Java

Java 8+ Date Time Exmples

21 May 2019 Saurabh Gupta Leave a comment

Pre-Requisite : Java Date and Time Tutorial

In this below example try to cover all possible cases and operations with date and time with Java 8+ APIs.

import java.time.DateTimeException;
import java.time.Duration;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.LocalTime;
import java.time.Month;
import java.time.Period;
import java.time.ZoneId;
import java.time.ZoneOffset;
import java.time.ZonedDateTime;
import java.time.format.DateTimeFormatter;
import java.time.temporal.ChronoUnit;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAdjusters;
import java.time.zone.ZoneRulesException;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;

public class Java8DateTime {

	public static void main(String[] args) {
		//LocalDate lastDay_2014 = LocalDate.of(2014, 12, 32);
		//LocalTime lastDay_2014 = LocalTime.of(12, 12, 23,-1);
		currentDateTime();
		instantAPI();
		GregorianCalendarAPI();
		TimeZoneAPI();
		dateTimeFormattingAndParsing();
		localDateAPI();
		localDateTimeAPI();
		localTimeAPI();

		System.out.println("*********Set Date and Time Manually***************");
		LocalDateTime dateTimePoint=LocalDateTime.now();
		// Set Date and Time manually
		LocalDate datePoint = LocalDate.of(2012, Month.DECEMBER, 12);
		System.out.println("Local Date :" + datePoint);
		// Days after 1970
		datePoint = LocalDate.ofEpochDay(150);
		System.out.println("Local Date :" + datePoint);
		// set String
		LocalTime timePoint = LocalTime.parse("10:15:30");
		System.out.println("Local Time :" + timePoint);
		// Set hours and minutes
		timePoint = LocalTime.of(13, 18);
		System.out.println("Local Time :" + timePoint);

		// Retrieve values
		System.out.println("*********Get Date and Time Values***************");
		datePoint = dateTimePoint.toLocalDate();
		Month month = dateTimePoint.getMonth();
		int day = dateTimePoint.getDayOfMonth();
		int year = dateTimePoint.getYear();
		int hour = dateTimePoint.getHour();
		int minute = dateTimePoint.getMinute();
		int second = dateTimePoint.getSecond();
		System.out.println("Local Date :" + datePoint);
		System.out.printf("Local Date time Format : %d/%d/%d %d:%d:%d", day, month.getValue(), year, hour, minute,
				second);
		System.out.println();
		System.out.println("*********Operation On LocalDate***************");
		// Operation on Local Date
		// Period of 1 year 3 month 2 days
		Period period = Period.of(1, 3, 2);
		LocalDate startDatePoint = datePoint.minus(period);
		System.out.println("Local Date :" + startDatePoint);
		LocalDate endDatePoint = datePoint.plus(period);
		System.out.println("Local Date :" + endDatePoint);

		System.out.println("*********Diffrence of On LocalDate***************");
		// Difference of Date
		Period daysPeriod = Period.between(startDatePoint, endDatePoint);
		System.out.println("Days :" + daysPeriod.getDays());
		System.out.println("Months :" + daysPeriod.getMonths());
		System.out.println("Years :" + daysPeriod.getYears());
		// Another Way
		long days = ChronoUnit.DAYS.between(startDatePoint, endDatePoint);
		long months = ChronoUnit.MONTHS.between(startDatePoint, endDatePoint);
		long years = ChronoUnit.YEARS.between(startDatePoint, endDatePoint);
		System.out.println("Days :" + days);
		System.out.println("Months :" + months);
		System.out.println("Years :" + years);

		// Duration

		// A duration of 3 seconds and 5 nanoseconds
		Duration duration = Duration.ofSeconds(3, 5);
		// Duration oneDay = Duration.between(Temporal., yesterday);

	}

	private static void currentDateTime() {
		System.out.println("*********Current Date and Time***************");

		// Current Date and Time
		LocalDateTime dateTimePoint = LocalDateTime.now();
		System.out.println("Local Date Time :" + dateTimePoint);
		// Current Date
		LocalDate datePoint = LocalDate.now();
		System.out.println("Local Date :" + datePoint);
		// Current Time
		LocalTime timePoint = LocalTime.now();
		System.out.println("Local Time :" + timePoint);

		// Get Instant from java.util.Date
		Instant timestamp = new Date().toInstant();
		System.out.println("Current Timestamp = " + timestamp);

		// java.util.Calendar to Instant
		Instant time = Calendar.getInstance().toInstant();
		System.out.println(time);
	}

	private static void instantAPI() {
		System.out.println("*****************Instant API*******************");
		// Date to Instant
		Instant timestamp = new Date().toInstant();
		System.out.println("Current Timestamp = " + timestamp);
		// Now we can convert Instant to LocalDateTime or other similar classes
		LocalDateTime date = LocalDateTime.ofInstant(timestamp, ZoneId.of(ZoneId.SHORT_IDS.get("PST")));
		System.out.println("Date = " + date);

		// Calendar to Instant
		Instant time = Calendar.getInstance().toInstant();
		System.out.println(time);

		// Date API to Legacy classes
		Date dt = Date.from(Instant.now());
		System.out.println(dt);

		// Instant from timestamp
		Instant specificTime = Instant.ofEpochMilli(timestamp.toEpochMilli());
		System.out.println("Specific Time = " + specificTime);

		// Duration example
		Duration thirtyDay = Duration.ofDays(30);
		System.out.println(thirtyDay);
	}

	private static void localDateAPI() {
		System.out.println("*****************Local Date API*******************");
		LocalDate today = LocalDate.now();

		System.out.println("Current Date=" + today);

		// Creating LocalDate by providing input parameters.
		// Here are chnaces of getting DateTimeException if pass as Invalidate
		// Date format
		LocalDate firstDay_2016 = LocalDate.of(2016, Month.JANUARY, 1);
		System.out.println("Specific Date=" + firstDay_2016);

		try {
			// Here with throw DateTimeException if pass as Invalidate Date
			// format
			LocalDate lastDay_2014 = LocalDate.of(2014, Month.FEBRUARY, 29);
			System.out.println("Specific Date=" + lastDay_2014);
		} catch (DateTimeException ex) {
			ex.printStackTrace();
		}

		// Current date in "Asia/Kolkata", you can get it from ZoneId
		LocalDate todayKolkata = LocalDate.now(ZoneId.of("Asia/Kolkata"));
		System.out.println("Current Date in CST=" + todayKolkata);

		try
		{
		// Will throw java.time.zone.ZoneRulesException: Unknown time-zone ID: IST
		LocalDate todayIST = LocalDate.now(ZoneId.of("IST"));
		}
		catch(ZoneRulesException ex)
		{
			ex.printStackTrace();
		}

		// Getting date from the base date i.e 01/01/1970
		LocalDate dateFromBase = LocalDate.ofEpochDay(365);
		System.out.println("365th day from base date= " + dateFromBase);

        //Get 100 th day of year
		LocalDate hundredDay2014 = LocalDate.ofYearDay(2016, 100);
		System.out.println("100th day of 2014=" + hundredDay2014);

		//Other APIs and Operation on LocalDate

		// Get the Year, check if it's leap year
		System.out.println("Year " + today.getYear() + " is Leap Year? " + today.isLeapYear());

		// Compare two LocalDate for before and after
		System.out.println("Today is before 01/01/2017? " + today.isBefore(LocalDate.of(2017, 1, 1)));

		// Get LocalDateTime from LocalDate
		System.out.println("Current Time=" + today.atTime(LocalTime.now()));

		// plus and minus operations
		System.out.println("20 days after today will be " + today.plusDays(20));
		System.out.println("5 weeks after today will be " + today.plusWeeks(5));
		System.out.println("30 months after today will be " + today.plusMonths(30));

		System.out.println("20 days before today will be " + today.minusDays(20));
		System.out.println("5 weeks before today will be " + today.minusWeeks(5));
		System.out.println("30 months before today will be " + today.minusMonths(30));

		// TemporalAdjusters for adjusting the dates
		LocalDate firstDayOfMonth=today.with(TemporalAdjusters.firstDayOfMonth());
		System.out.println("First date of this month= " + firstDayOfMonth);

		LocalDate lastDayOfYear = today.with(TemporalAdjusters.lastDayOfYear());
		System.out.println("Last date of this year= " + lastDayOfYear);

		Period period = today.until(lastDayOfYear);
		System.out.println("Period Format= " + period);
		System.out.println("Months remaining in the year= " + period.getMonths());

	}

	private static void localTimeAPI() {
		System.out.println("*****************Local Time API*******************");
		// Current Time
		LocalTime time = LocalTime.now();
		System.out.println("Current Time=" + time);

		// Creating LocalTime by providing input arguments
		LocalTime specificTime = LocalTime.of(12, 20, 25, 40);
		System.out.println("Specific Time of Day=" + specificTime);

		// Try creating time by providing invalid inputs
		// LocalTime invalidTime = LocalTime.of(25,20);
		// Exception in thread "main" java.time.DateTimeException:
		// Invalid value for HourOfDay (valid values 0 - 23): 25

		// Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
		LocalTime timeKolkata = LocalTime.now(ZoneId.of("Asia/Kolkata"));
		System.out.println("Current Time in IST=" + timeKolkata);

		// java.time.zone.ZoneRulesException: Unknown time-zone ID: IST
		// LocalTime todayIST = LocalTime.now(ZoneId.of("IST"));

		// Getting date from the base date i.e 01/01/1970
		LocalTime specificSecondTime = LocalTime.ofSecondOfDay(10000);
		System.out.println("10000th second time= " + specificSecondTime);

	}

	private static void localDateTimeAPI() {
		System.out.println("*****************Local Date Time API*******************");
		// Current Date
		LocalDateTime today = LocalDateTime.now();
		System.out.println("Current DateTime=" + today);

		// Current Date using LocalDate and LocalTime
		today = LocalDateTime.of(LocalDate.now(), LocalTime.now());
		System.out.println("Current DateTime=" + today);

		// Creating LocalDateTime by providing input arguments
		LocalDateTime specificDate = LocalDateTime.of(2014, Month.JANUARY, 1, 10, 10, 30);
		System.out.println("Specific Date=" + specificDate);

		// Try creating date by providing invalid inputs
		// LocalDateTime feb29_2014 = LocalDateTime.of(2014, Month.FEBRUARY, 28,
		// 25,1,1);
		// Exception in thread "main" java.time.DateTimeException:
		// Invalid value for HourOfDay (valid values 0 - 23): 25

		// Current date in "Asia/Kolkata", you can get it from ZoneId javadoc
		LocalDateTime todayKolkata = LocalDateTime.now(ZoneId.of("Asia/Kolkata"));
		System.out.println("Current Date in IST=" + todayKolkata);

		// java.time.zone.ZoneRulesException: Unknown time-zone ID: IST
		// LocalDateTime todayIST = LocalDateTime.now(ZoneId.of("IST"));

		// Getting date from the base date i.e 01/01/1970
		LocalDateTime dateFromBase = LocalDateTime.ofEpochSecond(10000, 0, ZoneOffset.UTC);
		System.out.println("10000th second time from 01/01/1970= " + dateFromBase);

	}

	private static void dateTimeFormattingAndParsing() {
		System.out.println("*****************Local DateTime Formatting API*******************");
		// Format examples
		LocalDate date = LocalDate.now();
		// default format
		System.out.println("Default format of LocalDate=" + date);
		// specific format
		System.out.println(date.format(DateTimeFormatter.ofPattern("d::MMM::uuuu")));
		System.out.println(date.format(DateTimeFormatter.BASIC_ISO_DATE));

		LocalDateTime dateTime = LocalDateTime.now();
		// default format
		System.out.println("Default format of LocalDateTime=" + dateTime);
		// specific format
		System.out.println(dateTime.format(DateTimeFormatter.ofPattern("d::MMM::uuuu HH::mm::ss")));
		System.out.println(dateTime.format(DateTimeFormatter.BASIC_ISO_DATE));

		Instant timestamp = Instant.now();
		// default format
		System.out.println("Default format of Instant=" + timestamp);

		// Parse examples
		LocalDateTime dt = LocalDateTime.parse("27::Apr::2014 21::39::48",
				DateTimeFormatter.ofPattern("d::MMM::uuuu HH::mm::ss"));
		System.out.println("Default format after parsing = " + dt);

	}

	private static void GregorianCalendarAPI() {
		System.out.println("*****************Gregorian Calendar API*******************");
		// ZonedDateTime from specific Calendar
		ZonedDateTime gregorianCalendarDateTime = new GregorianCalendar().toZonedDateTime();
		System.out.println(gregorianCalendarDateTime);

		GregorianCalendar gc = GregorianCalendar.from(gregorianCalendarDateTime);
		System.out.println(gc);
	}

	private static void TimeZoneAPI() {
		System.out.println("*****************Time Zone API*******************");
		// TimeZone to ZoneId
		ZoneId defaultZone = TimeZone.getDefault().toZoneId();
		System.out.println(defaultZone);

		TimeZone tz = TimeZone.getTimeZone(defaultZone);
		System.out.println(tz);

	}

}

Output


*********Current Date and Time***************
Local Date Time :2019-05-16T11:50:59.302
Local Date :2019-05-16
Local Time :11:50:59.303
Current Timestamp = 2019-05-16T06:20:59.303Z
2019-05-16T06:20:59.358Z
*****************Instant API*******************
Current Timestamp = 2019-05-16T06:20:59.369Z
Date = 2019-05-15T23:20:59.369
2019-05-16T06:20:59.373Z
Thu May 16 11:50:59 IST 2019
Specific Time = 2019-05-16T06:20:59.369Z
PT720H
*****************Gregorian Calendar API*******************
2019-05-16T11:50:59.387+05:30[Asia/Calcutta]
java.util.GregorianCalendar[time=1557987659387,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Calcutta",offset=19800000,dstSavings=0,useDaylight=false,transitions=7,lastRule=null],firstDayOfWeek=2,minimalDaysInFirstWeek=4,ERA=1,YEAR=2019,MONTH=4,WEEK_OF_YEAR=20,WEEK_OF_MONTH=3,DAY_OF_MONTH=16,DAY_OF_YEAR=136,DAY_OF_WEEK=5,DAY_OF_WEEK_IN_MONTH=3,AM_PM=0,HOUR=11,HOUR_OF_DAY=11,MINUTE=50,SECOND=59,MILLISECOND=387,ZONE_OFFSET=19800000,DST_OFFSET=0]
*****************Time Zone API*******************
Asia/Calcutta
sun.util.calendar.ZoneInfo[id="Asia/Calcutta",offset=19800000,dstSavings=0,useDaylight=false,transitions=7,lastRule=null]
*****************Local DateTime Formatting API*******************
Default format of LocalDate=2019-05-16
16::May::2019
20190516
Default format of LocalDateTime=2019-05-16T11:50:59.551
16::May::2019 11::50::59
20190516
Default format of Instant=2019-05-16T06:20:59.551Z
Default format after parsing = 2014-04-27T21:39:48
*****************Local Date API*******************
Current Date=2019-05-16
Specific Date=2016-01-01
java.time.DateTimeException: Invalid date 'February 29' as '2014' is not a leap year
Current Date in CST=2019-05-16
365th day from base date= 1971-01-01
    at java.time.LocalDate.create(Unknown Source)
    at java.time.LocalDate.of(Unknown Source)
    at datetime.Java8DateTime.localDateAPI(Java8DateTime.java:160)
    at datetime.Java8DateTime.main(Java8DateTime.java:34)
java.time.zone.ZoneRulesException: Unknown time-zone ID: IST
    at java.time.zone.ZoneRulesProvider.getProvider(Unknown Source)
    at java.time.zone.ZoneRulesProvider.getRules(Unknown Source)
    at java.time.ZoneRegion.ofId(Unknown Source)
    at java.time.ZoneId.of(Unknown Source)
    at java.time.ZoneId.of(Unknown Source)
    at datetime.Java8DateTime.localDateAPI(Java8DateTime.java:173)
    at datetime.Java8DateTime.main(Java8DateTime.java:34)
100th day of 2014=2016-04-09
Year 2019 is Leap Year? false
Today is before 01/01/2017? false
Current Time=2019-05-16T11:50:59.619
20 days after today will be 2019-06-05
5 weeks after today will be 2019-06-20
30 months after today will be 2021-11-16
20 days before today will be 2019-04-26
5 weeks before today will be 2019-04-11
30 months before today will be 2016-11-16
First date of this month= 2019-05-01
Last date of this year= 2019-12-31
Period Format= P7M15D
Months remaining in the year= 7
*****************Local Date Time API*******************
Current DateTime=2019-05-16T11:50:59.620
Current DateTime=2019-05-16T11:50:59.620
Specific Date=2014-01-01T10:10:30
Current Date in IST=2019-05-16T11:50:59.620
10000th second time from 01/01/1970= 1970-01-01T02:46:40
*****************Local Time API*******************
Current Time=11:50:59.620
Specific Time of Day=12:20:25.000000040
Current Time in IST=11:50:59.620
10000th second time= 02:46:40
*********Set Date and Time Manually***************
Local Date :2012-12-12
Local Date :1970-05-31
Local Time :10:15:30
Local Time :13:18
*********Get Date and Time Values***************
Local Date :2019-05-16
Local Date time Format : 16/5/2019 11:50:59
*********Operation On LocalDate***************
Local Date :2018-02-14
Local Date :2020-08-18
*********Difference of On LocalDate***************
Days :4
Months :6
Years :2
Days :916
Months :30
Years :2

Above solutions are my search to perform all type of operations with date and time with java 8 API generally face while development. If you face other issue apart from it. Please mention in comments that will help with others.

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