Module java.base

Package java.time

Enum Class Month

java.lang.Object

java.lang.Enum<Month>

java.time.Month

All Implemented Interfaces:

Serializable, Comparable<Month>, Constable, TemporalAccessor, TemporalAdjuster

public enum Month
extends Enum<Month>
implements TemporalAccessor, TemporalAdjuster

A month-of-year, such as 'July'.

Month is an enum representing the 12 months of the year - January, February, March, April, May, June, July, August, September, October, November and December.

In addition to the textual enum name, each month-of-year has an int value. The int value follows normal usage and the ISO-8601 standard, from 1 (January) to 12 (December). It is recommended that applications use the enum rather than the int value to ensure code clarity.

Do not use ordinal() to obtain the numeric representation of Month. 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 month-of-year concept defined exactly equivalent to the ISO-8601 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
APRIL	The singleton instance for the month of April with 30 days.
AUGUST	The singleton instance for the month of August with 31 days.
DECEMBER	The singleton instance for the month of December with 31 days.
FEBRUARY	The singleton instance for the month of February with 28 days, or 29 in a leap year.
JANUARY	The singleton instance for the month of January with 31 days.
JULY	The singleton instance for the month of July with 31 days.
JUNE	The singleton instance for the month of June with 30 days.
MARCH	The singleton instance for the month of March with 31 days.
MAY	The singleton instance for the month of May with 31 days.
NOVEMBER	The singleton instance for the month of November with 30 days.
OCTOBER	The singleton instance for the month of October with 31 days.
SEPTEMBER	The singleton instance for the month of September with 30 days.

Method Summary

Modifier and Type	Method	Description
Temporal	adjustInto(Temporal temporal)	Adjusts the specified temporal object to have this month-of-year.
int	firstDayOfYear(boolean leapYear)	Gets the day-of-year corresponding to the first day of this month.
Month	firstMonthOfQuarter()	Gets the month corresponding to the first month of this quarter.
static Month	from(TemporalAccessor temporal)	Obtains an instance of Month from a temporal object.
int	get(TemporalField field)	Gets the value of the specified field from this month-of-year as an int.
String	getDisplayName(TextStyle style, Locale locale)	Gets the textual representation, such as 'Jan' or 'December'.
long	getLong(TemporalField field)	Gets the value of the specified field from this month-of-year as a long.
int	getValue()	Gets the month-of-year int value.
boolean	isSupported(TemporalField field)	Checks if the specified field is supported.
int	length(boolean leapYear)	Gets the length of this month in days.
int	maxLength()	Gets the maximum length of this month in days.
int	minLength()	Gets the minimum length of this month in days.
Month	minus(long months)	Returns the month-of-year that is the specified number of months before this one.
static Month	of(int month)	Obtains an instance of Month from an int value.
Month	plus(long months)	Returns the month-of-year that is the specified number of months after this one.
<R> R	query(TemporalQuery<R> query)	Queries this month-of-year using the specified query.
ValueRange	range(TemporalField field)	Gets the range of valid values for the specified field.
static Month	valueOf(String name)	Returns the enum constant of this class with the specified name.
static Month[]	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

JANUARY

public static final Month JANUARY

The singleton instance for the month of January with 31 days. This has the numeric value of 1.

FEBRUARY

public static final Month FEBRUARY

The singleton instance for the month of February with 28 days, or 29 in a leap year. This has the numeric value of 2.

MARCH

public static final Month MARCH

The singleton instance for the month of March with 31 days. This has the numeric value of 3.

APRIL

public static final Month APRIL

The singleton instance for the month of April with 30 days. This has the numeric value of 4.

MAY

public static final Month MAY

The singleton instance for the month of May with 31 days. This has the numeric value of 5.

JUNE

public static final Month JUNE

The singleton instance for the month of June with 30 days. This has the numeric value of 6.

JULY

public static final Month JULY

The singleton instance for the month of July with 31 days. This has the numeric value of 7.

AUGUST

public static final Month AUGUST

The singleton instance for the month of August with 31 days. This has the numeric value of 8.

SEPTEMBER

public static final Month SEPTEMBER

The singleton instance for the month of September with 30 days. This has the numeric value of 9.

OCTOBER

public static final Month OCTOBER

The singleton instance for the month of October with 31 days. This has the numeric value of 10.

NOVEMBER

public static final Month NOVEMBER

The singleton instance for the month of November with 30 days. This has the numeric value of 11.

DECEMBER

public static final Month DECEMBER

The singleton instance for the month of December with 31 days. This has the numeric value of 12.

Method Details

values

public static Month[] 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 Month 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 Month of(int month)

Obtains an instance of Month from an int value.

Month is an enum representing the 12 months of the year. This factory allows the enum to be obtained from the int value. The int value follows the ISO-8601 standard, from 1 (January) to 12 (December).

Parameters:

month - the month-of-year to represent, from 1 (January) to 12 (December)

Returns:

the month-of-year, not null

Throws:

DateTimeException - if the month-of-year is invalid

from

public static Month from(TemporalAccessor temporal)

Obtains an instance of Month from a temporal object.

This obtains a month based on the specified temporal. A TemporalAccessor represents an arbitrary set of date and time information, which this factory converts to an instance of Month.

The conversion extracts the MONTH_OF_YEAR field. The extraction is only permitted if the temporal object has an ISO chronology, or can be converted to a LocalDate.

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

Parameters:

temporal - the temporal object to convert, not null

Returns:

the month-of-year, not null

Throws:

DateTimeException - if unable to convert to a Month

getValue

public int getValue()

Gets the month-of-year int value.

The values are numbered following the ISO-8601 standard, from 1 (January) to 12 (December).

Returns:

the month-of-year, from 1 (January) to 12 (December)

getDisplayName

public String getDisplayName(TextStyle style,
 Locale locale)

Gets the textual representation, such as 'Jan' or 'December'.

This returns the textual name used to identify the month-of-year, 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 month-of-year, not null

isSupported

public boolean isSupported(TemporalField field)

Checks if the specified field is supported.

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

If the field is MONTH_OF_YEAR 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 month-of-year, 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 month 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 MONTH_OF_YEAR then the range of the month-of-year, from 1 to 12, 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 month-of-year as an int.

This queries this month 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 MONTH_OF_YEAR then the value of the month-of-year, from 1 to 12, 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 month-of-year as a long.

This queries this month 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 MONTH_OF_YEAR then the value of the month-of-year, from 1 to 12, 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 Month plus(long months)

Returns the month-of-year that is the specified number of months after this one.

The calculation rolls around the end of the year from December to January. The specified period may be negative.

This instance is immutable and unaffected by this method call.

Parameters:

months - the months to add, positive or negative

Returns:

the resulting month, not null

minus

public Month minus(long months)

Returns the month-of-year that is the specified number of months before this one.

The calculation rolls around the start of the year from January to December. The specified period may be negative.

This instance is immutable and unaffected by this method call.

Parameters:

months - the months to subtract, positive or negative

Returns:

the resulting month, not null

length

public int length(boolean leapYear)

Gets the length of this month in days.

This takes a flag to determine whether to return the length for a leap year or not.

February has 28 days in a standard year and 29 days in a leap year. April, June, September and November have 30 days. All other months have 31 days.

Parameters:

leapYear - true if the length is required for a leap year

Returns:

the length of this month in days, from 28 to 31

minLength

public int minLength()

Gets the minimum length of this month in days.

February has a minimum length of 28 days. April, June, September and November have 30 days. All other months have 31 days.

Returns:

the minimum length of this month in days, from 28 to 31

maxLength

public int maxLength()

Gets the maximum length of this month in days.

February has a maximum length of 29 days. April, June, September and November have 30 days. All other months have 31 days.

Returns:

the maximum length of this month in days, from 29 to 31

firstDayOfYear

public int firstDayOfYear(boolean leapYear)

Gets the day-of-year corresponding to the first day of this month.

This returns the day-of-year that this month begins on, using the leap year flag to determine the length of February.

Parameters:

leapYear - true if the length is required for a leap year

Returns:

the day of year corresponding to the first day of this month, from 1 to 336

firstMonthOfQuarter

public Month firstMonthOfQuarter()

Gets the month corresponding to the first month of this quarter.

The year can be divided into four quarters. This method returns the first month of the quarter for the base month. January, February and March return January. April, May and June return April. July, August and September return July. October, November and December return October.

Returns:

the first month of the quarter corresponding to this month, not null

query

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

Queries this month-of-year using the specified query.

This queries this month-of-year 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 month-of-year.

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

The adjustment is equivalent to using Temporal.with(TemporalField, long) passing ChronoField.MONTH_OF_YEAR as the field. If the specified temporal object does not use the ISO calendar system then a DateTimeException is thrown.

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 = thisMonth.adjustInto(temporal);
   temporal = temporal.with(thisMonth);
 

For example, given a date in May, the following are output:

   dateInMay.with(JANUARY);    // four months earlier
   dateInMay.with(APRIL);      // one months earlier
   dateInMay.with(MAY);        // same date
   dateInMay.with(JUNE);       // one month later
   dateInMay.with(DECEMBER);   // seven months 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