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package java8;
import java.sql.Timestamp;
import java.text.DateFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.time.Duration;
import java.time.Instant;
import java.time.LocalDate;
import java.time.LocalDateTime;
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.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.concurrent.TimeUnit;
/**
*
* @author NAYANK
*
*In old days, we use the following classic Date and Calendar APIs to represent and manipulate date.
java.util.Date – date and time, print with default time-zone.
java.util.Calendar – date and time, more methods to manipulate date.
java.text.SimpleDateFormat – formatting (date -> text), parsing (text -> date) for date and calendar.
In Java 8, a new series of date and time APIs (JSR310 and inspired by Joda-time) are created in the new java.time package.
java.time.LocalDate – date without time, no time-zone.
java.time.LocalTime – time without date, no time-zone.
java.time.LocalDateTime – date and time, no time-zone.
java.time.ZonedDateTime – date and time, with time-zone.
java.time.DateTimeFormatter – formatting (date -> text), parsing (text -> date) for java.time
java.time.Instant – date and time for machine, seconds passed since the Unix epoch time (midnight of January 1, 1970 UTC)
java.time.Duration – Measures time in seconds and nanoseconds.
java.time.Period – Measures time in years, months and days.
java.time.TemporalAdjuster – Adjust date.
*/
public class Java8DateTimeExample {
public static void main(String[] args) throws ParseException, InterruptedException {
//Convert Date to String.
SimpleDateFormat sdf = new SimpleDateFormat("dd/M/yyyy");
String date = sdf.format(new Date());
System.out.println(date); //15/10/2013
//Convert String to Date.
SimpleDateFormat sdf1 = new SimpleDateFormat("dd-M-yyyy hh:mm:ss");
String dateInString = "31-08-1982 10:20:56";
Date date1 = sdf1.parse(dateInString);
System.out.println(date1); //Tue Aug 31 10:20:56 SGT 1982
//Get current date time
SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Date date2 = new Date();
System.out.println(dateFormat.format(date2)); //2013/10/15 16:16:39
// Convert Calendar to Date
Calendar calendar = Calendar.getInstance();
Date date3 = calendar.getTime();
System.out.println(dateFormat.format(date3));
//2. Java Calendar Examples
//Get current date time
SimpleDateFormat sdf2 = new SimpleDateFormat("yyyy MMM dd HH:mm:ss");
Calendar calendar1 = new GregorianCalendar(2013,0,31);
System.out.println(sdf2.format(calendar1.getTime()));
// Simple Calendar example
SimpleDateFormat sdf4 = new SimpleDateFormat("yyyy MMM dd HH:mm:ss");
Calendar calendar2 = new GregorianCalendar(2013,1,28,13,24,56);
int year = calendar2.get(Calendar.YEAR);
int month = calendar2.get(Calendar.MONTH); // Jan = 0, dec = 11
int dayOfMonth = calendar2.get(Calendar.DAY_OF_MONTH);
int dayOfWeek = calendar2.get(Calendar.DAY_OF_WEEK);
int weekOfYear = calendar2.get(Calendar.WEEK_OF_YEAR);
int weekOfMonth= calendar2.get(Calendar.WEEK_OF_MONTH);
int hour = calendar2.get(Calendar.HOUR); // 12 hour clock
int hourOfDay = calendar2.get(Calendar.HOUR_OF_DAY); // 24 hour clock
int minute = calendar2.get(Calendar.MINUTE);
int second = calendar2.get(Calendar.SECOND);
int millisecond= calendar2.get(Calendar.MILLISECOND);
System.out.println(sdf4.format(calendar.getTime()));
System.out.println("year \t\t: " + year);
System.out.println("month \t\t: " + month);
System.out.println("dayOfMonth \t: " + dayOfMonth);
System.out.println("dayOfWeek \t: " + dayOfWeek);
System.out.println("weekOfYear \t: " + weekOfYear);
System.out.println("weekOfMonth \t: " + weekOfMonth);
System.out.println("hour \t\t: " + hour);
System.out.println("hourOfDay \t: " + hourOfDay);
System.out.println("minute \t\t: " + minute);
System.out.println("second \t\t: " + second);
System.out.println("millisecond \t: " + millisecond);
System.out.println("#1. " + sdf4.format(calendar2.getTime()));
//update a date
calendar2.set(Calendar.YEAR, 2014);
calendar2.set(Calendar.MONTH, 11);
calendar2.set(Calendar.MINUTE, 33);
System.out.println("#2. " + sdf4.format(calendar2.getTime()));
//Convert Date to Calendar.
SimpleDateFormat sdf5 = new SimpleDateFormat("dd-M-yyyy hh:mm:ss");
String dateInString1 = "22-01-2015 10:20:56";
Date date5 = sdf5.parse(dateInString);
Calendar calendar5 = Calendar.getInstance();
calendar.setTime(date5);
compareDates();
getCurrentDate();
convertStringToDate();
calculateElapsedTime();
convertStringToLocalDate();
formatLocalDate();
instantExample();
convertDateToLocalDate();
durationAndPeriod();
addDaysToDate();
}
private static void addDaysToDate() {
Date currentDate = new Date();
System.out.println(new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(currentDate));
Calendar c = Calendar.getInstance();
c.setTime(currentDate);
c.add(Calendar.YEAR, 1);
c.add(Calendar.MONTH, 1);
c.add(Calendar.DATE, 1); //same with c.add(Calendar.DAY_OF_MONTH, 1);
c.add(Calendar.HOUR, 1);
c.add(Calendar.MINUTE, 1);
c.add(Calendar.SECOND, 1);
Date currentDatePlusOne = c.getTime();
System.out.println(new SimpleDateFormat("yyyy/MM/dd HH:mm:ss").format(currentDatePlusOne));
}
private static void durationAndPeriod() {
Duration oneHours = Duration.ofHours(1);
System.out.println(oneHours.getSeconds() + " seconds");
Duration oneHours2 = Duration.of(1, ChronoUnit.HOURS);
System.out.println(oneHours2.getSeconds() + " seconds");
// Test Duration.between
System.out.println("\n--- Duration.between --- ");
LocalDateTime oldDate = LocalDateTime.of(2016, Month.AUGUST, 31, 10, 20, 55);
LocalDateTime newDate = LocalDateTime.of(2016, Month.NOVEMBER, 9, 10, 21, 56);
System.out.println(oldDate);
System.out.println(newDate);
//count seconds between dates
Duration duration = Duration.between(oldDate, newDate);
System.out.println(duration.getSeconds() + " seconds");
Period tenDays = Period.ofDays(10);
System.out.println(tenDays.getDays()); //10
Period oneYearTwoMonthsThreeDays = Period.of(1, 2, 3);
System.out.println(oneYearTwoMonthsThreeDays.getYears()); //1
System.out.println(oneYearTwoMonthsThreeDays.getMonths()); //2
System.out.println(oneYearTwoMonthsThreeDays.getDays()); //3
System.out.println("\n--- Period.between --- ");
LocalDate oldDate1 = LocalDate.of(1982, Month.AUGUST, 31);
LocalDate newDate1 = LocalDate.of(2016, Month.NOVEMBER, 9);
System.out.println(oldDate1);
System.out.println(newDate1);
// check period between dates
Period period = Period.between(oldDate1, newDate1);
System.out.print(period.getYears() + " years,");
System.out.print(period.getMonths() + " months,");
System.out.print(period.getDays() + " days");
long years = ChronoUnit.YEARS.between(oldDate1, newDate1);
System.out.println(years + " years");
}
private static void convertDateToLocalDate() {
/*
* Date -> Instant + System default time zone = LocalDate
Date -> Instant + System default time zone = LocalDateTime
Date -> Instant + System default time zone = ZonedDateTime
*/
//Asia/Kuala_Lumpur +8
ZoneId defaultZoneId = ZoneId.systemDefault();
System.out.println("System Default TimeZone : " + defaultZoneId);
//toString() append +8 automatically.
Date date = new Date();
System.out.println("date : " + date);
//1. Convert Date -> Instant
Instant instant = date.toInstant();
System.out.println("instant : " + instant); //Zone : UTC+0
//2. Instant + system default time zone + toLocalDate() = LocalDate
LocalDate localDate = instant.atZone(defaultZoneId).toLocalDate();
System.out.println("localDate : " + localDate);
//3. Instant + system default time zone + toLocalDateTime() = LocalDateTime
LocalDateTime localDateTime = instant.atZone(defaultZoneId).toLocalDateTime();
System.out.println("localDateTime : " + localDateTime);
//4. Instant + system default time zone = ZonedDateTime
ZonedDateTime zonedDateTime = instant.atZone(defaultZoneId);
System.out.println("zonedDateTime : " + zonedDateTime);
}
private static void instantExample() {
Instant instant = Instant.now();
System.out.println("Instant : " + instant);
LocalDateTime ldt = LocalDateTime.ofInstant(instant, ZoneOffset.UTC);
System.out.println("LocalDateTime : " + ldt);
ZonedDateTime jpTime = instant.atZone(ZoneId.of("Asia/Tokyo"));
System.out.println("ZonedDateTime : " + jpTime);
System.out.println("OffSet : " + jpTime.getOffset());
}
private static void formatLocalDate() {
LocalDateTime now = LocalDateTime.now();
System.out.println("Before : " + now);
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
String formatDateTime = now.format(formatter);
System.out.println("After : " + formatDateTime);
}
private static void convertStringToLocalDate() {
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("d/MM/yyyy");
String date = "16/08/2016";
LocalDate localDate = LocalDate.parse(date, formatter);
System.out.println("localDate:"+localDate);
}
private static void calculateElapsedTime() throws InterruptedException {
long lStartTime = System.nanoTime();
int i=0;
Thread.sleep(100);
long lEndTime = System.nanoTime();
long output = lEndTime - lStartTime;
System.out.println("Elapsed time in milliseconds: " + output / 1000000);
long lStartTime1 = System.currentTimeMillis();
TimeUnit.SECONDS.sleep(1);
long lEndTime1 = System.currentTimeMillis();
System.out.println("Elapsed time in milliseconds: " + (lEndTime1-lStartTime1) );
System.out.println("epoch instant:"+Instant.now().toEpochMilli());
System.out.println("Date.gettime:"+new Date().getTime());
}
private static void convertStringToDate() throws ParseException {
SimpleDateFormat formatter = new SimpleDateFormat("dd-MMM-yyyy");
String dateInString = "7-Jun-2013";
Date date = formatter.parse(dateInString);
System.out.println(date);
System.out.println(formatter.format(date));
}
private static void getCurrentDate() {
DateFormat sdf = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
DateTimeFormatter dtf = DateTimeFormatter.ofPattern("yyyy/MM/dd HH:mm:ss");
Date date = new Date();
System.out.println(sdf.format(date));
Calendar cal = Calendar.getInstance();
System.out.println(sdf.format(cal.getTime()));
LocalDateTime now = LocalDateTime.now();
System.out.println(dtf.format(now));
LocalDate localDate = LocalDate.now();
System.out.println(DateTimeFormatter.ofPattern("yyy/MM/dd").format(localDate));
Timestamp timestamp = new Timestamp(System.currentTimeMillis());
System.out.println(timestamp);
Date date1 = new Date();
System.out.println(new Timestamp(date1.getTime()));
System.out.println(timestamp.getTime());
System.out.println(sdf.format(timestamp));
//2. java.time.Instant
}
private static void compareDates() throws ParseException {
//1. Date.compareTo()
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
Date date1 = sdf.parse("2009-12-31");
Date date2 = sdf.parse("2010-01-31");
System.out.println("date1 : " + sdf.format(date1));
System.out.println("date2 : " + sdf.format(date2));
if (date1.compareTo(date2) > 0) {
System.out.println("Date1 is after Date2");
} else if (date1.compareTo(date2) < 0) {
System.out.println("Date1 is before Date2");
} else if (date1.compareTo(date2) == 0) {
System.out.println("Date1 is equal to Date2");
} else {
System.out.println("How to get here?");
}
//2. Date.before(), Date.after() and Date.equals()
if (date1.after(date2)) {
System.out.println("Date1 is after Date2");
}
if (date1.before(date2)) {
System.out.println("Date1 is before Date2");
}
if (date1.equals(date2)) {
System.out.println("Date1 is equal Date2");
}
//3. Calender.before(), Calender.after() and Calender.equals()
Calendar cal1 = Calendar.getInstance();
Calendar cal2 = Calendar.getInstance();
cal1.setTime(date1);
cal2.setTime(date2);
if (cal1.after(cal2)) {
System.out.println("Date1 is after Date2");
}
if (cal1.before(cal2)) {
System.out.println("Date1 is before Date2");
}
if (cal1.equals(cal2)) {
System.out.println("Date1 is equal Date2");
}
// 4. Java 8 java.time.LocalDate
DateTimeFormatter sdf1 = DateTimeFormatter.ofPattern("yyyy-MM-dd");
LocalDate date11 = LocalDate.of(2009, 12, 31);
LocalDate date21 = LocalDate.of(2010, 01, 31);
System.out.println("date1 : " + sdf1.format(date11));
System.out.println("date2 : " + sdf1.format(date21));
System.out.println("Is...");
if (date11.isAfter(date21)) {
System.out.println("Date1 is after Date2");
}
if (date11.isBefore(date21)) {
System.out.println("Date1 is before Date2");
}
if (date11.isEqual(date21)) {
System.out.println("Date1 is equal Date2");
}
System.out.println("CompareTo...");
if (date11.compareTo(date21) > 0) {
System.out.println("Date1 is after Date2");
} else if (date11.compareTo(date21) < 0) {
System.out.println("Date1 is before Date2");
} else if (date11.compareTo(date21) == 0) {
System.out.println("Date1 is equal to Date2");
} else {
System.out.println("How to get here?");
}
}
}