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