Enum Month

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Comparable<Month>, TemporalAccessor, TemporalAdjuster

    public enum Month
    extends java.lang.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.

    Specification for implementors

    This is an immutable and thread-safe enum.
    • 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.
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static TemporalQuery<Month> FROM
      Simulate JDK 8 method reference Month::from.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      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.
      java.lang.String getDisplayName​(TextStyle style, java.util.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​(java.lang.String name)
      Returns the enum constant of this type with the specified name.
      static Month[] values()
      Returns an array containing the constants of this enum type, in the order they are declared.
      • Methods inherited from class java.lang.Enum

        clone, compareTo, equals, finalize, getDeclaringClass, hashCode, name, ordinal, toString, valueOf
      • Methods inherited from class java.lang.Object

        getClass, notify, notifyAll, wait, wait, wait
    • Enum Constant Detail

      • 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.
    • Field Detail

      • FROM

        public static final TemporalQuery<Month> FROM
        Simulate JDK 8 method reference Month::from.
    • Method Detail

      • values

        public static Month[] values()
        Returns an array containing the constants of this enum type, in the order they are declared. This method may be used to iterate over the constants as follows:
        for (Month c : Month.values())
            System.out.println(c);
        
        Returns:
        an array containing the constants of this enum type, in the order they are declared
      • valueOf

        public static Month valueOf​(java.lang.String name)
        Returns the enum constant of this type with the specified name. The string must match exactly an identifier used to declare an enum constant in this type. (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:
        java.lang.IllegalArgumentException - if this enum type has no constant with the specified name
        java.lang.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.

        A TemporalAccessor represents some form of date and time information. This factory converts the arbitrary temporal object 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 in queries 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 java.lang.String getDisplayName​(TextStyle style,
                                               java.util.Locale locale)
        Gets the textual representation, such as 'Jan' or 'December'.

        This returns the textual name used to identify the month-of-year. The parameters control the length 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 a DateTimeException.

        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
      • 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 for 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 a DateTimeException.

        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
        DateTimeException - if the range of valid values for the field exceeds an int
        DateTimeException - if the value is outside the range of valid values for the field
        java.lang.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 for 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 a DateTimeException.

        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
        java.lang.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)
        java.lang.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
        java.lang.ArithmeticException - if numeric overflow occurs