object
		Date date = new Date();
		// Returns the instant representing the same point on the timeline as the date object
		Instant instant = date.toInstant();
		// Obtain the default system time zone
		ZoneId zoneId = ZoneId.systemDefault();
		// Get the date and time with time zone based on time zone
		ZonedDateTime zonedDateTime = instant.atZone(zoneId);
		// Convert to LocalDateTime
		LocalDateTime localDateTime = zonedDateTime.toLocalDateTime();
		System.out.println("Method 1: Date =" + date);
		System.out.println(Method 1: LocalDateTime =" + localDateTime);

		System.out.println("-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- method 2: one pace reachs the designated position (recommended) -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --");
		// Instantiate a time object
		Date todayDate = new Date();
		// instant.ofepochmilli (long L) uses milliseconds in epoch 1970-01-01t00:00:00 Z to get an instance of Instant
		LocalDateTime ldt = Instant.ofEpochMilli(todayDate.getTime()).atZone(ZoneId.systemDefault()).toLocalDateTime();
		System.out.println(Date = Date = Date + todayDate);
		System.out.println("LocalDateTime =" + ldt);
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LocalDateTime transfer Date

		System.out.println("-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- method one: write step by step -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --");
		// Get LocalDateTime, the current time
		LocalDateTime localDateTime = LocalDateTime.now();
		// Obtain the default system time zone
		ZoneId zoneId = ZoneId.systemDefault();
		// Get the date and time with time zone based on time zone
		ZonedDateTime zonedDateTime = localDateTime.atZone(zoneId);
		// Returns the instant representing the same point on the timeline as the date object
		Instant instant = zonedDateTime.toInstant();
		// Convert to Date
		Date date = Date.from(instant);
		System.out.println(LocalDateTime = LocalDateTime + localDateTime);
		System.out.println("Method 1: Convert Date =" + date);

		System.out.println("-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- method 2: one pace reachs the designated position (recommended) -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --");
		Instantiate a LocalDateTime object
		LocalDateTime now = LocalDateTime.now();
		// Convert to date
		Date dateResult = Date.from(now.atZone(ZoneId.systemDefault()).toInstant());
		System.out.println(LocalDateTime = LocalDateTime + now);
		System.out.println("Method 2: Convert Date =" + dateResult);
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LocalTime

LocalTime class description

LocalTime: indicates the LocalTime

Common usage of LocalTime

Get the current time

		LocalTime localTime1 = LocalTime.now();
		LocalTime localTime2 = LocalTime.now(ZoneId.of("Asia/Shanghai"));
		LocalTime localTime3 = LocalTime.now(Clock.systemDefaultZone());

		System.out.println("now :"+localTime1);
		System.out.println("now by zone :"+localTime2);
		System.out.println("now by Clock:"+localTime3);
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Get the LocalTime object

		LocalTime localTime1 = LocalTime.of(23.26.30);
		LocalTime localTime2 = LocalTime.of(23.26);
		System.out.println(localTime1);
		System.out.println(localTime2);
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Gets the time and second of the specified date

		LocalTime localTime1 = LocalTime.of(23.26.30);
		// Current time: 23
		System.out.println(localTime1.getHour());
		// The current time is 26 minutes
		System.out.println(localTime1.getMinute());
		// The current time in seconds: 30
		System.out.println(localTime1.getSecond());
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Change time minute second

		LocalTime localTime1 = LocalTime.of(23.26.30);
		// Change time: 00:26:30
		System.out.println(localTime1.withHour(0));
		// Change the minute of the time: 23:30:30
		System.out.println(localTime1.withMinute(30));
		// Change the time in seconds: 23:26:59
		System.out.println(localTime1.withSecond(59));
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More time

		LocalTime localTime1 = LocalTime.of(23.26.30);
		LocalTime localTime2 = LocalTime.of(23.26.32);
		// Return 0:-1; // Return 0:-1
		System.out.println(localTime1.compareTo(localTime2));

		// Compares whether the specified time is earlier than the parameter time (true is earlier) :true
		System.out.println(localTime1.isBefore(localTime2));
		// Compares whether the specified time is later than the parameter time (true is later) :false
		System.out.println(localTime1.isAfter(localTime2));
		// Compare whether two times are equal :true
		System.out.println(localTime1.equals(LocalTime.of(23.26.30)));
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OffsetDateTime

OffsetDateTime class description

OffsetDateTime: date time with time offset (not including ZoneRegion based time offset)

public final class OffsetDateTime
        implements Temporal.TemporalAdjuster.Comparable<OffsetDateTime>, Serializable {
    //The minimum supported {@code OffsetDateTime}, '-999999999-01-01T00:00:00+18:00' 
    public static final OffsetDateTime MIN = LocalDateTime.MIN.atOffset(ZoneOffset.MAX);
    // The maximum supported {@code OffsetDateTime}, '+ 9999999-12-31T23:59:59.9999999-18:00 '.
    public static finalOffsetDateTime MAX = LocalDateTime.MAX.atOffset(ZoneOffset.MIN); . }Copy the code

MIN and MAX above are public static variables.

OffsetDateTime Common usage

Gets the current date and time

		OffsetDateTime offsetDateTime1 = OffsetDateTime.now();
		OffsetDateTime offsetDateTime2 = OffsetDateTime.now(ZoneId.of("Asia/Shanghai"));
		OffsetDateTime offsetDateTime3 = OffsetDateTime.now(Clock.systemUTC());

		System.out.println("now :"+offsetDateTime1);
		System.out.println("now by zone :"+offsetDateTime2);
		System.out.println("now by Clock:"+offsetDateTime3);
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Gets the OffsetDateTime object

		LocalDateTime localDateTime1 = LocalDateTime.of(2021.8.15.13.14.20);
		OffsetDateTime offsetDateTime1 = OffsetDateTime.of(localDateTime1, ZoneOffset.ofHours(8));
		OffsetDateTime offsetDateTime2 = OffsetDateTime. of(2021.8.15.13.14.20.0, ZoneOffset.ofHours(8));
		Instant now = Instant.now();
		OffsetDateTime offsetDateTime3 = OffsetDateTime.ofInstant(now, ZoneId.of("Asia/Shanghai"));

		System.out.println(offsetDateTime1);
		System.out.println(offsetDateTime2);
		System.out.println(offsetDateTime3);
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Gets the year, month, day, hour, minute, second of the specified date

		LocalDateTime localDateTime1 = LocalDateTime.of(2021.8.15.13.14.20);
		OffsetDateTime offsetDateTime1 = OffsetDateTime.of(localDateTime1, ZoneOffset.ofHours(8));
		// Current year: 2021
		System.out.println(offsetDateTime1.getYear());
		// Month of the current time: 8
		System.out.println(offsetDateTime1.getMonthValue());
		// Date of current time: 15
		System.out.println(offsetDateTime1.getDayOfMonth());
		// Current time: 13
		System.out.println(offsetDateTime1.getHour());
		// The current time is 14 minutes
		System.out.println(offsetDateTime1.getMinute());
		// The current time in seconds: 20
		System.out.println(offsetDateTime1.getSecond());
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Modify the year, month, day, hour, minute, second

		LocalDateTime localDateTime1 = LocalDateTime.of(2021.8.15.13.14.20);
		OffsetDateTime offsetDateTime1 = OffsetDateTime.of(localDateTime1, ZoneOffset.ofHours(8));
		// Modify time year: 2022-08-15T13:14:20+08:00
		System.out.println(offsetDateTime1.withYear(2022));
		// Modify time month: 2021-09-15T13:14:20+08:00
		System.out.println(offsetDateTime1.withMonth(9));
		// Date of modification: 2021-08-30T13:14:20+08:00
		System.out.println(offsetDateTime1.withDayOfMonth(30));
		// Modify time: 2021-08-15T00:14:20+08:00
		System.out.println(offsetDateTime1.withHour(0));
		// Modify time: 2021-08-15T13:30:20+08:00
		System.out.println(offsetDateTime1.withMinute(30));
		// Modify time in seconds: 2021-08-15T13:14:59+08:00
		System.out.println(offsetDateTime1.withSecond(59));
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Compare date and time

		LocalDateTime localDateTime1 = LocalDateTime.of(2021.8.15.13.14.20);
		OffsetDateTime offsetDateTime1 = OffsetDateTime.of(localDateTime1, ZoneOffset.ofHours(8));
		OffsetDateTime offsetDateTime3 = OffsetDateTime.of(localDateTime1, ZoneOffset.ofHours(8));

		LocalDateTime localDateTime2 = LocalDateTime.of(2021.8.15.13.14.30);
		OffsetDateTime offsetDateTime2 = OffsetDateTime.of(localDateTime2, ZoneOffset.ofHours(8));

		// Return 0:-1; // Return 0:-1
		System.out.println(offsetDateTime1.compareTo(offsetDateTime2));

		// Compares whether the specified time is earlier than the parameter time (true is earlier) :true
		System.out.println(offsetDateTime1.isBefore(offsetDateTime2));
		// Compares whether the specified time is later than the parameter time (true is later) :false
		System.out.println(offsetDateTime1.isAfter(offsetDateTime2));
		// Compare whether two times are equal :true
		System.out.println(offsetDateTime1.equals(offsetDateTime3));
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The string is converted to an OffsetDateTime object

				String str = "2021-08-15T10:15:30+08:00";
		OffsetDateTime offsetDateTime1 = OffsetDateTime.parse(str);
		OffsetDateTime offsetDateTime2 = OffsetDateTime.parse(str,DateTimeFormatter.ISO_OFFSET_DATE_TIME);

		System.out.println(offsetDateTime1);
		System.out.println(offsetDateTime2);
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OffsetTime

OffsetTime class description

OffsetTime: Indicates the time with time offset

public final class OffsetTime
        implements Temporal.TemporalAdjuster.Comparable<OffsetTime>, Serializable {
   //The minimum supported {@code OffsetTime}, '00:00:00+18:00'.
    public static final OffsetTime MIN = LocalTime.MIN.atOffset(ZoneOffset.MAX);
    
    //The maximum supported {@code OffsetTime}, '23:59:59.9999999-18:00 '.
    public static finalOffsetTime MAX = LocalTime.MAX.atOffset(ZoneOffset.MIN); . }Copy the code

MIN and MAX above are public static variables.

OffsetTime Common usage

Get the current time

		OffsetTime offsetTime1 = OffsetTime.now();
		OffsetTime offsetTime2 = OffsetTime.now(ZoneId.of("Asia/Shanghai"));
		OffsetTime offsetTime3 = OffsetTime.now(Clock.systemUTC());

		System.out.println("now :"+offsetTime1);
		System.out.println("now by zone :"+offsetTime2);
		System.out.println("now by Clock:"+offsetTime3);
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Gets the OffsetTime object

		LocalTime localTime1 = LocalTime.of(13.14.20);
		OffsetTime offsetTime1 = OffsetTime.of(localTime1, ZoneOffset.ofHours(8));
		OffsetTime offsetTime2 = OffsetTime. of(13.14.20.0, ZoneOffset.ofHours(8));
		Instant now = Instant.now();
		OffsetTime offsetTime3 = OffsetTime.ofInstant(now, ZoneId.of("Asia/Shanghai"));

		System.out.println(offsetTime1);
		System.out.println(offsetTime2);
		System.out.println(offsetTime3);
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Gets the hour and second of the specified time

		LocalTime localTime1 = LocalTime.of( 13.14.20);
		OffsetTime offsetTime1 = OffsetTime.of(localTime1, ZoneOffset.ofHours(8));

		// Current time: 13
		System.out.println(offsetTime1.getHour());
		// The current time is 14 minutes
		System.out.println(offsetTime1.getMinute());
		// The current time in seconds: 20
		System.out.println(offsetTime1.getSecond());
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Change time minute second

		LocalTime localTime1 = LocalTime.of( 13.14.20);
		OffsetTime offsetTime1 = OffsetTime.of(localTime1, ZoneOffset.ofHours(8));

		// Change time: 00:14:20+08:00
		System.out.println(offsetTime1.withHour(0));
		// Change the time of the minute: 13:30:20+08:00
		System.out.println(offsetTime1.withMinute(30));
		// Change the time in seconds: 13:14:59+08:00
		System.out.println(offsetTime1.withSecond(59));
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More time

		LocalTime localTime1 = LocalTime.of( 13.14.20);
		OffsetTime offsetTime1 = OffsetTime.of(localTime1, ZoneOffset.ofHours(8));
		OffsetTime offsetTime3 = OffsetTime.of(localTime1, ZoneOffset.ofHours(8));

		LocalTime localTime2 = LocalTime.of(13.14.30);
		OffsetTime offsetTime2 = OffsetTime.of(localTime2, ZoneOffset.ofHours(8));
		// Return 0:-1; // Return 0:-1
		System.out.println(offsetTime1.compareTo(offsetTime2));

		// Compares whether the specified time is earlier than the parameter time (true is earlier) :true
		System.out.println(offsetTime1.isBefore(offsetTime2));
		// Compares whether the specified time is later than the parameter time (true is later) :false
		System.out.println(offsetTime1.isAfter(offsetTime2));
		// Compare whether two times are equal :true
		System.out.println(offsetTime1.equals(offsetTime3));
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ZonedDateTime

ZonedDateTime class description

Represents a date and time with a time zone. ZonedDateTime can be interpreted as LocalDateTime+ZoneId

ZonedDateTime class defines LocalDateTime and ZoneId variables.

The ZonedDateTime class is also immutable and thread-safe.

public final class ZonedDateTime
        implements Temporal.ChronoZonedDateTime<LocalDate>, Serializable {

    /** * Serialization version. */
    private static final long serialVersionUID = -6260982410461394882L;

    /** * The local date-time. */
    private final LocalDateTime dateTime;
    /** * The time-zone. */
    private finalZoneId zone; . }Copy the code

ZonedDateTime Common usage

Gets the current date and time

		// Default time zone Obtains the current time
		ZonedDateTime zonedDateTime = ZonedDateTime.now();
		// Obtain the current time with the specified time zone. Asia/Shanghai is the Shanghai time zone
		ZonedDateTime zonedDateTime1 = ZonedDateTime.now(ZoneId.of("Asia/Shanghai"));
		//withZoneSameInstant is the conversion time zone. The parameter is ZoneId
		ZonedDateTime zonedDateTime2 = zonedDateTime.withZoneSameInstant(ZoneId.of("America/New_York"));
		System.out.println(zonedDateTime);
		System.out.println(zonedDateTime1);
		System.out.println(zonedDateTime2);
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		ZonedDateTime zonedDateTime1 = ZonedDateTime.now();
		ZonedDateTime zonedDateTime2 = ZonedDateTime.now(ZoneId.of("Asia/Shanghai"));
		ZonedDateTime zonedDateTime3 = ZonedDateTime.now(Clock.systemUTC());

		System.out.println("now :"+zonedDateTime1);
		System.out.println("now by zone :"+zonedDateTime2);
		System.out.println("now by Clock:"+zonedDateTime3);
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Get the ZonedDateTime object

		LocalDateTime localDateTime1 = LocalDateTime.of(2021.8.15.13.14.20);
		ZonedDateTime zonedDateTime1 = ZonedDateTime.of(localDateTime1, ZoneOffset.ofHours(8));
		ZonedDateTime zonedDateTime2 = ZonedDateTime. of(2021.8.15.13.14.20.0, ZoneOffset.ofHours(8));
		Instant now = Instant.now();
		ZonedDateTime zonedDateTime3 = ZonedDateTime.ofInstant(now, ZoneId.of("Asia/Shanghai"));

		System.out.println(zonedDateTime1);
		System.out.println(zonedDateTime2);
		System.out.println(zonedDateTime3);
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Gets the year, month, day, hour, minute, second of the specified date

		LocalDateTime localDateTime1 = LocalDateTime.of(2021.8.15.13.14.20);
		ZonedDateTime zonedDateTime1 = ZonedDateTime.of(localDateTime1, ZoneOffset.ofHours(8));
		// Current year: 2021
		System.out.println(zonedDateTime1.getYear());
		// Month of the current time: 8
		System.out.println(zonedDateTime1.getMonthValue());
		// Date of current time: 15
		System.out.println(zonedDateTime1.getDayOfMonth());
		// Current time: 13
		System.out.println(zonedDateTime1.getHour());
		// The current time is 14 minutes
		System.out.println(zonedDateTime1.getMinute());
		// The current time in seconds: 20
		System.out.println(zonedDateTime1.getSecond());
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Modify the year, month, day, hour, minute, second

		LocalDateTime localDateTime1 = LocalDateTime.of(2021.8.15.13.14.20);
		ZonedDateTime zonedDateTime1 = ZonedDateTime.of(localDateTime1, ZoneOffset.ofHours(8));
		// Modify time year: 2022-08-15T13:14:20+08:00
		System.out.println(zonedDateTime1.withYear(2022));
		// Modify time month: 2021-09-15T13:14:20+08:00
		System.out.println(zonedDateTime1.withMonth(9));
		// Date of modification: 2021-08-30T13:14:20+08:00
		System.out.println(zonedDateTime1.withDayOfMonth(30));
		// Modify time: 2021-08-15T00:14:20+08:00
		System.out.println(zonedDateTime1.withHour(0));
		// Modify time: 2021-08-15T13:30:20+08:00
		System.out.println(zonedDateTime1.withMinute(30));
		// Modify time in seconds: 2021-08-15T13:14:59+08:00
		System.out.println(zonedDateTime1.withSecond(59));
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Compare date and time

		LocalDateTime localDateTime1 = LocalDateTime.of(2021.8.15.13.14.20);
		ZonedDateTime zonedDateTime1 = ZonedDateTime.of(localDateTime1, ZoneOffset.ofHours(8));

		ZonedDateTime zonedDateTime3 = ZonedDateTime.of(localDateTime1, ZoneOffset.ofHours(8));

		LocalDateTime localDateTime2 = LocalDateTime.of(2021.8.15.13.14.30);
		ZonedDateTime zonedDateTime2 = ZonedDateTime.of(localDateTime2, ZoneOffset.ofHours(8));

		// Return 0:-1; // Return 0:-1
		System.out.println(zonedDateTime1.compareTo(zonedDateTime2));

		// Compares whether the specified time is earlier than the parameter time (true is earlier) :true
		System.out.println(zonedDateTime1.isBefore(zonedDateTime2));
		// Compares whether the specified time is later than the parameter time (true is later) :false
		System.out.println(zonedDateTime1.isAfter(zonedDateTime2));
		// Compare whether two times are equal :true
		System.out.println(zonedDateTime1.equals(zonedDateTime3));
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LocalDateTime + ZoneId ZonedDateTime

		LocalDateTime localDateTime = LocalDateTime.now();
		ZonedDateTime zonedDateTime1 = localDateTime.atZone(ZoneId.systemDefault());
		ZonedDateTime zonedDateTime2 = localDateTime.atZone(ZoneId.of("America/New_York"));
		System.out.println(zonedDateTime1);
		System.out.println(zonedDateTime2);
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The above example shows that LocalDateTime can be converted to ZonedDateTime.

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