New Java Date/Time API

INTRODUCTION
TOTHE JAVA 8
DATE AND TIME
API

CLASSES TO
CREATE AND
MANIPULATE
CALENDAR
DATA
•LocalDateTime,
•LocalDate,
•LocalTime,
•DateTimeFormatter

METHOD PREFIXES,TYPES,AND THEIR USES IN THE DATE AND TIME
API IN JAVA 8
Prefixes MethodType Uses
of Static Creates an instance where the factory is
primarily validating the input parameters,
not converting them.
parse static Parses the input string to produce an
instance of the target class.
format instance Uses the specified formatter to format
the values in the temporal object to
produce a string.
get instance Returns a part of the state of the target
object.
plus instance Returns a copy of the target object with
an amount of time added.

WORKING WITH CALENDAR DATA
Create and manipulate calendar
data using classes from Java.time.LocalDateTime Java.time.LocalDate
Java.time.LocalTime
Java.time.format.DateTimeFormat
ter

LocalDate
To store dates like a birthday or anniversary,visiting a place,or starting a job,
school,or college,you don’t need to store the time. LocalDate can be used to
store dates like 2015-12-27 without time or time zones.LocalDate instances are
immutable.
CREATING LOCALDATE
The LocalDate constructor is marked private,so you must use one of the factory
methods to instantiate it.The static method of() accepts year, month,and day of
month:
LocalDate date1 = LocalDate.of(2015,12,27);
LocalDate date2 = LocalDate.of(2015,Month.DECEMBER,27);

LocalDate
To get the current date from the system clock,use the static method now():
LocalDate date3 = LocalDate.now();
You can also parse a string in the format 2016-02-27 to instantiate LocalDate.
Here’s an example:
LocalDate date2 = LocalDate.parse("2025-08-09");

LocalDate
 QUERYING LOCALDATE
You can use instance methods like getXX() to query LocalDate on its year, month, and date
values.
LocalDate date = LocalDate.parse("2020-08-30");
System.out.println(date.getDayOfMonth());
System.out.println(date.getDayOfWeek());
System.out.println(date.getMonthValue());
System.out.println(date.getYear());
Output: The output of the preceding code looks like this:
30,SUNDAY, 8, 2020
You can use the instance methods isAfter() or isBefore() to determine whether a date is
chronologically before or after another date:

LocalDate
MANIPULATING LOCALDATE
The LocalDate class defines methods with the names minusXX(), plusXX(), and withXX() to
manipulate the date values.
LocalDate bday = LocalDate.of(2052,03,10);
System.out.println(bday.minusWeeks(30));
System.out.println(bday.minusYears(1));
Output of the preceding code: 2051-08-13,2051-03-10
The plusXX():
LocalDate launchCompany = LocalDate.of(2016,02,29);
System.out.println(launchCompany.plusDays(1));
System.out.println(launchCompany.plusMonths(1));
Output of the preceding code: 2016-03-01,2016-03-29

LocalDate
MANIPULATING LOCALDATE
The withXX() methods return a copy of the date instance replacing the specified day,
LocalDate firstSex = LocalDate.of(2036,02,28);
System.out.println(firstSex.withDayOfMonth(1));
System.out.println(firstSex.withYear(1));
Output: of the preceding code looks like this:
2036-02-01,
0001-02-28

LocalTime
To store times like breakfast, conference talk start time, or in-store sale end time, you can use
LocalTime. It stores time in the format hours-minutes-seconds (without a time zone) and to
nanosecond precision. LocalTime is also immutable.
CREATING LOCALTIME
The LocalTime constructor is private, so you must use one of the factory methods to instantiate
it.The static method of() accepts hours, minutes, seconds, and nanoseconds:
LocalTime timeHrsMin = LocalTime.of(12, 12);
LocalTime timeHrsMinSec = LocalTime.of(0, 12,6);
LocalTime timeHrsMinSecNano = LocalTime.of(14, 7, 10,998654578);

LocalTime
CREATING LOCALTIME
• The of() method uses a 24-hour clock to specify the hour value.
• LocalTime doesn’t define a method to pass a.m. or p.m. Use values 0–23 to define hours.
• To get the current time from the system clock, use the static method now():
LocalDate date3 = LocalTime.now();
• You can parse a string to instantiate LocalTime by using its static method parse().You can
either pass a string in the format 15:08:23 (hours:minutes:seconds)
LocalTime time = LocalTime.parse("15:08:23");

LocalTime
USING LOCALTIME CONSTANTS
You can use constants from the LocalTime class to work with predefined times:
■ LocalTime.MIN—Minimum supported time, that is, 00:00
■ LocalTime.MAX—Maximum supported time, that is, 23:59:59.999999999
■ LocalTime.MIDNIGHT—Time when the day starts, that is, 00:00
■ LocalTime.NOON—Noontime, that is, 12:00
QUERYING LOCALTIME
You can use instance methods like getXX() to query LocalTime on its hour,minutes, seconds, and
nanoseconds.All these methods return an int value:
LocalTime time = LocalTime.of(16, 20,12, 98547);
System.out.println(time.getHour());
System.out.println(time.getNano());
Here’s the output: 16,
98547

LocalTime
QUERYING LOCALTIME
• You can use the instance methods isAfter() and isBefore() to check whether a time is after or
before the specified time.The following code outputs true:
LocalTime shreyaFinishTime = LocalTime.parse("17:09:04");
LocalTime paulFinishTime = LocalTime.parse("17:09:12");
if(shreyaFinishTime.isBefore(paulFinishTime))
System.out.println("Shreya wins");
else
System.out.println("Paul wins");
Output: Shreya wins

LocalTime
MANIPULATING LOCALTIME
You can use the instance methods minusHours(), minusMinutes(),minusSeconds(), and
minusNanos() to create and return a copy of LocalTime instances with the specified period
subtracted.
LocalTime movieStartTime = LocalTime.parse("21:00:00");
int commuteMin = 35;
LocalTime shreyaStartTime = movieStartTime.minusMinutes(commuteMin);
System.out.println("Start by " + shreyaStartTime + " from office");
Here’s the output of the preceding code: Start by 20:25 from office
The following example uses the addSeconds() and isAfter() methods to add seconds to a time
and compares it with another time:
int worldRecord = 10;
LocalTime raceStartTime = LocalTime.of(8, 10,55);

LocalTime
MANIPULATING LOCALTIME
LocalTime raceEndTime = LocalTime.of(8, 11,11);
if (raceStartTime.plusSeconds(worldRecord).isAfter(raceEndTime))
System.out.println("New world record");
else
System.out.println("Try harder");
The output of the preceding code looks like this:
The withHour(), withMinute(),withSecond(), and withNano() methods accept an int value and
return a copy of LocalTime with the specified value altered.
LocalTime startTime = LocalTime.of(5, 7, 9);
if (startTime.getMinute() < 30)
startTime = startTime.withMinute(0); System.out.println(startTime);
Here’s the output: 05:00:09

LocalDateTime
If you want to store both date and time (without the time zone), use the class Local- DateTime.
It stores a value like 2050-06-18T14:20:30:908765 (year-month-dayThours
:minutes:seconds:nanoseconds).
Instead of discussing individual methods of this class, here’s an example that covers the
important methods of this class:
LocalDateTime prizeCeremony = LocalDateTime.parse("2050-06-05T14:00:00");
LocalDateTime dateTimeNow = LocalDateTime.now();
if (prizeCeremony.getMonthValue() == 6)
System.out.println("Can't invite president");
else
System.out.println("President invited");

LocalDateTime
LocalDateTime chiefGuestDeparture = LocalDateTime.parse("2050-06-05T14:30:00");
if (prizeCeremony.plusHours(2).isAfter(chiefGuestDeparture))
System.out.println("Chief Guest will leave before ceremony completes");
LocalDateTime eventMgrArrival = LocalDateTime.of(2050, 6, 5, 14,30, 0);
if (eventMgrArrival.isAfter(prizeCeremony.minusHours(3)))
System.out.println("Manager is supposed to arrive 3 hrs earlier")

DateTimeFormatter
Defined in the package java.time.format, the class DateTimeFormatter can be used to format
and parse date and time objects. Defined in the package java.time.format, the class
DateTimeFormatter can be used to format and parse date and time objects.
 INSTANTIATE OR ACCESS DATETIMEFORMATTER
You can instantiate or access a DateTimeFormatter object in multiple ways:
■ By calling a static ofXXX method, passing it a FormatStyle value
■ By access public static fields of DateTimeFormatter
■ By using the static method ofPattern and passing it a string value
• OfLocalizedDate
• OfLocalizedTime
• ofLocalizedDateTime

DateTimeFormatter
■ By calling a static ofXXX method, passing it a FormatStyle value
DateTimeFormatter formatter1 =
DateTimeFormatter.ofLocalizedDate(FormatStyle.MEDIUM);
DateTimeFormatter formatter2 = DateTimeFormatter.ofLocalizedTime(FormatStyle.FULL);
DateTimeFormatter.ofLocalizedDateTime(FormatStyle.LONG);
DateTimeFormatter.ofLocalizedDateTime(FormatStyle.SHORT,
FormatStyle.SHORT);

DateTimeFormatter
Examples of how FormatStyle affects formatting of a date (say,August 11, 2057) or time (say,
14 hours,30 minutes, and 15 seconds) object
FormatStyle Example
FormatStyle.FULL Saturday,August 11,2057
FormatStyle.LONG August 11,2057
FormatStyle.MEDIUM Aug 11,2057
FormatStyle.SHORT 8/11/57
FormatStyle.MEDIUM 2:30:15 PM
FormatStyle.SHORT 2:30 PM

DateTimeFormatter
■ By access public static fields of DateTimeFormatter
Predefined formatters in the class DateTimeFormatter and an example of how they format
a date (say,August 11, 2057) or time (say, 14 hours 30 minutes, and 15 seconds) object
FormatStyle Example
BASIC_ISO_DATE 20570811
ISO_DATE/ISO_LOCAL_DATE 2057-08-11
ISO_TIME/ISO_LOCAL_TIME 14:30:15.312
ISO_DATE_TIME/ISO_LOCAL_DATE_TIME 2057-08-11T14:30:15.312

DateTimeFormatter
■ By using the static method ofPattern and passing it a string value
DateTimeFormatter formatter6= DateTimeFormatter.ofPattern("yyyy MM dd");
 PARSE DATE OR TIME OBJECTS USING DATETIMEFORMATTER
To format a date or time object, you can use either the instance format method in date/time
objects or the instance format method in the DateTimeFormatter class.
DateTimeFormatter formatter = DateTimeFormatter.ofLocalizedDate(FormatStyle.LONG);
LocalDate date = LocalDate.of(2057,8,11);
System.out.println(formatter.format(date));
Outputs:August 11, 2057

DateTimeFormatter
 PARSE DATE OR TIME OBJECTS USING DATETIMEFORMATTER
Following are examples that use different patterns:
LocalDate date = LocalDate.of(2057,8,11); LocalTime time = LocalTime.of(14,30,15);
DateTimeFormatter d1 = DateTimeFormatter.ofPattern("y");
DateTimeFormatter d2 = DateTimeFormatter.ofPattern("YYYY");
DateTimeFormatter d3 = DateTimeFormatter.ofPattern("Y M D");
DateTimeFormatter t1 = DateTimeFormatter.ofPattern("H h m s");
DateTimeFormatter t2 = DateTimeFormatter.ofPattern("'Time now:'HH mm a");
System.out.println(d1.format(date)); System.out.println(d2.format(date));
System.out.println(d3.format(date)); System.out.println(d4.format(date));
System.out.println(t1.format(time)); System.out.println(t2.format(time));
Here’s the output of the preceding code: 2057, 2057,2057 8 223,7, 14 2 30 15,Time now:14 30
PM

DateTimeFormatter
PARSE DATE ORTIME OBJECTS USING DATETIMEFORMATTER
Let’s work with the method parse of LocalDate, LocalTime, or LocalDateTime to parse a string
value using a DateTimeFormatter, producing a date or time object:
DateTimeFormatter d1 = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDate date = LocalDate.parse("2057-01-29",d1 );

Summary
The Date andTime API in Java 8 simplifies how you work with the date and time
classes.We worked with LocalDate,which is used to store only dates of the
format 2016-08-14.LocalTime stores time in the format 14:09:65:23
(hours:minutes:seconds :nanoseconds).The class LocalDateTime stores both date
and time.The class Date-TimeFormatter is used to format date and time using a
predefined or custom format.

New Java Date/Time API

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