DayOfWeek (Java SE 23 & JDK 23)
Description: declaration: module: java.base, package: java.time, enum: DayOfWeek
Keywords: java.time.DayOfWeek class

# Enum Class DayOfWeek

java.lang.Object
java.lang.Enum<DayOfWeek>
java.time.DayOfWeek

All Implemented Interfaces:
  `Serializable`, `Comparable<DayOfWeek>`, `Constable`, `TemporalAccessor`, `TemporalAdjuster`

public enum DayOfWeek extends Enum<DayOfWeek> implements TemporalAccessor, TemporalAdjuster
A day-of-week, such as 'Tuesday'.

`DayOfWeek` is an enum representing the 7 days of the week - Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday.

In addition to the textual enum name, each day-of-week has an `int` value. The `int` value follows the ISO-8601 standard, from 1 (Monday) to 7 (Sunday). It is recommended that applications use the enum rather than the `int` value to ensure code clarity.

This enum provides access to the localized textual form of the day-of-week. Some locales also assign different numeric values to the days, declaring Sunday to have the value 1, however this class provides no support for this. See `WeekFields` for localized week-numbering.

Do not use `ordinal()` to obtain the numeric representation of `DayOfWeek`. Use `getValue()` instead.

This enum represents a common concept that is found in many calendar systems. As such, this enum may be used by any calendar system that has the day-of-week concept defined exactly equivalent to the ISO calendar system.

Implementation Requirements:
  This is an immutable and thread-safe enum.
Since:
  1.8

- ## Nested Class Summary

  ### Nested classes/interfaces declared in class java.lang.Enum

  `Enum.EnumDesc<E extends Enum<E>>`

- ## Enum Constant Summary

  Enum Constants
  Enum Constant
  Description
  `FRIDAY`
  The singleton instance for the day-of-week of Friday.
  `MONDAY`
  The singleton instance for the day-of-week of Monday.
  `SATURDAY`
  The singleton instance for the day-of-week of Saturday.
  `SUNDAY`
  The singleton instance for the day-of-week of Sunday.
  `THURSDAY`
  The singleton instance for the day-of-week of Thursday.
  `TUESDAY`
  The singleton instance for the day-of-week of Tuesday.
  `WEDNESDAY`
  The singleton instance for the day-of-week of Wednesday.

- ## Method Summary

  Modifier and Type
  Method
  Description
  `Temporal`
  `adjustInto(Temporal temporal)`
  Adjusts the specified temporal object to have this day-of-week.
  `static DayOfWeek`
  `from(TemporalAccessor temporal)`
  Obtains an instance of `DayOfWeek` from a temporal object.
  `int`
  `get(TemporalField field)`
  Gets the value of the specified field from this day-of-week as an `int`.
  `String`
  `getDisplayName(TextStyle style, Locale locale)`
  Gets the textual representation, such as 'Mon' or 'Friday'.
  `long`
  `getLong(TemporalField field)`
  Gets the value of the specified field from this day-of-week as a `long`.
  `int`
  `getValue()`
  Gets the day-of-week `int` value.
  `boolean`
  `isSupported(TemporalField field)`
  Checks if the specified field is supported.
  `DayOfWeek`
  `minus(long days)`
  Returns the day-of-week that is the specified number of days before this one.
  `static DayOfWeek`
  `of(int dayOfWeek)`
  Obtains an instance of `DayOfWeek` from an `int` value.
  `DayOfWeek`
  `plus(long days)`
  Returns the day-of-week that is the specified number of days after this one.
  `<R> R`
  `query(TemporalQuery<R> query)`
  Queries this day-of-week using the specified query.
  `ValueRange`
  `range(TemporalField field)`
  Gets the range of valid values for the specified field.
  `static DayOfWeek`
  `valueOf(String name)`
  Returns the enum constant of this class with the specified name.
  `static DayOfWeek[]`
  `values()`
  Returns an array containing the constants of this enum class, in the order they are declared.

  ### Methods declared in class java.lang.Enum

  `clone, compareTo, describeConstable, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf`

  ### Methods declared in class java.lang.Object

  `getClass, notify, notifyAll, wait, wait, wait`

- ## Enum Constant Details

  - ### MONDAY

    public static final DayOfWeek MONDAY
    The singleton instance for the day-of-week of Monday. This has the numeric value of `1`.

  - ### TUESDAY

    public static final DayOfWeek TUESDAY
    The singleton instance for the day-of-week of Tuesday. This has the numeric value of `2`.

  - ### WEDNESDAY

    public static final DayOfWeek WEDNESDAY
    The singleton instance for the day-of-week of Wednesday. This has the numeric value of `3`.

  - ### THURSDAY

    public static final DayOfWeek THURSDAY
    The singleton instance for the day-of-week of Thursday. This has the numeric value of `4`.

  - ### FRIDAY

    public static final DayOfWeek FRIDAY
    The singleton instance for the day-of-week of Friday. This has the numeric value of `5`.

  - ### SATURDAY

    public static final DayOfWeek SATURDAY
    The singleton instance for the day-of-week of Saturday. This has the numeric value of `6`.

  - ### SUNDAY

    public static final DayOfWeek SUNDAY
    The singleton instance for the day-of-week of Sunday. This has the numeric value of `7`.

- ## Method Details

  - ### values

    public static DayOfWeek[] values()
    Returns an array containing the constants of this enum class, in the order they are declared.
    Returns:
      an array containing the constants of this enum class, in the order they are declared

  - ### valueOf

    public static DayOfWeek valueOf(String name)
    Returns the enum constant of this class with the specified name. The string must match exactly an identifier used to declare an enum constant in this class. (Extraneous whitespace characters are not permitted.)
    Parameters:
      `name` - the name of the enum constant to be returned.
    Returns:
      the enum constant with the specified name
    Throws:
      `IllegalArgumentException` - if this enum class has no constant with the specified name
      `NullPointerException` - if the argument is null

  - ### of

    public static DayOfWeek of(int dayOfWeek)
    Obtains an instance of `DayOfWeek` from an `int` value.

    `DayOfWeek` is an enum representing the 7 days of the week. This factory allows the enum to be obtained from the `int` value. The `int` value follows the ISO-8601 standard, from 1 (Monday) to 7 (Sunday).

    Parameters:
      `dayOfWeek` - the day-of-week to represent, from 1 (Monday) to 7 (Sunday)
    Returns:
      the day-of-week singleton, not null
    Throws:
      `DateTimeException` - if the day-of-week is invalid

  - ### from

    public static DayOfWeek from(TemporalAccessor temporal)
    Obtains an instance of `DayOfWeek` from a temporal object.

    This obtains a day-of-week based on the specified temporal. A `TemporalAccessor` represents an arbitrary set of date and time information, which this factory converts to an instance of `DayOfWeek`.

    The conversion extracts the `DAY_OF_WEEK` field.

    This method matches the signature of the functional interface `TemporalQuery` allowing it to be used as a query via method reference, `DayOfWeek::from`.

    Parameters:
      `temporal` - the temporal object to convert, not null
    Returns:
      the day-of-week, not null
    Throws:
      `DateTimeException` - if unable to convert to a `DayOfWeek`

  - ### getValue

    public int getValue()
    Gets the day-of-week `int` value.

    The values are numbered following the ISO-8601 standard, from 1 (Monday) to 7 (Sunday). See `WeekFields.dayOfWeek()` for localized week-numbering.

    Returns:
      the day-of-week, from 1 (Monday) to 7 (Sunday)

  - ### getDisplayName

    public String getDisplayName(TextStyle style, Locale locale)
    Gets the textual representation, such as 'Mon' or 'Friday'.

    This returns the textual name used to identify the day-of-week, suitable for presentation to the user. The parameters control the style of the returned text and the locale.

    If no textual mapping is found then the `numeric value` is returned.

    Parameters:
      `style` - the length of the text required, not null
      `locale` - the locale to use, not null
    Returns:
      the text value of the day-of-week, not null

  - ### isSupported

    public boolean isSupported(TemporalField field)
    Checks if the specified field is supported.

    This checks if this day-of-week can be queried for the specified field. If false, then calling the `range` and `get` methods will throw an exception.

    If the field is `DAY_OF_WEEK` then this method returns true. All other `ChronoField` instances will return false.

    If the field is not a `ChronoField`, then the result of this method is obtained by invoking `TemporalField.isSupportedBy(TemporalAccessor)` passing `this` as the argument. Whether the field is supported is determined by the field.

    Specified by:
      `isSupported` in interface `TemporalAccessor`
    Parameters:
      `field` - the field to check, null returns false
    Returns:
      true if the field is supported on this day-of-week, false if not

  - ### range

    public ValueRange range(TemporalField field)
    Gets the range of valid values for the specified field.

    The range object expresses the minimum and maximum valid values for a field. This day-of-week is used to enhance the accuracy of the returned range. If it is not possible to return the range, because the field is not supported or for some other reason, an exception is thrown.

    If the field is `DAY_OF_WEEK` then the range of the day-of-week, from 1 to 7, will be returned. All other `ChronoField` instances will throw an `UnsupportedTemporalTypeException`.

    If the field is not a `ChronoField`, then the result of this method is obtained by invoking `TemporalField.rangeRefinedBy(TemporalAccessor)` passing `this` as the argument. Whether the range can be obtained is determined by the field.

    Specified by:
      `range` in interface `TemporalAccessor`
    Parameters:
      `field` - the field to query the range for, not null
    Returns:
      the range of valid values for the field, not null
    Throws:
      `DateTimeException` - if the range for the field cannot be obtained
      `UnsupportedTemporalTypeException` - if the field is not supported

  - ### get

    public int get(TemporalField field)
    Gets the value of the specified field from this day-of-week as an `int`.

    This queries this day-of-week for the value of the specified field. The returned value will always be within the valid range of values for the field. If it is not possible to return the value, because the field is not supported or for some other reason, an exception is thrown.

    If the field is `DAY_OF_WEEK` then the value of the day-of-week, from 1 to 7, will be returned. All other `ChronoField` instances will throw an `UnsupportedTemporalTypeException`.

    If the field is not a `ChronoField`, then the result of this method is obtained by invoking `TemporalField.getFrom(TemporalAccessor)` passing `this` as the argument. Whether the value can be obtained, and what the value represents, is determined by the field.

    Specified by:
      `get` in interface `TemporalAccessor`
    Parameters:
      `field` - the field to get, not null
    Returns:
      the value for the field, within the valid range of values
    Throws:
      `DateTimeException` - if a value for the field cannot be obtained or the value is outside the range of valid values for the field
      `UnsupportedTemporalTypeException` - if the field is not supported or the range of values exceeds an `int`
      `ArithmeticException` - if numeric overflow occurs

  - ### getLong

    public long getLong(TemporalField field)
    Gets the value of the specified field from this day-of-week as a `long`.

    This queries this day-of-week for the value of the specified field. If it is not possible to return the value, because the field is not supported or for some other reason, an exception is thrown.

    If the field is `DAY_OF_WEEK` then the value of the day-of-week, from 1 to 7, will be returned. All other `ChronoField` instances will throw an `UnsupportedTemporalTypeException`.

    If the field is not a `ChronoField`, then the result of this method is obtained by invoking `TemporalField.getFrom(TemporalAccessor)` passing `this` as the argument. Whether the value can be obtained, and what the value represents, is determined by the field.

    Specified by:
      `getLong` in interface `TemporalAccessor`
    Parameters:
      `field` - the field to get, not null
    Returns:
      the value for the field
    Throws:
      `DateTimeException` - if a value for the field cannot be obtained
      `UnsupportedTemporalTypeException` - if the field is not supported
      `ArithmeticException` - if numeric overflow occurs

  - ### plus

    public DayOfWeek plus(long days)
    Returns the day-of-week that is the specified number of days after this one.

    The calculation rolls around the end of the week from Sunday to Monday. The specified period may be negative.

    This instance is immutable and unaffected by this method call.

    Parameters:
      `days` - the days to add, positive or negative
    Returns:
      the resulting day-of-week, not null

  - ### minus

    public DayOfWeek minus(long days)
    Returns the day-of-week that is the specified number of days before this one.

    The calculation rolls around the start of the week from Monday to Sunday. The specified period may be negative.

    This instance is immutable and unaffected by this method call.

    Parameters:
      `days` - the days to subtract, positive or negative
    Returns:
      the resulting day-of-week, not null

  - ### query

    public <R> R query(TemporalQuery<R> query)
    Queries this day-of-week using the specified query.

    This queries this day-of-week using the specified query strategy object. The `TemporalQuery` object defines the logic to be used to obtain the result. Read the documentation of the query to understand what the result of this method will be.

    The result of this method is obtained by invoking the `TemporalQuery.queryFrom(TemporalAccessor)` method on the specified query passing `this` as the argument.

    Specified by:
      `query` in interface `TemporalAccessor`
    Type Parameters:
      `R` - the type of the result
    Parameters:
      `query` - the query to invoke, not null
    Returns:
      the query result, null may be returned (defined by the query)
    Throws:
      `DateTimeException` - if unable to query (defined by the query)
      `ArithmeticException` - if numeric overflow occurs (defined by the query)

  - ### adjustInto

    public Temporal adjustInto(Temporal temporal)
    Adjusts the specified temporal object to have this day-of-week.

    This returns a temporal object of the same observable type as the input with the day-of-week changed to be the same as this.

    The adjustment is equivalent to using `Temporal.with(TemporalField, long)` passing `ChronoField.DAY_OF_WEEK` as the field. Note that this adjusts forwards or backwards within a Monday to Sunday week. See `WeekFields.dayOfWeek()` for localized week start days. See `TemporalAdjuster` for other adjusters with more control, such as `next(MONDAY)`.

    In most cases, it is clearer to reverse the calling pattern by using `Temporal.with(TemporalAdjuster)`:

           // these two lines are equivalent, but the second approach is recommended
           temporal = thisDayOfWeek.adjustInto(temporal);
           temporal = temporal.with(thisDayOfWeek);

    For example, given a date that is a Wednesday, the following are output:

           dateOnWed.with(MONDAY);     // two days earlier
           dateOnWed.with(TUESDAY);    // one day earlier
           dateOnWed.with(WEDNESDAY);  // same date
           dateOnWed.with(THURSDAY);   // one day later
           dateOnWed.with(FRIDAY);     // two days later
           dateOnWed.with(SATURDAY);   // three days later
           dateOnWed.with(SUNDAY);     // four days later

    This instance is immutable and unaffected by this method call.

    Specified by:
      `adjustInto` in interface `TemporalAdjuster`
    Parameters:
      `temporal` - the target object to be adjusted, not null
    Returns:
      the adjusted object, not null
    Throws:
      `DateTimeException` - if unable to make the adjustment
      `ArithmeticException` - if numeric overflow occurs