Java: Класс LocalDate

Класс java.time.LocalDate представляет время с годом, месяцем и днем месяца. Например, 2015-08-25.

Для создания объекта класса, используется метод of():

LocalDate newYear2001 = LocalDate.of(2001, 1, 1);
LocalDate newYear2002 = LocalDate.of(2002, Month.JANUARY, 1);

Для создания объекта, отображающего текущую дату, используется метод now():

LocalDate today = LocalDate.now();

Следующий пример показывает получение года, месяца, дня месяца:

import java.time.DayOfWeek;
import java.time.LocalDate;
import java.time.Month;

public class LocalDateExample2 {
    public static void main(String[] args) {
        LocalDate today = LocalDate.now();

        int year = today.getYear();
        int month = today.getMonthValue();
        Month monthAsEnum = today.getMonth(); // как перечисление
        int dayYear = today.getDayOfYear();
        int dayMonth = today.getDayOfMonth();
        DayOfWeek dayWeekEnum = today.getDayOfWeek(); // как перечисление

        System.out.println("Год: " + year);
        System.out.println("Месяц: " + month);
        System.out.println("Название месяца: " + monthAsEnum);
        System.out.println("День в году: " + dayYear);
        System.out.println("День месяца: " + dayMonth);
        System.out.println("День недели: " + dayWeekEnum);
    }
}

Еще один вариант получение года, месяца, дня месяца:

import java.time.LocalDate;
import java.time.temporal.ChronoField;

public class LocalDateExample3 {
    public static void main(String[] args) {
        LocalDate today = LocalDate.now();

        int year = today.get(ChronoField.YEAR);
        int month = today.get(ChronoField.MONTH_OF_YEAR);
        int dayYear = today.get(ChronoField.DAY_OF_YEAR);
        int dayMonth = today.get(ChronoField.DAY_OF_MONTH);
        int dayWeek = today.get(ChronoField.DAY_OF_WEEK);

        System.out.println("Год: " + year);
        System.out.println("Месяц: " + month);
        System.out.println("День в году: " + dayYear);
        System.out.println("День месяца: " + dayMonth);
        System.out.println("День недели: " + dayWeek);
    }
}

Для сравнения дат используются методы isAfter(), isBefore(), equals(), isLeapYear():

import java.time.LocalDate;
import java.time.Month;

public class CompareLocalDateExample1 {
    public static void main(String[] args) {
        LocalDate newYear2001 = LocalDate.of(2001, 1, 1);
        LocalDate newYear2002 = LocalDate.of(2002, Month.JANUARY, 1);

        boolean after = newYear2001.isAfter(newYear2002);
        boolean before = newYear2001.isBefore(newYear2002);
        boolean equal = newYear2001.equals(newYear2002);
        boolean leapYear = newYear2001.isLeapYear();

        System.out.println("newYear2001.isAfter(newYear2002): " + after);
        System.out.println("newYear2001.isBefore(newYear2002): " + before);
        System.out.println("newYear2001.equals(newYear2002): " + equal);
        System.out.println("newYear2001.isLeapYear(): " + leapYear);
    }
}

Следующий пример показывает использование методов with() для изменения отдельно года, месяца, дня:

import java.time.LocalDate;
import java.time.temporal.ChronoField;

public class WithLocalDateExample {
    public static void main(String[] args) {
        LocalDate newYear2001 = LocalDate.of(2001, 1, 1);

        LocalDate newYear2003 = newYear2001.with(ChronoField.YEAR, 2003);
        LocalDate newYear2004 = newYear2001.withYear(2004);
        LocalDate december2001 = newYear2001.withMonth(12);
        LocalDate february2001 = newYear2001.withDayOfYear(32);
        LocalDate xmas2001 = newYear2001.withMonth(12).withDayOfMonth(25);

        System.out.println("newYear2003 " + newYear2003);
        System.out.println("newYear2004 " + newYear2004);
        System.out.println("december2001 " + december2001);
        System.out.println("february2001 " + february2001);
        System.out.println("xmas2001 " + xmas2001);
    }
}

Методы plus(), minus() используются для добавления или вычитания года, месяца или дня:

import java.time.LocalDate;
import java.time.temporal.ChronoUnit;

public class PlusMinusLocalDateExample {
    public static void main(String[] args) {
        LocalDate newYear2001 = LocalDate.of(2001, 1, 1);
        LocalDate newYear2005 = newYear2001.plusYears(4);
        LocalDate march2001 = newYear2001.plusMonths(2);
        LocalDate january15Year2001 = newYear2001.plusDays(14);
        LocalDate lastWeekJanuary2001 = newYear2001.plusWeeks(3);
        LocalDate newYear2006 = newYear2001.plus(5, ChronoUnit.YEARS);

        LocalDate newYear2000 = newYear2001.minusYears(1);
        LocalDate nov2000 = newYear2001.minusMonths(2);
        LocalDate dec30Year2000 = newYear2001.minusDays(2);
        LocalDate lastWeekDec2001 = newYear2001.minusWeeks(1);
        LocalDate newYear1999 = newYear2001.minus(2, ChronoUnit.YEARS);

        System.out.println("newYear2005: " + newYear2005);
        System.out.println("march2001: " + march2001);
        System.out.println("january15Year2001: " + january15Year2001);
        System.out.println("lastWeekJanuary2001: " + lastWeekJanuary2001);
        System.out.println("newYear2006: " + newYear2006);

        System.out.println("newYear2000: " + newYear2000);
        System.out.println("nov2000: " + nov2000);
        System.out.println("dec30Year2000: " + dec30Year2000);
        System.out.println("lastWeekDec2001: " + lastWeekDec2001);
        System.out.println("newYear1999: " + newYear1999);
    }
}