Java : LocalDateTime (日時・タイムゾーンなし) - API使用例

LocalDateTime (Java SE 21 & JDK 21) の使い方まとめです。
だいたいのメソッドを網羅済みです。
API仕様書のおともにどうぞ。

概要

ISO-8601暦体系のタイムゾーンのない日付/時間、2007-12-03T10:15:30など。

クラス構成

LocalDateTime は日時を表すクラスです。
タイムゾーン情報は持ちません。

日時は、

日付 (年と月と日)
時刻 (時と分と秒とナノ秒)

で構成されます。

インスタンスの生成には of メソッドを使います。

フィールド

static final LocalDateTime MAX

サポートされている最大のLocalDateTimeである「+999999999-12-31T23:59:59.999999999」。

System.out.println(LocalDateTime.MAX); // +999999999-12-31T23:59:59.999999999

static final LocalDateTime MIN

サポートされている最小のLocalDateTimeである「-999999999-01-01T00:00:00」。

System.out.println(LocalDateTime.MIN); // -999999999-01-01T00:00

メソッド

Temporal adjustInto (Temporal temporal)

指定された時間的オブジェクトをこのオブジェクトと同じ日付と時間になるように調整します。

final var zone = ZoneId.systemDefault();
System.out.println(zone); // Asia/Tokyo

final var temporal = ZonedDateTime.of(2100, 1, 1, 0, 0, 0, 0, zone);
System.out.println(temporal); // 2100-01-01T00:00+09:00[Asia/Tokyo]

final var dateTime = LocalDateTime.of(1900, 4, 15, 1, 2, 3, 0);
System.out.println(dateTime); // 1900-04-15T01:02:03

final var ret = dateTime.adjustInto(temporal);
System.out.println(ret); // 1900-04-15T01:02:03+09:00[Asia/Tokyo]

final var offset = ZoneOffset.ofHours(-8);
System.out.println(offset); // -08:00

final var temporal = OffsetDateTime.of(2100, 1, 2, 3, 4, 5, 678000000, offset);
System.out.println(temporal); // 2100-01-02T03:04:05.678-08:00

final var dateTime = LocalDateTime.of(2500, 4, 14, 0, 0);
System.out.println(dateTime); // 2500-04-14T00:00

final var ret = dateTime.adjustInto(temporal);
System.out.println(ret); // 2500-04-14T00:00-08:00

OffsetDateTime atOffset (ZoneOffset offset)

この日付/時間をオフセットと組み合せてOffsetDateTimeを作成します。

final var dateTime = LocalDateTime.of(2100, 4, 14, 15, 20);
System.out.println(dateTime); // 2100-04-14T15:20

final var ret1 = dateTime.atOffset(ZoneOffset.UTC);
System.out.println(ret1); // 2100-04-14T15:20Z

final var ret2 = dateTime.atOffset(ZoneOffset.ofHours(9));
System.out.println(ret2); // 2100-04-14T15:20+09:00

final var ret3 = dateTime.atOffset(ZoneOffset.ofHoursMinutes(-7, -30));
System.out.println(ret3); // 2100-04-14T15:20-07:30

ZonedDateTime atZone (ZoneId zone)

この日付/時間をタイムゾーンと組み合せてZonedDateTimeを作成します。

final var dateTime = LocalDateTime.of(2100, 4, 14, 15, 20);
System.out.println(dateTime); // 2100-04-14T15:20

final var ret1 = dateTime.atZone(ZoneId.systemDefault());
System.out.println(ret1); // 2100-04-14T15:20+09:00[Asia/Tokyo]

final var ret2 = dateTime.atZone(ZoneId.of("America/Los_Angeles"));
System.out.println(ret2); // 2100-04-14T15:20-07:00[America/Los_Angeles]

final var ret3 = dateTime.atZone(ZoneOffset.UTC);
System.out.println(ret3); // 2100-04-14T15:20Z

int compareTo (ChronoLocalDateTime<?> other)

この日付/時間を別の日付/時間と比較します。

final var dateTime1 = LocalDateTime.of(2100, 1, 1, 0, 0);
final var dateTime2 = LocalDateTime.of(2100, 1, 1, 0, 0);

System.out.println(dateTime1); // 2100-01-01T00:00
System.out.println(dateTime2); // 2100-01-01T00:00
System.out.println(dateTime1.compareTo(dateTime2)); // 0

final var dateTime1 = LocalDateTime.of(2100, 4, 14, 15, 20);
final var dateTime2 = LocalDateTime.of(2100, 4, 14, 15, 21);

System.out.println(dateTime1); // 2100-04-14T15:20
System.out.println(dateTime2); // 2100-04-14T15:21
System.out.println(dateTime1.compareTo(dateTime2)); // -1

final var dateTime1 = LocalDateTime.of(2100, 4, 15, 0, 0);
final var dateTime2 = LocalDateTime.of(2100, 4, 14, 0, 0);

System.out.println(dateTime1); // 2100-04-15T00:00
System.out.println(dateTime2); // 2100-04-14T00:00
System.out.println(dateTime1.compareTo(dateTime2)); // 1

final var dateTime1 = LocalDateTime.of(2100, 1, 1, 0, 0);
final var dateTime2 = LocalDateTime.of(1900, 12, 30, 23, 59);

System.out.println(dateTime1); // 2100-01-01T00:00
System.out.println(dateTime2); // 1900-12-30T23:59
System.out.println(dateTime1.compareTo(dateTime2)); // 200

final var dateTime1 = LocalDateTime.of(2099, 1, 1, 0, 0, 1);
final var dateTime2 = LocalDateTime.of(2099, 1, 1, 0, 0);

System.out.println(dateTime1); // 2099-01-01T00:00:01
System.out.println(dateTime2); // 2099-01-01T00:00
System.out.println(dateTime1.compareTo(dateTime2)); // 1

final var dateTime1 = LocalDateTime.of(2100, 4, 13, 0, 0, 0, 123);
final var dateTime2 = LocalDateTime.of(2100, 4, 13, 0, 0, 0, 456);

System.out.println(dateTime1); // 2100-04-13T00:00:00.000000123
System.out.println(dateTime2); // 2100-04-13T00:00:00.000000456
System.out.println(dateTime1.compareTo(dateTime2)); // -1

boolean equals (Object obj)

この日付/時間が別の日付/時間と等しいかどうかをチェックします。

final var dateTime1 = LocalDateTime.of(2100, 1, 1, 0, 0);
final var dateTime2 = LocalDateTime.of(2100, 1, 1, 0, 0);

System.out.println(dateTime1); // 2100-01-01T00:00
System.out.println(dateTime2); // 2100-01-01T00:00
System.out.println(dateTime1.equals(dateTime2)); // true

final var dateTime1 = LocalDateTime.of(2100, 4, 14, 15, 20);
final var dateTime2 = LocalDateTime.of(2100, 4, 14, 15, 21);

System.out.println(dateTime1); // 2100-04-14T15:20
System.out.println(dateTime2); // 2100-04-14T15:21
System.out.println(dateTime1.equals(dateTime2)); // false

final var dateTime1 = LocalDateTime.of(2100, 4, 15, 0, 0);
final var dateTime2 = LocalDateTime.of(2100, 4, 14, 0, 0);

System.out.println(dateTime1); // 2100-04-15T00:00
System.out.println(dateTime2); // 2100-04-14T00:00
System.out.println(dateTime1.equals(dateTime2)); // false

final var dateTime1 = LocalDateTime.of(2100, 1, 1, 0, 0);
final var dateTime2 = LocalDateTime.of(1900, 12, 30, 23, 59);

System.out.println(dateTime1); // 2100-01-01T00:00
System.out.println(dateTime2); // 1900-12-30T23:59
System.out.println(dateTime1.equals(dateTime2)); // false

final var dateTime1 = LocalDateTime.of(2099, 1, 1, 0, 0, 1);
final var dateTime2 = LocalDateTime.of(2099, 1, 1, 0, 0);

System.out.println(dateTime1); // 2099-01-01T00:00:01
System.out.println(dateTime2); // 2099-01-01T00:00
System.out.println(dateTime1.equals(dateTime2)); // false

final var dateTime1 = LocalDateTime.of(2100, 4, 13, 0, 0, 0, 123);
final var dateTime2 = LocalDateTime.of(2100, 4, 13, 0, 0, 0, 456);

System.out.println(dateTime1); // 2100-04-13T00:00:00.000000123
System.out.println(dateTime2); // 2100-04-13T00:00:00.000000456
System.out.println(dateTime1.equals(dateTime2)); // false

String format (DateTimeFormatter formatter)

指定されたフォーマッタを使用してこの日付/時間を書式設定します。

final var dateTime = LocalDateTime.of(2100, 4, 7, 13, 30, 45);
System.out.println(dateTime); // 2100-04-07T13:30:45

{
    final var ret1 = dateTime.format(
            DateTimeFormatter.ISO_LOCAL_DATE_TIME);
    System.out.println(ret1); // 2100-04-07T13:30:45

    final var ret2 = dateTime.format(
            DateTimeFormatter.ofPattern("yyyy年MM月dd日(E) HH時mm分ss秒"));
    System.out.println(ret2); // 2100年04月07日(水) 13時30分45秒
}
{
    System.out.println(Locale.getDefault().toLanguageTag()); // ja-JP

    final var ret1 = dateTime.format(
            DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM));
    System.out.println(ret1); // 2100/04/07 13:30:45

    final var ret2 = dateTime.format(
            DateTimeFormatter.ofLocalizedDateTime(FormatStyle.SHORT));
    System.out.println(ret2); // 2100/04/07 13:30

    try {
        final var ret = dateTime.format(
                DateTimeFormatter.ofLocalizedDateTime(FormatStyle.LONG));
    } catch (DateTimeException e) {
        System.out.println("DateTimeException! : " + e.getMessage());
    }

    // 結果
    // ↓
    //DateTimeException! : Unable to extract ZoneId from temporal 2100-04-07T13:30:45
}

static LocalDateTime from (TemporalAccessor temporal)

時間的オブジェクトからLocalDateTimeのインスタンスを取得します。

final var zone = ZoneId.systemDefault();
System.out.println(zone); // Asia/Tokyo

final var temporal = ZonedDateTime.of(2100, 4, 13, 12, 30, 45, 1234, zone);
System.out.println(temporal); // 2100-04-13T12:30:45.000001234+09:00[Asia/Tokyo]

System.out.println(LocalDateTime.from(temporal)); // 2100-04-13T12:30:45.000001234

final var offset = ZoneOffset.ofHours(-8);
System.out.println(offset); // -08:00

final var temporal = OffsetDateTime.of(1900, 1, 2, 12, 30, 0, 0, offset);
System.out.println(temporal); // 1900-01-02T12:30-08:00

System.out.println(LocalDateTime.from(temporal)); // 1900-01-02T12:30

int get (TemporalField field)

指定されたフィールドの値をこの日付/時間からintとして取得します。

final var dateTime = LocalDateTime.of(2100, 4, 13, 12, 30, 45, 123);
System.out.println(dateTime); // 2100-04-13T12:30:45.000000123

System.out.println(dateTime.isSupported(ChronoField.YEAR)); // true
System.out.println(dateTime.get(ChronoField.YEAR)); // 2100

System.out.println(dateTime.isSupported(ChronoField.MONTH_OF_YEAR)); // true
System.out.println(dateTime.get(ChronoField.MONTH_OF_YEAR)); // 4

System.out.println(dateTime.isSupported(ChronoField.DAY_OF_MONTH)); // true
System.out.println(dateTime.get(ChronoField.DAY_OF_MONTH)); // 13

System.out.println(dateTime.isSupported(ChronoField.HOUR_OF_DAY)); // true
System.out.println(dateTime.get(ChronoField.HOUR_OF_DAY)); // 12

System.out.println(dateTime.isSupported(ChronoField.MINUTE_OF_HOUR)); // true
System.out.println(dateTime.get(ChronoField.MINUTE_OF_HOUR)); // 30

System.out.println(dateTime.isSupported(ChronoField.SECOND_OF_MINUTE)); // true
System.out.println(dateTime.get(ChronoField.SECOND_OF_MINUTE)); // 45

System.out.println(dateTime.isSupported(ChronoField.NANO_OF_SECOND)); // true
System.out.println(dateTime.get(ChronoField.NANO_OF_SECOND)); // 123

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00

System.out.println(dateTime.isSupported(ChronoField.OFFSET_SECONDS)); // false

try {
    final var ret = dateTime.get(ChronoField.OFFSET_SECONDS);
} catch (UnsupportedTemporalTypeException e) {
    System.out.println("UnsupportedTemporalTypeException! : " + e.getMessage());
}

// 結果
// ↓
//UnsupportedTemporalTypeException! : Unsupported field: OffsetSeconds

int getDayOfMonth ()

「月の日」フィールドを取得します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00
System.out.println(dateTime.getDayOfMonth()); // 1

final var dateTime = LocalDateTime.of(2100, 1, 2, 0, 0);
System.out.println(dateTime); // 2100-01-02T00:00
System.out.println(dateTime.getDayOfMonth()); // 2

final var dateTime = LocalDateTime.of(2100, 1, 3, 0, 0);
System.out.println(dateTime); // 2100-01-03T00:00
System.out.println(dateTime.getDayOfMonth()); // 3

final var dateTime = LocalDateTime.of(2100, 1, 30, 0, 0);
System.out.println(dateTime); // 2100-01-30T00:00
System.out.println(dateTime.getDayOfMonth()); // 30

final var dateTime = LocalDateTime.of(2100, 1, 31, 0, 0);
System.out.println(dateTime); // 2100-01-31T00:00
System.out.println(dateTime.getDayOfMonth()); // 31

final var dateTime = LocalDateTime.of(2100, 2, 1, 0, 0);
System.out.println(dateTime); // 2100-02-01T00:00
System.out.println(dateTime.getDayOfMonth()); // 1

DayOfWeek getDayOfWeek ()

列挙型DayOfWeekである曜日フィールドを取得します。

final var dateTime = LocalDateTime.of(2100, 1, 3, 0, 0);
System.out.println(dateTime); // 2100-01-03T00:00
System.out.println(dateTime.getDayOfWeek()); // SUNDAY

final var dateTime = LocalDateTime.of(2100, 1, 4, 0, 0);
System.out.println(dateTime); // 2100-01-04T00:00
System.out.println(dateTime.getDayOfWeek()); // MONDAY

final var dateTime = LocalDateTime.of(2100, 1, 5, 0, 0);
System.out.println(dateTime); // 2100-01-05T00:00
System.out.println(dateTime.getDayOfWeek()); // TUESDAY

final var dateTime = LocalDateTime.of(2100, 1, 6, 0, 0);
System.out.println(dateTime); // 2100-01-06T00:00
System.out.println(dateTime.getDayOfWeek()); // WEDNESDAY

final var dateTime = LocalDateTime.of(2100, 1, 7, 0, 0);
System.out.println(dateTime); // 2100-01-07T00:00
System.out.println(dateTime.getDayOfWeek()); // THURSDAY

final var dateTime = LocalDateTime.of(2100, 1, 8, 0, 0);
System.out.println(dateTime); // 2100-01-08T00:00
System.out.println(dateTime.getDayOfWeek()); // FRIDAY

final var dateTime = LocalDateTime.of(2100, 1, 9, 0, 0);
System.out.println(dateTime); // 2100-01-09T00:00
System.out.println(dateTime.getDayOfWeek()); // SATURDAY

final var dateTime = LocalDateTime.of(2100, 1, 10, 0, 0);
System.out.println(dateTime); // 2100-01-10T00:00
System.out.println(dateTime.getDayOfWeek()); // SUNDAY

int getDayOfYear ()

「年の日」フィールドを取得します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00
System.out.println(dateTime.getDayOfYear()); // 1

final var dateTime = LocalDateTime.of(2100, 1, 2, 0, 0);
System.out.println(dateTime); // 2100-01-02T00:00
System.out.println(dateTime.getDayOfYear()); // 2

final var dateTime = LocalDateTime.of(2100, 1, 30, 0, 0);
System.out.println(dateTime); // 2100-01-30T00:00
System.out.println(dateTime.getDayOfYear()); // 30

final var dateTime = LocalDateTime.of(2100, 1, 31, 0, 0);
System.out.println(dateTime); // 2100-01-31T00:00
System.out.println(dateTime.getDayOfYear()); // 31

final var dateTime = LocalDateTime.of(2100, 2, 1, 0, 0);
System.out.println(dateTime); // 2100-02-01T00:00
System.out.println(dateTime.getDayOfYear()); // 32

final var dateTime = LocalDateTime.of(2100, 2, 2, 0, 0);
System.out.println(dateTime); // 2100-02-02T00:00
System.out.println(dateTime.getDayOfYear()); // 33

final var dateTime = LocalDateTime.of(2100, 12, 31, 0, 0);
System.out.println(dateTime); // 2100-12-31T00:00
System.out.println(dateTime.getDayOfYear()); // 365

final var dateTime = LocalDateTime.of(2101, 1, 1, 0, 0);
System.out.println(dateTime); // 2101-01-01T00:00
System.out.println(dateTime.getDayOfYear()); // 1

int getHour ()

時フィールドを取得します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 14, 30, 15);
System.out.println(dateTime); // 2100-01-01T14:30:15
System.out.println(dateTime.getHour()); // 14

long getLong (TemporalField field)

指定されたフィールドの値をこの日付/時間からlongとして取得します。

final var dateTime = LocalDateTime.of(2100, 4, 13, 12, 30, 45, 123);
System.out.println(dateTime); // 2100-04-13T12:30:45.000000123

System.out.println(dateTime.getLong(ChronoField.YEAR)); // 2100
System.out.println(dateTime.getLong(ChronoField.MONTH_OF_YEAR)); // 4
System.out.println(dateTime.getLong(ChronoField.DAY_OF_MONTH)); // 13
System.out.println(dateTime.getLong(ChronoField.HOUR_OF_DAY)); // 12
System.out.println(dateTime.getLong(ChronoField.MINUTE_OF_HOUR)); // 30
System.out.println(dateTime.getLong(ChronoField.SECOND_OF_MINUTE)); // 45
System.out.println(dateTime.getLong(ChronoField.NANO_OF_SECOND)); // 123

int getMinute ()

分フィールドを取得します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30, 15);
System.out.println(dateTime); // 2100-01-01T13:30:15
System.out.println(dateTime.getMinute()); // 30

Month getMonth ()

列挙型Monthを使用して、月フィールドを取得します。

final var dateTime = LocalDateTime.of(2100, 1, 15, 0, 0);
System.out.println(dateTime); // 2100-01-15T00:00
System.out.println(dateTime.getMonth()); // JANUARY

final var dateTime = LocalDateTime.of(2100, 2, 15, 0, 0);
System.out.println(dateTime); // 2100-02-15T00:00
System.out.println(dateTime.getMonth()); // FEBRUARY

final var dateTime = LocalDateTime.of(2100, 3, 15, 0, 0);
System.out.println(dateTime); // 2100-03-15T00:00
System.out.println(dateTime.getMonth()); // MARCH

final var dateTime = LocalDateTime.of(2100, 12, 15, 0, 0);
System.out.println(dateTime); // 2100-12-15T00:00
System.out.println(dateTime.getMonth()); // DECEMBER

final var dateTime = LocalDateTime.of(2101, 1, 1, 0, 0);
System.out.println(dateTime); // 2101-01-01T00:00
System.out.println(dateTime.getMonth()); // JANUARY

int getMonthValue ()

月フィールドを取得します(1-12)。

final var dateTime = LocalDateTime.of(2100, 1, 15, 0, 0);
System.out.println(dateTime); // 2100-01-15T00:00
System.out.println(dateTime.getMonthValue()); // 1

final var dateTime = LocalDateTime.of(2100, 2, 15, 0, 0);
System.out.println(dateTime); // 2100-02-15T00:00
System.out.println(dateTime.getMonthValue()); // 2

final var dateTime = LocalDateTime.of(2100, 3, 15, 0, 0);
System.out.println(dateTime); // 2100-03-15T00:00
System.out.println(dateTime.getMonthValue()); // 3

final var dateTime = LocalDateTime.of(2100, 12, 15, 0, 0);
System.out.println(dateTime); // 2100-12-15T00:00
System.out.println(dateTime.getMonthValue()); // 12

final var dateTime = LocalDateTime.of(2101, 1, 1, 0, 0);
System.out.println(dateTime); // 2101-01-01T00:00
System.out.println(dateTime.getMonthValue()); // 1

int getNano ()

ナノ秒フィールドを取得します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30, 15);
System.out.println(dateTime); // 2100-01-01T13:30:15
System.out.println(dateTime.getNano()); // 0

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30, 15, 123456789);
System.out.println(dateTime); // 2100-01-01T13:30:15.123456789
System.out.println(dateTime.getNano()); // 123456789

int getSecond ()

秒フィールドを取得します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30, 15);
System.out.println(dateTime); // 2100-01-01T13:30:15
System.out.println(dateTime.getSecond()); // 15

int getYear ()

年フィールドを取得します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00
System.out.println(dateTime.getYear()); // 2100

final var dateTime = LocalDateTime.of(1900, 1, 1, 0, 0);
System.out.println(dateTime); // 1900-01-01T00:00
System.out.println(dateTime.getYear()); // 1900

final var dateTime = LocalDateTime.of(-3000, 1, 1, 0, 0);
System.out.println(dateTime); // -3000-01-01T00:00
System.out.println(dateTime.getYear()); // -3000

final var dateTime = LocalDateTime.of(9999, 1, 1, 0, 0);
System.out.println(dateTime); // 9999-01-01T00:00
System.out.println(dateTime.getYear()); // 9999

int hashCode ()

この日付/時間のハッシュ・コード。

final var ret1 = LocalDateTime.of(2100, 1, 1, 0, 0).hashCode();
System.out.println(ret1); // 4302913

final var ret2 = LocalDateTime.of(1900, 4, 13, 12, 30, 40, 123).hashCode();
System.out.println(ret2); // -1324865152

final var ret3 = LocalDateTime.MIN.hashCode();
System.out.println(ret3); // -304793535

final var ret4 = LocalDateTime.MAX.hashCode();
System.out.println(ret4); // 2090566260

boolean isAfter (ChronoLocalDateTime<?> other)

この日付/時間が、指定された日付/時間より後にあるかどうかをチェックします。

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00

final var dateTime2 = LocalDateTime.of(2099, 1, 1, 0, 0);
final var dateTime3 = LocalDateTime.of(2100, 1, 1, 0, 0);
final var dateTime4 = LocalDateTime.of(2101, 1, 1, 0, 0);

System.out.println(dateTime2); // 2099-01-01T00:00
System.out.println(dateTime3); // 2100-01-01T00:00
System.out.println(dateTime4); // 2101-01-01T00:00

System.out.println(dateTime.isAfter(dateTime2)); // true
System.out.println(dateTime.isAfter(dateTime3)); // false
System.out.println(dateTime.isAfter(dateTime4)); // false

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 0);
System.out.println(dateTime); // 2100-01-01T13:00

final var dateTime2 = LocalDateTime.of(2100, 1, 1, 13, 0);
final var dateTime3 = LocalDateTime.of(2100, 1, 1, 13, 0, 1);
final var dateTime4 = LocalDateTime.of(2100, 1, 1, 12, 59);

System.out.println(dateTime2); // 2100-01-01T13:00
System.out.println(dateTime3); // 2100-01-01T13:00:01
System.out.println(dateTime4); // 2100-01-01T12:59

System.out.println(dateTime.isAfter(dateTime2)); // false
System.out.println(dateTime.isAfter(dateTime3)); // false
System.out.println(dateTime.isAfter(dateTime4)); // true

boolean isBefore (ChronoLocalDateTime<?> other)

この日付/時間が、指定された日付/時間より前にあるかどうかをチェックします。

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00

final var dateTime2 = LocalDateTime.of(2099, 1, 1, 0, 0);
final var dateTime3 = LocalDateTime.of(2100, 1, 1, 0, 0);
final var dateTime4 = LocalDateTime.of(2101, 1, 1, 0, 0);

System.out.println(dateTime2); // 2099-01-01T00:00
System.out.println(dateTime3); // 2100-01-01T00:00
System.out.println(dateTime4); // 2101-01-01T00:00

System.out.println(dateTime.isBefore(dateTime2)); // false
System.out.println(dateTime.isBefore(dateTime3)); // false
System.out.println(dateTime.isBefore(dateTime4)); // true

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 0);
System.out.println(dateTime); // 2100-01-01T13:00

final var dateTime2 = LocalDateTime.of(2100, 1, 1, 13, 0);
final var dateTime3 = LocalDateTime.of(2100, 1, 1, 13, 0, 1);
final var dateTime4 = LocalDateTime.of(2100, 1, 1, 12, 59);

System.out.println(dateTime2); // 2100-01-01T13:00
System.out.println(dateTime3); // 2100-01-01T13:00:01
System.out.println(dateTime4); // 2100-01-01T12:59

System.out.println(dateTime.isBefore(dateTime2)); // false
System.out.println(dateTime.isBefore(dateTime3)); // true
System.out.println(dateTime.isBefore(dateTime4)); // false

boolean isEqual (ChronoLocalDateTime<?> other)

この日付/時間が、指定された日付/時間と等しいかどうかをチェックします。

final var dateTime1 = LocalDateTime.of(2100, 6, 30, 12, 0);
final var dateTime2 = LocalDateTime.of(2100, 7, 1, 12, 0);

System.out.println(dateTime1); // 2100-06-30T12:00
System.out.println(dateTime2); // 2100-07-01T12:00

System.out.println(dateTime1.isEqual(dateTime2)); // false
System.out.println(dateTime1.isEqual(dateTime1)); // true
System.out.println(dateTime2.isEqual(dateTime1)); // false

final var dateTime1 = LocalDateTime.of(1900, 1, 1, 13, 0);
final var dateTime2 = LocalDateTime.of(1900, 1, 1, 12, 59);

System.out.println(dateTime1); // 1900-01-01T13:00
System.out.println(dateTime2); // 1900-01-01T12:59

System.out.println(dateTime1.isEqual(dateTime2)); // false
System.out.println(dateTime1.isEqual(dateTime1)); // true
System.out.println(dateTime2.isEqual(dateTime1)); // false

boolean isSupported (TemporalField field)

指定されたフィールドがサポートされているかどうかをチェックします。

final var dateTime = LocalDateTime.of(2100, 4, 13, 12, 30, 45, 123);
System.out.println(dateTime); // 2100-04-13T12:30:45.000000123

System.out.println(dateTime.isSupported(ChronoField.YEAR)); // true
System.out.println(dateTime.get(ChronoField.YEAR)); // 2100

System.out.println(dateTime.isSupported(ChronoField.MONTH_OF_YEAR)); // true
System.out.println(dateTime.get(ChronoField.MONTH_OF_YEAR)); // 4

System.out.println(dateTime.isSupported(ChronoField.DAY_OF_MONTH)); // true
System.out.println(dateTime.get(ChronoField.DAY_OF_MONTH)); // 13

System.out.println(dateTime.isSupported(ChronoField.HOUR_OF_DAY)); // true
System.out.println(dateTime.get(ChronoField.HOUR_OF_DAY)); // 12

System.out.println(dateTime.isSupported(ChronoField.MINUTE_OF_HOUR)); // true
System.out.println(dateTime.get(ChronoField.MINUTE_OF_HOUR)); // 30

System.out.println(dateTime.isSupported(ChronoField.SECOND_OF_MINUTE)); // true
System.out.println(dateTime.get(ChronoField.SECOND_OF_MINUTE)); // 45

System.out.println(dateTime.isSupported(ChronoField.NANO_OF_SECOND)); // true
System.out.println(dateTime.get(ChronoField.NANO_OF_SECOND)); // 123

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00

System.out.println(dateTime.isSupported(ChronoField.OFFSET_SECONDS)); // false

try {
    final var ret = dateTime.get(ChronoField.OFFSET_SECONDS);
} catch (UnsupportedTemporalTypeException e) {
    System.out.println("UnsupportedTemporalTypeException! : " + e.getMessage());
}

// 結果
// ↓
//UnsupportedTemporalTypeException! : Unsupported field: OffsetSeconds

boolean isSupported (TemporalUnit unit)

指定された単位がサポートされているかどうかをチェックします。

final var dateTime = LocalDateTime.of(2100, 4, 13, 12, 30, 45, 123);
System.out.println(dateTime); // 2100-04-13T12:30:45.000000123

System.out.println(dateTime.isSupported(ChronoUnit.YEARS)); // true
System.out.println(dateTime.isSupported(ChronoUnit.MONTHS)); // true
System.out.println(dateTime.isSupported(ChronoUnit.WEEKS)); // true
System.out.println(dateTime.isSupported(ChronoUnit.DAYS)); // true

System.out.println(dateTime.isSupported(ChronoUnit.HOURS)); // true
System.out.println(dateTime.isSupported(ChronoUnit.MINUTES)); // true
System.out.println(dateTime.isSupported(ChronoUnit.SECONDS)); // true
System.out.println(dateTime.isSupported(ChronoUnit.NANOS)); // true

System.out.println(dateTime.isSupported(ChronoUnit.FOREVER)); // false

LocalDateTime minus (long amountToSubtract, TemporalUnit unit)

指定された量を減算した、この日付/時間のコピーを返します。

final var dateTime = LocalDateTime.of(2100, 4, 13, 0, 0);
System.out.println(dateTime); // 2100-04-13T00:00

final var ret1 = dateTime.minus(1, ChronoUnit.YEARS);
System.out.println(ret1); // 2099-04-13T00:00

final var ret2 = dateTime.minus(2, ChronoUnit.MONTHS);
System.out.println(ret2); // 2100-02-13T00:00

final var ret3 = dateTime.minus(3, ChronoUnit.DAYS);
System.out.println(ret3); // 2100-04-10T00:00

final var dateTime = LocalDateTime.of(2100, 1, 1, 10, 20, 30, 123);
System.out.println(dateTime); // 2100-01-01T10:20:30.000000123

final var ret1 = dateTime.minus(1, ChronoUnit.HOURS);
System.out.println(ret1); // 2100-01-01T09:20:30.000000123

final var ret2 = dateTime.minus(2, ChronoUnit.MINUTES);
System.out.println(ret2); // 2100-01-01T10:18:30.000000123

final var ret3 = dateTime.minus(3, ChronoUnit.SECONDS);
System.out.println(ret3); // 2100-01-01T10:20:27.000000123

final var ret4 = dateTime.minus(4, ChronoUnit.NANOS);
System.out.println(ret4); // 2100-01-01T10:20:30.000000119

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00

final var ret1 = dateTime.minus(1, ChronoUnit.HOURS);
System.out.println(ret1); // 2099-12-31T23:00

final var ret2 = dateTime.minus(365, ChronoUnit.DAYS);
System.out.println(ret2); // 2099-01-01T00:00

final var ret3 = dateTime.minus(3000, ChronoUnit.YEARS);
System.out.println(ret3); // -0900-01-01T00:00

LocalDateTime minus (TemporalAmount amountToSubtract)

指定された量を減算した、この日付/時間のコピーを返します。

final var dateTime = LocalDateTime.of(2100, 4, 13, 0, 0);
System.out.println(dateTime); // 2100-04-13T00:00

final var ret1 = dateTime.minus(Period.ofYears(1));
System.out.println(ret1); // 2099-04-13T00:00

final var ret2 = dateTime.minus(Period.ofMonths(2));
System.out.println(ret2); // 2100-02-13T00:00

final var ret3 = dateTime.minus(Period.ofDays(3));
System.out.println(ret3); // 2100-04-10T00:00

final var dateTime = LocalDateTime.of(2100, 1, 1, 10, 20, 30, 123);
System.out.println(dateTime); // 2100-01-01T10:20:30.000000123

final var ret1 = dateTime.minus(Duration.ofHours(1));
System.out.println(ret1); // 2100-01-01T09:20:30.000000123

final var ret2 = dateTime.minus(Duration.ofMinutes(2));
System.out.println(ret2); // 2100-01-01T10:18:30.000000123

final var ret3 = dateTime.minus(Duration.ofSeconds(3));
System.out.println(ret3); // 2100-01-01T10:20:27.000000123

final var ret4 = dateTime.minus(Duration.ofNanos(4));
System.out.println(ret4); // 2100-01-01T10:20:30.000000119

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00

final var ret1 = dateTime.minus(Duration.ofHours(1));
System.out.println(ret1); // 2099-12-31T23:00

final var ret2 = dateTime.minus(Period.ofDays(365));
System.out.println(ret2); // 2099-01-01T00:00

final var ret3 = dateTime.minus(Period.ofYears(3000));
System.out.println(ret3); // -0900-01-01T00:00

LocalDateTime minusDays (long days)

指定された日数を減算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 5, 20, 0, 0);
System.out.println(dateTime); // 2100-05-20T00:00

System.out.println(dateTime.minusDays(1)); // 2100-05-19T00:00
System.out.println(dateTime.minusDays(2)); // 2100-05-18T00:00
System.out.println(dateTime.minusDays(20)); // 2100-04-30T00:00
System.out.println(dateTime.minusDays(365)); // 2099-05-20T00:00

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0);
System.out.println(dateTime); // 2100-01-01T00:00

System.out.println(dateTime.minusDays(1)); // 2099-12-31T00:00

LocalDateTime minusHours (long hours)

指定された時間数を減算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30, 15);
System.out.println(dateTime); // 2100-01-01T13:30:15

System.out.println(dateTime.minusHours(1)); // 2100-01-01T12:30:15
System.out.println(dateTime.minusHours(2)); // 2100-01-01T11:30:15
System.out.println(dateTime.minusHours(13)); // 2100-01-01T00:30:15
System.out.println(dateTime.minusHours(14)); // 2099-12-31T23:30:15

LocalDateTime minusMinutes (long minutes)

指定された分数を減算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30);
System.out.println(dateTime); // 2100-01-01T13:30

System.out.println(dateTime.minusMinutes(1)); // 2100-01-01T13:29
System.out.println(dateTime.minusMinutes(2)); // 2100-01-01T13:28
System.out.println(dateTime.minusMinutes(30)); // 2100-01-01T13:00
System.out.println(dateTime.minusMinutes(31)); // 2100-01-01T12:59
System.out.println(dateTime.minusMinutes(60 * 14)); // 2099-12-31T23:30

LocalDateTime minusMonths (long months)

指定された月数を減算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 5, 20, 0, 0);
System.out.println(dateTime); // 2100-05-20T00:00

System.out.println(dateTime.minusMonths(1)); // 2100-04-20T00:00
System.out.println(dateTime.minusMonths(2)); // 2100-03-20T00:00
System.out.println(dateTime.minusMonths(12)); // 2099-05-20T00:00

final var dateTime = LocalDateTime.of(2101, 3, 31, 0, 0);
System.out.println(dateTime); // 2101-03-31T00:00

System.out.println(dateTime.minusMonths(1)); // 2101-02-28T00:00

LocalDateTime minusNanos (long nanos)

指定されたナノ秒数を減算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30, 15, 123);
System.out.println(dateTime); // 2100-01-01T13:30:15.000000123

System.out.println(dateTime.minusNanos(1)); // 2100-01-01T13:30:15.000000122
System.out.println(dateTime.minusNanos(2)); // 2100-01-01T13:30:15.000000121
System.out.println(dateTime.minusNanos(123)); // 2100-01-01T13:30:15
System.out.println(dateTime.minusNanos(124)); // 2100-01-01T13:30:14.999999999

LocalDateTime minusSeconds (long seconds)

指定された秒数を減算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30, 15);
System.out.println(dateTime); // 2100-01-01T13:30:15

System.out.println(dateTime.minusSeconds(1)); // 2100-01-01T13:30:14
System.out.println(dateTime.minusSeconds(2)); // 2100-01-01T13:30:13
System.out.println(dateTime.minusSeconds(15)); // 2100-01-01T13:30
System.out.println(dateTime.minusSeconds(16)); // 2100-01-01T13:29:59
System.out.println(dateTime.minusSeconds(60 * 60)); // 2100-01-01T12:30:15
System.out.println(dateTime.minusSeconds(60 * 60 * 24)); // 2099-12-31T13:30:15

LocalDateTime minusWeeks (long weeks)

指定された週数を減算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 5, 20, 0, 0);
System.out.println(dateTime); // 2100-05-20T00:00

System.out.println(dateTime.minusWeeks(1)); // 2100-05-13T00:00
System.out.println(dateTime.minusWeeks(2)); // 2100-05-06T00:00
System.out.println(dateTime.minusWeeks(20)); // 2099-12-31T00:00
System.out.println(dateTime.minusWeeks(100)); // 2098-06-19T00:00

final var dateTime = LocalDateTime.of(2100, 1, 7, 0, 0);
System.out.println(dateTime); // 2100-01-07T00:00

System.out.println(dateTime.minusWeeks(1)); // 2099-12-31T00:00

LocalDateTime minusYears (long years)

指定された年数を減算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2103, 5, 20, 0, 0);
System.out.println(dateTime); // 2103-05-20T00:00

System.out.println(dateTime.minusYears(1)); // 2102-05-20T00:00
System.out.println(dateTime.minusYears(2)); // 2101-05-20T00:00
System.out.println(dateTime.minusYears(10)); // 2093-05-20T00:00

final var dateTime = LocalDateTime.of(2104, 2, 29, 0, 0);
System.out.println(dateTime); // 2104-02-29T00:00
System.out.println(dateTime.minusYears(1)); // 2103-02-28T00:00

static LocalDateTime now ()

デフォルトのタイムゾーンのシステム・クロックから現在の日付/時間を取得します。

final var dateTime = LocalDateTime.now();
System.out.println(dateTime); // 2024-05-18T16:34:31.603367500

static LocalDateTime now (Clock clock)

指定されたクロックから現在の日付/時間を取得します。

// 意図的に５日進めた Clock です。
final var clock = Clock.offset(Clock.systemDefaultZone(), Duration.ofDays(5));

System.out.println(LocalDateTime.now()); // 2024-05-18T16:35:07.450483800
System.out.println(LocalDateTime.now(clock)); // 2024-05-23T16:35:07.451482800

static LocalDateTime now (ZoneId zone)

指定されたタイムゾーンのシステム・クロックから現在の日付/時間を取得します。

final var zone1 = ZoneId.systemDefault();
System.out.println(zone1); // Asia/Tokyo

final var zone2 = ZoneId.of("America/Los_Angeles");
System.out.println(zone2); // America/Los_Angeles

System.out.println(LocalDateTime.now(zone1)); // 2024-05-18T16:36:51.435274500
System.out.println(LocalDateTime.now(zone2)); // 2024-05-18T00:36:51.435274500

static LocalDateTime of (int year, int month, int dayOfMonth, int hour, int minute)

秒およびナノ秒をゼロに設定して、年、月、日、時、および分からLocalDateTimeのインスタンスを取得します。

System.out.println(LocalDateTime.of(2100, 4, 14, 13, 30)); // 2100-04-14T13:30
System.out.println(LocalDateTime.of(1900, 2, 28, 0, 0)); // 1900-02-28T00:00
System.out.println(LocalDateTime.of(-999, 12, 1, 23, 59)); // -0999-12-01T23:59

static LocalDateTime of (int year, int month, int dayOfMonth, int hour, int minute, int second)

ナノ秒をゼロに設定して、年、月、日、時、分、および秒からLocalDateTimeのインスタンスを取得します。

System.out.println(LocalDateTime.of(2100, 4, 14, 13, 30, 10)); // 2100-04-14T13:30:10
System.out.println(LocalDateTime.of(1900, 2, 28, 0, 0, 0)); // 1900-02-28T00:00
System.out.println(LocalDateTime.of(-999, 12, 1, 23, 59, 59)); // -0999-12-01T23:59:59

static LocalDateTime of (int year, int month, int dayOfMonth, int hour, int minute, int second, int nanoOfSecond)

年、月、日、時、分、秒、およびナノ秒からLocalDateTimeのインスタンスを取得します。

final var dateTime1 = LocalDateTime.of(2100, 4, 14, 13, 30, 10, 123);
System.out.println(dateTime1); // 2100-04-14T13:30:10.000000123

final var dateTime2 = LocalDateTime.of(1900, 2, 28, 0, 0, 0, 0);
System.out.println(dateTime2); // 1900-02-28T00:00

final var dateTime3 = LocalDateTime.of(-999, 12, 1, 23, 59, 59, 999999999);
System.out.println(dateTime3); // -0999-12-01T23:59:59.999999999

static LocalDateTime of (int year, Month month, int dayOfMonth, int hour, int minute)

秒およびナノ秒をゼロに設定して、年、月、日、時、および分からLocalDateTimeのインスタンスを取得します。

final var dateTime1 = LocalDateTime.of(2100, Month.APRIL, 14, 13, 30);
System.out.println(dateTime1); // 2100-04-14T13:30

final var dateTime2 = LocalDateTime.of(1900, Month.FEBRUARY, 28, 0, 0);
System.out.println(dateTime2); // 1900-02-28T00:00

final var dateTime3 = LocalDateTime.of(-999, Month.DECEMBER, 1, 23, 59);
System.out.println(dateTime3); // -0999-12-01T23:59

static LocalDateTime of (int year, Month month, int dayOfMonth, int hour, int minute, int second)

ナノ秒をゼロに設定して、年、月、日、時、分、および秒からLocalDateTimeのインスタンスを取得します。

final var dateTime1 = LocalDateTime.of(2100, Month.APRIL, 14, 13, 30, 10);
System.out.println(dateTime1); // 2100-04-14T13:30:10

final var dateTime2 = LocalDateTime.of(1900, Month.FEBRUARY, 28, 0, 0, 0);
System.out.println(dateTime2); // 1900-02-28T00:00

final var dateTime3 = LocalDateTime.of(-999, Month.DECEMBER, 1, 23, 59, 59);
System.out.println(dateTime3); // -0999-12-01T23:59:59

static LocalDateTime of (int year, Month month, int dayOfMonth, int hour, int minute, int second, int nanoOfSecond)

年、月、日、時、分、秒、およびナノ秒からLocalDateTimeのインスタンスを取得します。

final var dateTime1 = LocalDateTime.of(2100, Month.APRIL, 14, 13, 30, 10, 123);
System.out.println(dateTime1); // 2100-04-14T13:30:10.000000123

final var dateTime2 = LocalDateTime.of(1900, Month.FEBRUARY, 28, 0, 0, 0, 0);
System.out.println(dateTime2); // 1900-02-28T00:00

final var dateTime3 = LocalDateTime.of(-999, Month.DECEMBER, 1, 23, 59, 59, 999999999);
System.out.println(dateTime3); // -0999-12-01T23:59:59.999999999

static LocalDateTime of (LocalDate date, LocalTime time)

日付と時間からLocalDateTimeのインスタンスを取得します。

final var date = LocalDate.of(2100, Month.APRIL, 14);
System.out.println(date); // 2100-04-14

final var time = LocalTime.of(13, 30, 10);
System.out.println(time); // 13:30:10

System.out.println(LocalDateTime.of(date, time)); // 2100-04-14T13:30:10

final var date = LocalDate.of(1900, Month.FEBRUARY, 28);
System.out.println(date); // 1900-02-28

System.out.println(LocalDateTime.of(date, LocalTime.MIN)); // 1900-02-28T00:00

static LocalDateTime ofEpochSecond (long epochSecond, int nanoOfSecond, ZoneOffset offset)

エポック(1970-01-01T00:00:00Z)からの秒数を使用して、LocalDateTimeのインスタンスを取得します。

final var epochSecond = 4102444800L;
System.out.println(Instant.ofEpochSecond(epochSecond)); // 2100-01-01T00:00:00Z

final var dateTime1 = LocalDateTime.ofEpochSecond(epochSecond, 0, ZoneOffset.UTC);
System.out.println(dateTime1); // 2100-01-01T00:00

final var dateTime2 = LocalDateTime.ofEpochSecond(epochSecond, 0, ZoneOffset.ofHours(-9));
System.out.println(dateTime2); // 2099-12-31T15:00

final var dateTime3 = LocalDateTime.ofEpochSecond(epochSecond, 123, ZoneOffset.UTC);
System.out.println(dateTime3); // 2100-01-01T00:00:00.000000123

static LocalDateTime ofInstant (Instant instant, ZoneId zone)

InstantおよびゾーンIDからLocalDateTimeのインスタンスを取得します。

final var instant = Instant.ofEpochSecond(4102444800L);
System.out.println(instant); // 2100-01-01T00:00:00Z

final var dateTime1 = LocalDateTime.ofInstant(instant, ZoneOffset.UTC);
System.out.println(dateTime1); // 2100-01-01T00:00

final var zoneId = ZoneId.systemDefault();
System.out.println(zoneId); // Asia/Tokyo

final var dateTime2 = LocalDateTime.ofInstant(instant, zoneId);
System.out.println(dateTime2); // 2100-01-01T09:00

static LocalDateTime parse (CharSequence text)

2007-12-03T10:15:30などのテキスト文字列からLocalDateTimeのインスタンスを取得します。

final var ret1 = LocalDateTime.parse("2100-04-14T00:00");
System.out.println(ret1); // 2100-04-14T00:00

final var ret2 = LocalDateTime.parse("2100-04-14T13:30:45");
System.out.println(ret2); // 2100-04-14T13:30:45

final var ret3 = LocalDateTime.parse("2100-04-14T13:30:45.123456789");
System.out.println(ret3); // 2100-04-14T13:30:45.123456789

try {
    final var ret = LocalDateTime.parse("2100/04/14 00:00");
} catch (DateTimeParseException e) {
    System.out.println("DateTimeParseException! : " + e.getMessage());
}

// 結果
// ↓
//DateTimeParseException! : Text '2100/04/14 00:00' could not be parsed at index 4

static LocalDateTime parse (CharSequence text, DateTimeFormatter formatter)

特定のフォーマッタを使用して、テキスト文字列からLocalDateTimeのインスタンスを取得します。

final var ret1 = LocalDateTime.parse(
        "2100-04-14T12:30:45", DateTimeFormatter.ISO_LOCAL_DATE_TIME);
System.out.println(ret1); // 2100-04-14T12:30:45

final var ret2 = LocalDateTime.parse(
        "2100年4月14日12時30分45秒", DateTimeFormatter.ofPattern("y年M月d日H時m分s秒"));
System.out.println(ret2); // 2100-04-14T12:30:45

System.out.println(Locale.getDefault().toLanguageTag()); // ja-JP

final var ret1 = LocalDateTime.parse(
        "2100/04/14 12:30:45",
        DateTimeFormatter.ofLocalizedDateTime(FormatStyle.MEDIUM));
System.out.println(ret1); // 2100-04-14T12:30:45

final var ret2 = LocalDateTime.parse(
        "2100/04/14 12:30",
        DateTimeFormatter.ofLocalizedDateTime(FormatStyle.SHORT));
System.out.println(ret2); // 2100-04-14T12:30

LocalDateTime plus (long amountToAdd, TemporalUnit unit)

指定された量を加算した、この日付/時間のコピーを返します。

final var dateTime = LocalDateTime.of(2100, 4, 13, 0, 0);
System.out.println(dateTime); // 2100-04-13T00:00

final var ret1 = dateTime.plus(1, ChronoUnit.YEARS);
System.out.println(ret1); // 2101-04-13T00:00

final var ret2 = dateTime.plus(2, ChronoUnit.MONTHS);
System.out.println(ret2); // 2100-06-13T00:00

final var ret3 = dateTime.plus(3, ChronoUnit.DAYS);
System.out.println(ret3); // 2100-04-16T00:00

final var dateTime = LocalDateTime.of(2100, 1, 1, 10, 20, 30, 123);
System.out.println(dateTime); // 2100-01-01T10:20:30.000000123

final var ret1 = dateTime.plus(1, ChronoUnit.HOURS);
System.out.println(ret1); // 2100-01-01T11:20:30.000000123

final var ret2 = dateTime.plus(2, ChronoUnit.MINUTES);
System.out.println(ret2); // 2100-01-01T10:22:30.000000123

final var ret3 = dateTime.plus(3, ChronoUnit.SECONDS);
System.out.println(ret3); // 2100-01-01T10:20:33.000000123

final var ret4 = dateTime.plus(4, ChronoUnit.NANOS);
System.out.println(ret4); // 2100-01-01T10:20:30.000000127

final var dateTime = LocalDateTime.of(2100, 12, 31, 23, 0);
System.out.println(dateTime); // 2100-12-31T23:00

final var ret1 = dateTime.plus(1, ChronoUnit.HOURS);
System.out.println(ret1); // 2101-01-01T00:00

final var ret2 = dateTime.plus(366, ChronoUnit.DAYS);
System.out.println(ret2); // 2102-01-01T23:00

final var ret3 = dateTime.plus(3000, ChronoUnit.YEARS);
System.out.println(ret3); // 5100-12-31T23:00

LocalDateTime plus (TemporalAmount amountToAdd)

指定された量を加算した、この日付/時間のコピーを返します。

final var dateTime = LocalDateTime.of(2100, 4, 13, 0, 0);
System.out.println(dateTime); // 2100-04-13T00:00

final var ret1 = dateTime.plus(Period.ofYears(1));
System.out.println(ret1); // 2101-04-13T00:00

final var ret2 = dateTime.plus(Period.ofMonths(2));
System.out.println(ret2); // 2100-06-13T00:00

final var ret3 = dateTime.plus(Period.ofDays(3));
System.out.println(ret3); // 2100-04-16T00:00

final var dateTime = LocalDateTime.of(2100, 1, 1, 10, 20, 30, 123);
System.out.println(dateTime); // 2100-01-01T10:20:30.000000123

final var ret1 = dateTime.plus(Duration.ofHours(1));
System.out.println(ret1); // 2100-01-01T11:20:30.000000123

final var ret2 = dateTime.plus(Duration.ofMinutes(2));
System.out.println(ret2); // 2100-01-01T10:22:30.000000123

final var ret3 = dateTime.plus(Duration.ofSeconds(3));
System.out.println(ret3); // 2100-01-01T10:20:33.000000123

final var ret4 = dateTime.plus(Duration.ofNanos(4));
System.out.println(ret4); // 2100-01-01T10:20:30.000000127

final var dateTime = LocalDateTime.of(2100, 12, 31, 23, 0);
System.out.println(dateTime); // 2100-12-31T23:00

final var ret1 = dateTime.plus(Duration.ofHours(1));
System.out.println(ret1); // 2101-01-01T00:00

final var ret2 = dateTime.plus(Period.ofDays(366));
System.out.println(ret2); // 2102-01-01T23:00

final var ret3 = dateTime.plus(Period.ofYears(3000));
System.out.println(ret3); // 5100-12-31T23:00

LocalDateTime plusDays (long days)

指定された日数を加算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 5, 20, 0, 0);
System.out.println(dateTime); // 2100-05-20T00:00

System.out.println(dateTime.plusDays(1)); // 2100-05-21T00:00
System.out.println(dateTime.plusDays(2)); // 2100-05-22T00:00
System.out.println(dateTime.plusDays(12)); // 2100-06-01T00:00
System.out.println(dateTime.plusDays(365)); // 2101-05-20T00:00

final var dateTime = LocalDateTime.of(2099, 12, 31, 0, 0);
System.out.println(dateTime); // 2099-12-31T00:00

System.out.println(dateTime.plusDays(1)); // 2100-01-01T00:00

LocalDateTime plusHours (long hours)

指定された時間数を加算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 0);
System.out.println(dateTime); // 2100-01-01T13:00

System.out.println(dateTime.plusHours(1)); // 2100-01-01T14:00
System.out.println(dateTime.plusHours(2)); // 2100-01-01T15:00
System.out.println(dateTime.plusHours(11)); // 2100-01-02T00:00
System.out.println(dateTime.plusHours(12)); // 2100-01-02T01:00

LocalDateTime plusMinutes (long minutes)

指定された分数を加算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30);
System.out.println(dateTime); // 2100-01-01T13:30

System.out.println(dateTime.plusMinutes(1)); // 2100-01-01T13:31
System.out.println(dateTime.plusMinutes(2)); // 2100-01-01T13:32
System.out.println(dateTime.plusMinutes(30)); // 2100-01-01T14:00
System.out.println(dateTime.plusMinutes(31)); // 2100-01-01T14:01
System.out.println(dateTime.plusMinutes(60 * 24)); // 2100-01-02T13:30
System.out.println(dateTime.plusMinutes(60 * 24 * 365)); // 2101-01-01T13:30

LocalDateTime plusMonths (long months)

指定された月数を加算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 5, 20, 0, 0);
System.out.println(dateTime); // 2100-05-20T00:00

System.out.println(dateTime.plusMonths(1)); // 2100-06-20T00:00
System.out.println(dateTime.plusMonths(2)); // 2100-07-20T00:00
System.out.println(dateTime.plusMonths(12)); // 2101-05-20T00:00

final var dateTime = LocalDateTime.of(2101, 3, 31, 0, 0);
System.out.println(dateTime); // 2101-03-31T00:00

System.out.println(dateTime.plusMonths(1)); // 2101-04-30T00:00

LocalDateTime plusNanos (long nanos)

指定されたナノ秒数を加算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30, 15, 123);
System.out.println(dateTime); // 2100-01-01T13:30:15.000000123

System.out.println(dateTime.plusNanos(1)); // 2100-01-01T13:30:15.000000124
System.out.println(dateTime.plusNanos(2)); // 2100-01-01T13:30:15.000000125

final var ret1 = dateTime.plusNanos(1000000000L - 124);
System.out.println(ret1); // 2100-01-01T13:30:15.999999999

final var ret2 = dateTime.plusNanos(1000000000L - 123);
System.out.println(ret2); // 2100-01-01T13:30:16

LocalDateTime plusSeconds (long seconds)

指定された秒数を加算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 13, 30, 15);
System.out.println(dateTime); // 2100-01-01T13:30:15

System.out.println(dateTime.plusSeconds(1)); // 2100-01-01T13:30:16
System.out.println(dateTime.plusSeconds(2)); // 2100-01-01T13:30:17
System.out.println(dateTime.plusSeconds(45)); // 2100-01-01T13:31
System.out.println(dateTime.plusSeconds(46)); // 2100-01-01T13:31:01
System.out.println(dateTime.plusSeconds(60 + 45)); // 2100-01-01T13:32
System.out.println(dateTime.plusSeconds(60 * 60)); // 2100-01-01T14:30:15
System.out.println(dateTime.plusSeconds(60 * 60 * 24)); // 2100-01-02T13:30:15

LocalDateTime plusWeeks (long weeks)

指定された週数を加算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 5, 20, 0, 0);
System.out.println(dateTime); // 2100-05-20T00:00

System.out.println(dateTime.plusWeeks(1)); // 2100-05-27T00:00
System.out.println(dateTime.plusWeeks(2)); // 2100-06-03T00:00
System.out.println(dateTime.plusWeeks(20)); // 2100-10-07T00:00
System.out.println(dateTime.plusWeeks(100)); // 2102-04-20T00:00

final var dateTime = LocalDateTime.of(2100, 12, 31, 0, 0);
System.out.println(dateTime); // 2100-12-31T00:00

System.out.println(dateTime.plusWeeks(1)); // 2101-01-07T00:00

LocalDateTime plusYears (long years)

指定された年数を加算して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2103, 5, 20, 0, 0);
System.out.println(dateTime); // 2103-05-20T00:00

System.out.println(dateTime.plusYears(1)); // 2104-05-20T00:00
System.out.println(dateTime.plusYears(2)); // 2105-05-20T00:00
System.out.println(dateTime.plusYears(10)); // 2113-05-20T00:00

final var dateTime = LocalDateTime.of(2104, 2, 29, 0, 0);
System.out.println(dateTime); // 2104-02-29T00:00

System.out.println(dateTime.plusYears(1)); // 2105-02-28T00:00

<R> R query (TemporalQuery<R> query)

指定された問合せを使用してこの日付/時間を問い合わせます。

final var dateTime = LocalDateTime.of(2100, 4, 14, 12, 30);
System.out.println(dateTime); // 2100-04-14T12:30

System.out.println(dateTime.query(TemporalQueries.localDate())); // 2100-04-14
System.out.println(dateTime.query(TemporalQueries.localTime())); // 12:30
System.out.println(dateTime.query(TemporalQueries.precision())); // Nanos

ValueRange range (TemporalField field)

指定されたフィールドの有効な値の範囲を取得します。

final var dateTime = LocalDateTime.of(2100, 4, 14, 0, 0);
System.out.println(dateTime); // 2100-04-14T00:00
System.out.println(dateTime.range(ChronoField.YEAR)); // -999999999 - 999999999
System.out.println(dateTime.range(ChronoField.MONTH_OF_YEAR)); // 1 - 12
System.out.println(dateTime.range(ChronoField.DAY_OF_MONTH)); // 1 - 30

System.out.println(dateTime.range(ChronoField.HOUR_OF_DAY)); // 0 - 23
System.out.println(dateTime.range(ChronoField.MINUTE_OF_HOUR)); // 0 - 59
System.out.println(dateTime.range(ChronoField.SECOND_OF_MINUTE)); // 0 - 59
System.out.println(dateTime.range(ChronoField.NANO_OF_SECOND)); // 0 - 999999999

final var dateTime1 = LocalDateTime.of(2103, 2, 1, 0, 0);
System.out.println(dateTime1); // 2103-02-01T00:00
System.out.println(dateTime1.range(ChronoField.DAY_OF_MONTH)); // 1 - 28

final var dateTime2 = LocalDateTime.of(2104, 2, 1, 0, 0);
System.out.println(dateTime2); // 2104-02-01T00:00
System.out.println(dateTime2.range(ChronoField.DAY_OF_MONTH)); // 1 - 29

LocalDate toLocalDate ()

この日付/時間のLocalDate部分を取得します。

final var dateTime = LocalDateTime.of(2100, 4, 14, 12, 30, 45);
System.out.println(dateTime); // 2100-04-14T12:30:45
System.out.println(dateTime.toLocalDate()); // 2100-04-14

final var dateTime = LocalDateTime.of(1900, 1, 1, 0, 0);
System.out.println(dateTime); // 1900-01-01T00:00
System.out.println(dateTime.toLocalDate()); // 1900-01-01

final var dateTime = LocalDateTime.MAX;
System.out.println(dateTime); // +999999999-12-31T23:59:59.999999999
System.out.println(dateTime.toLocalDate()); // +999999999-12-31

final var dateTime = LocalDateTime.MIN;
System.out.println(dateTime); // -999999999-01-01T00:00
System.out.println(dateTime.toLocalDate()); // -999999999-01-01

LocalTime toLocalTime ()

この日付/時間のLocalTime部分を取得します。

final var dateTime = LocalDateTime.of(2100, 4, 14, 12, 30, 45);
System.out.println(dateTime); // 2100-04-14T12:30:45
System.out.println(dateTime.toLocalTime()); // 12:30:45

final var dateTime = LocalDateTime.of(1900, 1, 1, 0, 0);
System.out.println(dateTime); // 1900-01-01T00:00
System.out.println(dateTime.toLocalTime()); // 00:00

final var dateTime = LocalDateTime.MAX;
System.out.println(dateTime); // +999999999-12-31T23:59:59.999999999
System.out.println(dateTime.toLocalTime()); // 23:59:59.999999999

final var dateTime = LocalDateTime.MIN;
System.out.println(dateTime); // -999999999-01-01T00:00
System.out.println(dateTime.toLocalTime()); // 00:00

String toString ()

この日付/時間をStringとして出力します(2007-12-03T10:15:30など)。

final var dateTime = LocalDateTime.of(2100, 4, 14, 12, 30, 45);
final var str = dateTime.toString();
System.out.println(str); // 2100-04-14T12:30:45

final var dateTime = LocalDateTime.of(2100, 12, 1, 23, 59);
final var str = dateTime.toString();
System.out.println(str); // 2100-12-01T23:59

final var dateTime1 = LocalDateTime.of(1900, 1, 1, 0, 0, 0, 123000000);
final var str1 = dateTime1.toString();
System.out.println(str1); // 1900-01-01T00:00:00.123

final var dateTime2 = LocalDateTime.of(1900, 1, 1, 0, 0, 0, 123000);
final var str2 = dateTime2.toString();
System.out.println(str2); // 1900-01-01T00:00:00.000123

final var dateTime3 = LocalDateTime.of(1900, 1, 1, 0, 0, 0, 123);
final var str3 = dateTime3.toString();
System.out.println(str3); // 1900-01-01T00:00:00.000000123

final var dateTime = LocalDateTime.MAX;
final var str = dateTime.toString();
System.out.println(str); // +999999999-12-31T23:59:59.999999999

final var dateTime = LocalDateTime.MIN;
final var str = dateTime.toString();
System.out.println(str); // -999999999-01-01T00:00

LocalDateTime truncatedTo (TemporalUnit unit)

時間が切り捨てられた、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 4, 14, 12, 30, 15, 123456789);
System.out.println(dateTime); // 2100-04-14T12:30:15.123456789

System.out.println(dateTime.truncatedTo(ChronoUnit.DAYS)); // 2100-04-14T00:00

System.out.println(dateTime.truncatedTo(ChronoUnit.HOURS)); // 2100-04-14T12:00
System.out.println(dateTime.truncatedTo(ChronoUnit.MINUTES)); // 2100-04-14T12:30
System.out.println(dateTime.truncatedTo(ChronoUnit.SECONDS)); // 2100-04-14T12:30:15

final var ret = dateTime.truncatedTo(ChronoUnit.NANOS);
System.out.println(ret); // 2100-04-14T12:30:15.123456789

long until (Temporal endExclusive, TemporalUnit unit)

もう一方の日付/時間までの時間量を指定された単位で計算します。

final var dateTime1 = LocalDateTime.of(2100, 1, 1, 0, 0);
final var dateTime2 = LocalDateTime.of(2101, 2, 2, 0, 0);
System.out.println(dateTime1); // 2100-01-01T00:00
System.out.println(dateTime2); // 2101-02-02T00:00

System.out.println(dateTime1.until(dateTime2, ChronoUnit.YEARS)); // 1
System.out.println(dateTime1.until(dateTime2, ChronoUnit.MONTHS)); // 13
System.out.println(dateTime1.until(dateTime2, ChronoUnit.DAYS)); // 397
System.out.println(dateTime1.until(dateTime2, ChronoUnit.HOURS)); // 9528
System.out.println(dateTime1.until(dateTime2, ChronoUnit.MINUTES)); // 571680
System.out.println(dateTime1.until(dateTime2, ChronoUnit.SECONDS)); // 34300800
System.out.println(dateTime1.until(dateTime2, ChronoUnit.NANOS)); // 34300800000000000

final var dateTime1 = LocalDateTime.of(2100, 1, 1, 1, 2);
final var dateTime2 = LocalDateTime.of(2100, 1, 1, 3, 32, 15, 123);
System.out.println(dateTime1); // 2100-01-01T01:02
System.out.println(dateTime2); // 2100-01-01T03:32:15.000000123

System.out.println(dateTime1.until(dateTime2, ChronoUnit.YEARS)); // 0
System.out.println(dateTime1.until(dateTime2, ChronoUnit.MONTHS)); // 0
System.out.println(dateTime1.until(dateTime2, ChronoUnit.DAYS)); // 0
System.out.println(dateTime1.until(dateTime2, ChronoUnit.HOURS)); // 2
System.out.println(dateTime1.until(dateTime2, ChronoUnit.MINUTES)); // 150
System.out.println(dateTime1.until(dateTime2, ChronoUnit.SECONDS)); // 9015
System.out.println(dateTime1.until(dateTime2, ChronoUnit.NANOS)); // 9015000000123

final var dateTime1 = LocalDateTime.of(1900, 8, 14, 0, 0);
final var dateTime2 = LocalDateTime.of(1900, 6, 15, 0, 0);
System.out.println(dateTime1); // 1900-08-14T00:00
System.out.println(dateTime2); // 1900-06-15T00:00

System.out.println(dateTime1.until(dateTime2, ChronoUnit.YEARS)); // 0
System.out.println(dateTime1.until(dateTime2, ChronoUnit.MONTHS)); // -1
System.out.println(dateTime1.until(dateTime2, ChronoUnit.DAYS)); // -60
System.out.println(dateTime1.until(dateTime2, ChronoUnit.HOURS)); // -1440
System.out.println(dateTime1.until(dateTime2, ChronoUnit.MINUTES)); // -86400
System.out.println(dateTime1.until(dateTime2, ChronoUnit.SECONDS)); // -5184000
System.out.println(dateTime1.until(dateTime2, ChronoUnit.NANOS)); // -5184000000000000

LocalDateTime with (TemporalAdjuster adjuster)

この日付/時間の調整済のコピーを返します。

final var dateTime = LocalDateTime.of(2100, 3, 15, 0, 0);
System.out.println(dateTime); // 2100-03-15T00:00

final var ret1 = dateTime.with(TemporalAdjusters.firstDayOfMonth());
System.out.println(ret1); // 2100-03-01T00:00

final var ret2 = dateTime.with(TemporalAdjusters.lastDayOfMonth());
System.out.println(ret2); // 2100-03-31T00:00

final var dateTime = LocalDateTime.of(2100, 4, 14, 12, 30);
System.out.println(dateTime); // 2100-04-14T12:30

System.out.println(dateTime.with(Year.of(1999))); // 1999-04-14T12:30
System.out.println(dateTime.with(Month.JANUARY)); // 2100-01-14T12:30
System.out.println(dateTime.with(LocalTime.MAX)); // 2100-04-14T23:59:59.999999999
System.out.println(dateTime.with(LocalDate.MIN)); // -999999999-01-01T12:30

LocalDateTime with (TemporalField field, long newValue)

指定されたフィールドを新しい値に設定して、この日付/時間のコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 2, 12, 30, 45, 123);
System.out.println(dateTime); // 2100-01-02T12:30:45.000000123

final var ret1 = dateTime.with(ChronoField.YEAR, 1999);
System.out.println(ret1); // 1999-01-02T12:30:45.000000123

final var ret2 = dateTime.with(ChronoField.MONTH_OF_YEAR, 12);
System.out.println(ret2); // 2100-12-02T12:30:45.000000123

final var ret3 = dateTime.with(ChronoField.DAY_OF_MONTH, 30);
System.out.println(ret3); // 2100-01-30T12:30:45.000000123

final var ret4 = dateTime.with(ChronoField.HOUR_OF_DAY, 23);
System.out.println(ret4); // 2100-01-02T23:30:45.000000123

final var ret5 = dateTime.with(ChronoField.MINUTE_OF_HOUR, 59);
System.out.println(ret5); // 2100-01-02T12:59:45.000000123

final var ret6 = dateTime.with(ChronoField.SECOND_OF_MINUTE, 0);
System.out.println(ret6); // 2100-01-02T12:30:00.000000123

final var ret7 = dateTime.with(ChronoField.NANO_OF_SECOND, 456);
System.out.println(ret7); // 2100-01-02T12:30:45.000000456

LocalDateTime withDayOfMonth (int dayOfMonth)

「月の日」を変更して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 4, 8, 0, 0);
System.out.println(dateTime); // 2100-04-08T00:00

System.out.println(dateTime.withDayOfMonth(1)); // 2100-04-01T00:00
System.out.println(dateTime.withDayOfMonth(2)); // 2100-04-02T00:00
System.out.println(dateTime.withDayOfMonth(29)); // 2100-04-29T00:00
System.out.println(dateTime.withDayOfMonth(30)); // 2100-04-30T00:00

LocalDateTime withDayOfYear (int dayOfYear)

「年の日」を変更して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 4, 8, 12, 30);
System.out.println(dateTime); // 2100-04-08T12:30

System.out.println(dateTime.withDayOfYear(1)); // 2100-01-01T12:30
System.out.println(dateTime.withDayOfYear(2)); // 2100-01-02T12:30
System.out.println(dateTime.withDayOfYear(30)); // 2100-01-30T12:30
System.out.println(dateTime.withDayOfYear(31)); // 2100-01-31T12:30
System.out.println(dateTime.withDayOfYear(32)); // 2100-02-01T12:30
System.out.println(dateTime.withDayOfYear(33)); // 2100-02-02T12:30

System.out.println(dateTime.withDayOfYear(365)); // 2100-12-31T12:30

LocalDateTime withHour (int hour)

時の値を変更して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 12, 30);
System.out.println(dateTime); // 2100-01-01T12:30

System.out.println(dateTime.withHour(0)); // 2100-01-01T00:30
System.out.println(dateTime.withHour(23)); // 2100-01-01T23:30

LocalDateTime withMinute (int minute)

分の値を変更して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 12, 30);
System.out.println(dateTime); // 2100-01-01T12:30

System.out.println(dateTime.withMinute(0)); // 2100-01-01T12:00
System.out.println(dateTime.withMinute(59)); // 2100-01-01T12:59

LocalDateTime withMonth (int month)

月を変更して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 4, 8, 12, 30);
System.out.println(dateTime); // 2100-04-08T12:30

System.out.println(dateTime.withMonth(1)); // 2100-01-08T12:30
System.out.println(dateTime.withMonth(2)); // 2100-02-08T12:30
System.out.println(dateTime.withMonth(11)); // 2100-11-08T12:30
System.out.println(dateTime.withMonth(12)); // 2100-12-08T12:30

LocalDateTime withNano (int nanoOfSecond)

ナノ秒の値を変更して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 0, 0, 0, 123);
System.out.println(dateTime); // 2100-01-01T00:00:00.000000123

System.out.println(dateTime.withNano(0)); // 2100-01-01T00:00
System.out.println(dateTime.withNano(999999999)); // 2100-01-01T00:00:00.999999999

LocalDateTime withSecond (int second)

秒の値を変更して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 1, 1, 12, 30, 45);
System.out.println(dateTime); // 2100-01-01T12:30:45

System.out.println(dateTime.withSecond(0)); // 2100-01-01T12:30
System.out.println(dateTime.withSecond(1)); // 2100-01-01T12:30:01
System.out.println(dateTime.withSecond(59)); // 2100-01-01T12:30:59

LocalDateTime withYear (int year)

年を変更して、このLocalDateTimeのコピーを返します。

final var dateTime = LocalDateTime.of(2100, 4, 8, 12, 30);
System.out.println(dateTime); // 2100-04-08T12:30

System.out.println(dateTime.withYear(1999)); // 1999-04-08T12:30
System.out.println(dateTime.withYear(-999)); // -0999-04-08T12:30
System.out.println(dateTime.withYear(2500)); // 2500-04-08T12:30

ChronoLocalDateTimeで宣言されたメソッド

getChronology, toEpochSecond, toInstant

「Java API 使用例 : ChronoLocalDateTime」をご参照ください。

API 使用例