LocalDate date = LocalDate.of(2017, 9, 21);
int year = date.getYear();
Month month = date.getMonth();
int day = date.getDayOfMonth();
DayOfWeek dow = date.getDayOfWeek();
LocalDate date2 = LocalDate.parse("2017-09-21");

LocalDate nowDate = LocalDate.now();
System.out.println(nowDate);

//get메서드에 ChronoField Enum을 넘겨도 된다
int y = date.get(ChronoField.YEAR);
int m = date.get(ChronoField.MONTH_OF_YEAR);
int d = date.get(ChronoField.DAY_OF_MONTH);
System.out.println(y+" "+m+" "+d);

//항목마다 정의된 get메서드를 호출해도 된다
int y2 = date.getYear();
int m2 = date.getMonthValue();
int d2 = date.getDayOfMonth();
System.out.println(y2+" "+m2+" "+d2);

int len = date.lengthOfMonth(); //달마다 일 수
boolean leap = date.isLeapYear(); //윤년여부를 알 수 있음
System.out.println(month.getValue()); //달은 1월부터 1, 12월이 12
System.out.println(dow.getValue()); //요일은 월요일부터 1, 일요일이 7

//LocalTime
LocalTime time = LocalTime.of(13, 45, 20);
int hour = time.getHour();
int minute = time.getMinute();
int second = time.getSecond();

//문자열을 파싱해서 만들 수도 있음
LocalTime time2 = LocalTime.parse("13:45:20");

//LocalDateTime은 날짜, 시간 모두를 표현
LocalDateTime dt1 = LocalDateTime.of(2017, Month.SEPTEMBER, 21, 13, 45, 20);
System.out.println(Month.SEPTEMBER);

LocalDateTime dt2 = LocalDateTime.of(date, time);
LocalDateTime dt3 = date.atTime(13, 45, 20);
LocalDateTime dt4 = date.atTime(time);
LocalDateTime dt5 = time.atDate(date);
LocalDate date3 = dt1.toLocalDate();
LocalTime time3 = dt1.toLocalTime();

//Instant
System.out.println(Instant.ofEpochSecond(3));
System.out.println(Instant.ofEpochSecond(3, 0));
System.out.println(Instant.ofEpochSecond(2, 1_000_000_000));
System.out.println(Instant.ofEpochSecond(4, -1_000_000_000));

try{
    int day = Instant.now().get(ChronoField.DAY_OF_MONTH);
}catch(UnsupportedTemporalTypeException e){
    e.printStackTrace();
}

//변환할 때는 시간대정보를 지정해주어야 한다. 시간대정보는 다다음절에서 다룸.
int day = DateTime.ofInstant(Instant.now(), ZoneOffset.UTC).get(ChronoField.DAY_OF_MONTH);

//Duration
LocalTime time1 = LocalTime.now();
LocalTime time2 = time1.plusHours(1);
LocalDate dateTime1 = LocalDate.now();
LocalDate dateTime2 = dateTime1.plusDays(1);
Instant instant1 = Instant.now();
Instant instant2 = instant1.plusMillis(1000);

Duration d1 = Duration.between(time1, time2);
System.out.println("d1: "+d1);
try{ //Duration은 초와 나노초로 시간단위를 표현하므로 LocalDate는 사용할 수 없다.
    Duration d2 = Duration.between(dateTime1, dateTime2);
    System.out.println("d2: "+d2);
}catch(UnsupportedTemporalTypeException e){
    //e.printStackTrace();
}
Duration d3 = Duration.between(instant1, instant2);
System.out.println("d3: "+d3);

LocalDateTime ldt1 = LocalDateTime.now();
LocalDateTime ldt2 = ldt1.plusYears(1);

Duration test = Duration.between(ldt1, ldt2);
System.out.println("duration test: "+test);

//Period test2 = Period.between(ldt1, ldt2); //예외를 던진다
Period test2 = Period.between(ldt1.toLocalDate(), ldt2.toLocalDate());
System.out.println("period test: "+test2);
//period test: P1Y

LocalDateTime ldt1 = LocalDateTime.now();
LocalDateTime ldt2 = ldt1.plusYears(1);

Duration test = Duration.between(ldt1, ldt2);
System.out.println("duration test: "+test);
//duration test: PT8760H

//with으로 값을 지정
LocalDate date1 = LocalDate.of(2017, 9, 21);
LocalDate date2 = date1.withYear(2011);
LocalDate date3 = date2.withDayOfMonth(25);
LocalDate date4 = date3.with(ChronoField.MONTH_OF_YEAR, 2);

//plus, minus로 연산
LocalDate date22 = date1.plusWeeks(1);
LocalDate date33 = date22.minusYears(1);
LocalDate date44 = date33.plus(6, ChronoUnit.MONTHS);

LocalDate date = LocalDate.of(2014, 3, 18);
date = date.with(ChronoField.MONTH_OF_YEAR, 9);
date = date.plusYears(2).minusDays(10);
date.withYear(2011);

LocalDate date1 = LocalDate.now(); //2022-01-21
LocalDate date2 = date1.with(nextOrSame(DayOfWeek.SUNDAY)); //2022-01-23
LocalDate date3 = date2.with(lastDayOfMonth()); //2022-01-31

LocalDate date = LocalDate.now().with(new NextWorkingDay());

import java.time.DayOfWeek;
import java.time.temporal.ChronoField;
import java.time.temporal.ChronoUnit;
import java.time.temporal.Temporal;
import java.time.temporal.TemporalAdjuster;

public class NextWorkingDay implements TemporalAdjuster {
    @Override
    public Temporal adjustInto(Temporal temporal) {
        DayOfWeek dow = DayOfWeek.of(temporal.get(ChronoField.DAY_OF_WEEK));
        int dayToAdd = 1;
        if(dow == DayOfWeek.FRIDAY) dayToAdd = 3;
        else if(dow == DayOfWeek.SATURDAY) dayToAdd = 2;
        return temporal.plus(dayToAdd, ChronoUnit.DAYS);
    }
}

LocalDate date1 = LocalDate.now().with(
  temporal -> {
      DayOfWeek dow = DayOfWeek.of(temporal.get(ChronoField.DAY_OF_WEEK));
      int dayToAdd = 1;
      if(dow==DayOfWeek.FRIDAY) dayToAdd = 3;
      else if(dow==DayOfWeek.SATURDAY) dayToAdd = 2;
      return temporal.plus(dayToAdd, ChronoUnit.DAYS);
  }
);

TemporalAdjuster nextWorkingDay = TemporalAdjusters.ofDateAdjuster(
    temporal -> {
        DayOfWeek dow = DayOfWeek.of(temporal.get(ChronoField.DAY_OF_WEEK));
        int dayToAdd = 1;
        if(dow==DayOfWeek.FRIDAY) dayToAdd = 3;
        else if(dow==DayOfWeek.SATURDAY) dayToAdd = 2;
        return temporal.plus(dayToAdd, ChronoUnit.DAYS);
    }
);
LocalDate date2 = LocalDate.now().with(nextWorkingDay);

LocalDate date = LocalDate.of(2014, 3, 18);
System.out.println(date.format(DateTimeFormatter.BASIC_ISO_DATE));
//20140318
System.out.println(date.format(DateTimeFormatter.ISO_LOCAL_DATE));
//2014-03-18

LocalDate date2 = LocalDate.parse("20140318", DateTimeFormatter.BASIC_ISO_DATE);
LocalDate date3 = LocalDate.parse("2014-03-18", DateTimeFormatter.ISO_LOCAL_DATE);
System.out.println(date2);
System.out.println(date3);

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy");
LocalDate date4 = LocalDate.now();
String formattedDate = date4.format(formatter);
System.out.println(formattedDate);
//21/01/2022

LocalDate date5 = LocalDate.parse(formattedDate, formatter);
System.out.println(date5);
//2022-01-21

DateTimeFormatter timeFomatterItalian = DateTimeFormatter.ofPattern("dd/MMMM/yyyy", Locale.ITALIAN);
String formattedDateItalian = LocalDate.now().format(timeFomatterItalian);

DateTimeFormatter timeFomatterKorean = DateTimeFormatter.ofPattern("dd/MMMM/yyyy", Locale.KOREAN);
String formattedDateKorean = LocalDate.now().format(timeFomatterKorean);

System.out.println(formattedDateItalian); //21/gennaio/2022
System.out.println(formattedDateKorean); //21/1월/2022

DateTimeFormatter koreanFormatter = new DateTimeFormatterBuilder()
        .appendLiteral("'")
        .appendText(ChronoField.YEAR)
        .appendLiteral(".")
        .appendText(ChronoField.MONTH_OF_YEAR)
        .appendLiteral(".")
        .appendText(ChronoField.DAY_OF_MONTH)
        .appendLiteral(".")
        .appendLiteral("(")
        .appendText(ChronoField.DAY_OF_WEEK)
        .appendLiteral(")")
        .parseCaseInsensitive()
        .toFormatter(Locale.KOREA);
String formattedDateKo2 = LocalDate.now().format(koreanFormatter);
System.out.println(formattedDateKo2);
//'2022.1월.21.(금요일)

ZoneId romeZone = ZoneId.of("Europe/Rome");
ZoneId korZone = ZoneId.of("Asia/Tokyo");
LocalDateTime dateTime = LocalDateTime.now();

ZonedDateTime zdt2 = dateTime.atZone(romeZone);
System.out.println(zdt2); //한국시간 기준 로마시간대로 변환해줌 > 왜?
zdt2 = dateTime.atZone(korZone);
System.out.println(zdt2); //한국시간대로 변환해줌

//호환성을 위해 Instant로 작업하는것이 유리
LocalDateTime dt = LocalDateTime.ofInstant(Instant.now(), ZoneOffset.UTC);
LocalDateTime dt2 = LocalDateTime.ofInstant(Instant.now(), ZoneId.of("Europe/Rome"));
LocalDateTime dt3 = LocalDateTime.ofInstant(Instant.now(), ZoneId.of("Asia/Tokyo"));
System.out.println(dt); //2022-01-21T10:47:21.983854600
System.out.println(dt2); //2022-01-21T11:47:21.983854600
System.out.println(dt3); //2022-01-21T11:47:21.983854600

LocalDate date = LocalDate.of(2014, Month.MARCH, 18);
JapaneseDate japaneseDate = JapaneseDate.from(date);
System.out.println(japaneseDate); //Japanese Heisei 26-03-18

HijrahDate ramadanDate = HijrahDate.now()
        .with(ChronoField.DAY_OF_MONTH, 1)
        .with(ChronoField.MONTH_OF_YEAR, 9);
System.out.println("Ramadan starts on " + IsoChronology.INSTANCE.date(ramadanDate)
        + " and ends on" + IsoChronology.INSTANCE.date(ramadanDate.with(TemporalAdjusters.lastDayOfMonth())));

Chronology japaneseChronology = Chronology.ofLocale(Locale.JAPAN);
ChronoLocalDate now = japaneseChronology.dateNow();
System.out.println(now);