The document provides an overview of the Java Date Time API. It introduces the LocalDate, LocalTime, and LocalDateTime classes, which represent dates, times, and date-times without time zone information. The summary describes the key features and methods of each class, including how to get and set date/time fields, perform date/time arithmetic, and format and parse dates and times. It also shows how to work with dates and times across time zones using ZonedDateTime.

1. Programming in Java
Topic: Date Time API

2. Contents…
 Introduction
 Local Date
 Local Time
 Local Date Time

3. Introduction
 New DateTime API is introduced in jdk8.
 LocalDate, LocalTime and LocalDateTime classes are provided
in java.time package.
 The Date class encapsulates the current date and time.

4. Java Date and Time API goals
 Classes and methods should be straight forward.
 The API should support fluent API approach.
 Instances of Date and Time objects should be immutable.
 Should be thread safe.
 Use ISO standard to define Date and Time.
 API should support strong type checks.
 Allows developers to extend API.

5. Working with Local Date and Time
 Java.time package provides two classes for working with local
Date and Time.
 LocalDate
 Does not include time
 A year-month-day representation
 toString – ISO 8601 format(YYYY-MM-DD)
 LocalTime
 Does not include date
 Stores hours:minutes:seconds:nanoseconds
 toString- (HH:mm:ss.SSS)

6. LocalDate Class

7. LocalDate Class
 A date without a time-zone in the ISO-8601 calendar system,
such as 2021-02-03(YYYY-MM-DD).
 LocalDate is an immutable date-time object that represents a
date, often viewed as year-month-day.
 Other date fields, such as day-of-year, day-of-week and week-
of-year, can also be accessed.
 This class does not store or represent a time or time-zone so its
portable across time zones.

8. Methods of LocalDate
 public static LocalDate now()
 public static LocalDate now(ZoneId zone)
 public static LocalDate of(int year, Month month, int
dayOfMonth)
 public static LocalDate of(int year, int month, int dayOfMonth)
Note: DateTimeException can be thrown.
 public static LocalDate parse(CharSequence text)
Note: DateTimeParseException can be thrown.

9. Example
LocalDate ldt = LocalDate.now();
ldt = LocalDate.of(2015, Month.FEBRUARY, 28);
ldt = LocalDate.of(2015, 2, 13);
ldt = LocalDate.parse("2017-02-28”);

10. Methods of LocalDate
Methods
 public int getYear()
 public int getMonthValue()
 public Month getMonth()
 public int getDayOfMonth()
 public int getDayOfYear()
 public DayOfWeek getDayOfWeek()
 public boolean isLeapYear()

11. Methods of LocalDate
 public LocalDate withYear(int year)
 public LocalDate withMonth(int month)
 public LocalDate withDayOfMonth(int dayOfMonth)
 public LocalDate withDayOfYear(int dayOfYear)

12. Methods of LocalDate
 public LocalDate plusYears(long yearsToAdd)
 public LocalDate plusMonths(long monthsToAdd)
 public LocalDate plusWeeks(long weeksToAdd)
 public LocalDate plusDays(long daysToAdd)
 public LocalDate minusYears(long yearsToSubtract)
 public LocalDate minusMonths(long monthsToSubtract)
 public LocalDate minusWeeks(long weeksToSubtract)
 public LocalDate minusDays(long daysToSubtract)

13. import java.time.LocalDate;
public class LocalDateExample {
public static void main(String[] args){
LocalDate date=LocalDate.now();
LocalDate yesterday=date.minusDays(1);
LocalDate tomorrow=yesterday.plusDays(2);
System.out.println("Today date: "+date);
System.out.println("Yesterday date:"+yesterday);
System.out.println("Tommorow date: "+tomorrow);
}
}

14. import java.time.LocalDate;
import java.time.Month;
public class LocalDateExample {
public static void main(String[] args) {
LocalDate now = LocalDate.now();
System.out.println("Present date : " +now);
int year = now.getYear();
Month month = now.getMonth();
int day = now.getDayOfMonth();
System.out.println("year : " + year + " , month : " + month + ",
day : " + day);
int monthInt = now.getMonthValue();
System.out.println("today date : " + year + "-" + monthInt +
"-" + day);
LocalDate oldDate = LocalDate.of(2015, 2,2);
System.out.println("Old date : " + oldDate);
}
}

15. LocalTime Class

16. LocalTime Class
 A time without a time-zone in the ISO-8601 calendar system,
such as 10:15:30. 13
 LocalTime is an immutable date-time object that represents a
time, often viewed as hour-minute-second.
 Time is represented to nanosecond precision.
 For example, the value "13:45:30.123" can be stored in a
LocalTime.
 This class does not store or represent a date or time-zone.

17. Methods of LocalTime
Methods
 public static LocalTime now()
 public static LocalTime now(ZoneId zone)
 public static LocalTime of(int hour, int minute)
 public static LocalTime of(int hour, int minute, int second)
 public static LocalTime of(int hour, int min, int sec, int nsec)
 public static LocalTime parse(CharSequence text)

18. Methods of LocalTime
Methods
 public int getHour()
 public int getMinute()
 public int getSecond()
 public int getNano()
 public boolean isAfter(LocalTime l)
 public boolean isBefore(LocalTime l)
 public LocalDateTime atDate(LocalDate d)

19. Methods of LocalTime
Methods
 public LocalTime withHour(int hour)
 public LocalTime withMinute(int min)
 public LocalTime withSecond(int sec)
 public LocalTime withNano(int ns)

20. Methods of LocalTime
Methods
 public LocalTime plusHours(long hours)
 public LocalTime plusMinutes(long min)
 public LocalTime plusSeconds(long sec)
 public LocalTime plusNanos(long ns)
 public LocalTime minusHours(long hours)
 public LocalTime minusMinutes(long min)
 public LocalTime minusSeconds(long sec)
 public LocalTime minusNanos(long ns)

21. import java.time.LocalTime;
public class LocalTimeExample {
public static void main(String[] args) {
LocalTime now = LocalTime.now();
System.out.println("Present time : " +now);
int hour = now.getHour();
int minute = now.getMinute();
int second = now.getSecond();
System.out.println("Hour : " + hour + " ,Minute : " + minute + ",
Second : " + second);
int nanoSec = now.getNano();
System.out.println("time now in format : " + hour + ":" + minute
+ ":0" + second + ":" + nanoSec);
LocalTime oldTime = LocalTime.of(13, 20,25);
System.out.println("Old time : " + oldTime);
}
}

22. LocalDateTime Class

23. LocalDateTime Class
 A date-time without a time-zone in the ISO-8601 calendar
system, such as 2007-12-03T10:15:30.
 LocalDateTime is an immutable date-time object that
represents a date-time, often viewed as year-month-day-hour-
minute-second.
 Other date and time fields, such as day-of-year, day-of-week
and week-of-year, can also be accessed.
 Time is represented to nanosecond precision.
 For example, the value "2nd October 2007 at
13:45.30.123456789" can be stored in a LocalDateTime.

24. Methods of LocalDateTime
Methods
 public static LocalDateTime now()
 public static LocalDateTime now(ZoneId zone)
 public static LocalDateTime of(int year, int mnth, int day, int
hour, int mint)
 public static LocalDateTime of(int year, int mnth, int day, int
hour, int mint, int sec)
 public static LocalDateTime of(int year, int mnth, int day, int
hour, int mint, int sec, int nsec)
 public static LocalDateTime of(LocalDate d, LocalTime t)
 public static LocalDateTime parse(CharSequence text)

25. import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Month;
class LocalDateTimeExample {
public static void main(String[] args) {
LocalDateTime now = LocalDateTime.now();
System.out.println("Present date : " +now);
int year = now.getYear();
Month month = now.getMonth();
int day = now.getDayOfMonth();
int hour = now.getHour();
int minute = now.getMinute();
int second = now.getSecond();
System.out.println("year : " + year + " ,month : " + month + ", day : " + day + "Hour :
" + hour+ " , Minute : " + minute + ", Second :" + second);
LocalDateTime oldDate = LocalDateTime.of(2000, 12, 10, 10, 10, 10);
System.out.println("Old date : " + oldDate);
LocalDate newlocalDate = now.toLocalDate();
System.out.println("newlocalDate:" +newlocalDate);
LocalTime newlocalTime = now.toLocalTime();
System.out.println("newlocalTime:"+ newlocalTime);
LocalDateTime strToDate =LocalDateTime.parse("2020-11-10T10:10:10");
System.out.println("String to Date : " +strToDate);
} }

26. Working with dates and
times across time zones

27. Date/Time Formatting
 java.time.format.DateTimeFormatter class is used for
printing and parsing date-time objects.
 This class works by using:
Predefined constants, such as ISO_LOCAL_DATE
Pattern letters, such as yyyy-MMM-dd
Localized styles, such as long or medium

28. Date/Time Formatting
 The date-time classes provide two methods - one for
formatting and one for Parsing.
Formatting Example:
LocalDateTime dt =
LocalDateTime.of( 2010, Month.JULY, 03, 09, 0, 30 );
String isoDateTime =
dt.format(DateTimeFormatter.ISO_DATE_TIME);
Parsing Example:
LocalDate dt = LocalDate.parse("2014/09/19 14:05:12",
DateTimeFormatter.ofPattern( "yyyy/MM/dd kk:mm:ss" ) );

29. import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
class ZonedDateTimeExample {
public static void main(String[] args) {
LocalDateTime currentDateTime = LocalDateTime.now();
System.out.println("India current DateTime : " + currentDateTime);
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd MMM yyyy
HH:mm:ss");
ZonedDateTime zonedDateTime =
currentDateTime.atZone(ZoneId.of("Australia/Sydney"));
System.out.println("Aus Zoned time : " + formatter.format(zonedDateTime));
ZoneId zoneId = zonedDateTime.getZone();
System.out.println("zone id : " + zoneId);
ZonedDateTime pstZoneTime = zonedDateTime.withZoneSameInstant(ZoneId.of
("America/Los_Angeles"));
System.out.println("PST time now : " + formatter.format(pstZoneTime));
}
}

31. ABSTRACT CLASS
vs
INTERFACE

32. METHOD
vs
CONSTRUCTOR

33. ENUM
vs
CLASS

34. METHOD OVERLOADING
vs
METHOD OVERRIDDING
IN JAVA

35. STATIC BLOCK
vs
ANONYMOUS BLOCK

36. STATIC VARIABLE
vs
LOCAL VARIABLE
Vs
INSTANCE VARIABLE