Package org.joda.time

Class YearMonth

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Comparable<ReadablePartial>, ReadablePartial
    public final class YearMonth
extends BasePartial
implements ReadablePartial, java.io.Serializable
    YearMonth is an immutable partial supporting the year and monthOfYear fields.

    NOTE: This class only supports the two fields listed above. It is impossible to query any other fields, such as dayOfWeek or centuryOfEra.

    Calculations on YearMonth are performed using a Chronology. This chronology is set to be in the UTC time zone for all calculations.

    One use case for this class is to store a credit card expiry date, as that only references the year and month. This class can be used as the gYearMonth type in XML Schema.

    Each individual field can be queried in two ways:

    • getMonthOfYear()
    • monthOfYear().get()
    The second technique also provides access to other useful methods on the field:
    • numeric value - monthOfYear().get()
    • text value - monthOfYear().getAsText()
    • short text value - monthOfYear().getAsShortText()
    • maximum/minimum values - monthOfYear().getMaximumValue()
    • add/subtract - monthOfYear().addToCopy()
    • set - monthOfYear().setCopy()

    YearMonth is thread-safe and immutable, provided that the Chronology is as well. All standard Chronology classes supplied are thread-safe and immutable.

    Since:
    2.0
    See Also:
    Serialized Form

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description
      static class  YearMonth.Property
      The property class for YearMonth.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static int MONTH_OF_YEAR
      The index of the monthOfYear field in the field array
      static int YEAR
      The index of the year field in the field array

    • Constructor Summary

      Constructors 
      Constructor Description
      YearMonth()
      Constructs a YearMonth with the current year-month, using ISOChronology in the default zone to extract the fields.
      YearMonth​(int year, int monthOfYear)
      Constructs a YearMonth with specified year and month using ISOChronology.
      YearMonth​(int year, int monthOfYear, Chronology chronology)
      Constructs an instance set to the specified year and month using the specified chronology, whose zone is ignored.
      YearMonth​(long instant)
      Constructs a YearMonth extracting the partial fields from the specified milliseconds using the ISOChronology in the default zone.
      YearMonth​(long instant, Chronology chronology)
      Constructs a YearMonth extracting the partial fields from the specified milliseconds using the chronology provided.
      YearMonth​(java.lang.Object instant)
      Constructs a YearMonth from an Object that represents some form of time.
      YearMonth​(java.lang.Object instant, Chronology chronology)
      Constructs a YearMonth from an Object that represents some form of time, using the specified chronology.
      YearMonth​(Chronology chronology)
      Constructs a YearMonth with the current year-month, using the specified chronology and zone to extract the fields.
      YearMonth​(DateTimeZone zone)
      Constructs a YearMonth with the current year-month, using ISOChronology in the specified zone to extract the fields.

    • Field Detail

      • YEAR

        public static final int YEAR
        The index of the year field in the field array
        See Also:
        Constant Field Values

      • MONTH_OF_YEAR

        public static final int MONTH_OF_YEAR
        The index of the monthOfYear field in the field array
        See Also:
        Constant Field Values

    • Constructor Detail

      • YearMonth

        public YearMonth()
        Constructs a YearMonth with the current year-month, using ISOChronology in the default zone to extract the fields.

        The constructor uses the default time zone, resulting in the local time being initialised. Once the constructor is complete, all further calculations are performed without reference to a time-zone (by switching to UTC).

        See Also:
        now()

      • YearMonth

        public YearMonth​(DateTimeZone zone)
        Constructs a YearMonth with the current year-month, using ISOChronology in the specified zone to extract the fields.

        The constructor uses the specified time zone to obtain the current year-month. Once the constructor is complete, all further calculations are performed without reference to a time-zone (by switching to UTC).

        Parameters:
        zone - the zone to use, null means default zone
        See Also:
        now(DateTimeZone)

      • YearMonth

        public YearMonth​(Chronology chronology)
        Constructs a YearMonth with the current year-month, using the specified chronology and zone to extract the fields.

        The constructor uses the time zone of the chronology specified. Once the constructor is complete, all further calculations are performed without reference to a time-zone (by switching to UTC).

        Parameters:
        chronology - the chronology, null means ISOChronology in the default zone
        See Also:
        now(Chronology)

      • YearMonth

        public YearMonth​(long instant)
        Constructs a YearMonth extracting the partial fields from the specified milliseconds using the ISOChronology in the default zone.

        The constructor uses the default time zone, resulting in the local time being initialised. Once the constructor is complete, all further calculations are performed without reference to a time-zone (by switching to UTC).

        Parameters:
        instant - the milliseconds from 1970-01-01T00:00:00Z

      • YearMonth

        public YearMonth​(long instant,
                 Chronology chronology)
        Constructs a YearMonth extracting the partial fields from the specified milliseconds using the chronology provided.

        The constructor uses the time zone of the chronology specified. Once the constructor is complete, all further calculations are performed without reference to a time-zone (by switching to UTC).

        Parameters:
        instant - the milliseconds from 1970-01-01T00:00:00Z
        chronology - the chronology, null means ISOChronology in the default zone

      • YearMonth

        public YearMonth​(java.lang.Object instant)
        Constructs a YearMonth from an Object that represents some form of time.

        The recognised object types are defined in ConverterManager and include ReadableInstant, String, Calendar and Date. The String formats are described by ISODateTimeFormat.localDateParser().

        The chronology used will be derived from the object, defaulting to ISO.

        Parameters:
        instant - the date-time object, null means now
        Throws:
        java.lang.IllegalArgumentException - if the instant is invalid

      • YearMonth

        public YearMonth​(java.lang.Object instant,
                 Chronology chronology)
        Constructs a YearMonth from an Object that represents some form of time, using the specified chronology.

        The recognised object types are defined in ConverterManager and include ReadableInstant, String, Calendar and Date. The String formats are described by ISODateTimeFormat.localDateParser().

        The constructor uses the time zone of the chronology specified. Once the constructor is complete, all further calculations are performed without reference to a time-zone (by switching to UTC). The specified chronology overrides that of the object.

        Parameters:
        instant - the date-time object, null means now
        chronology - the chronology, null means ISO default
        Throws:
        java.lang.IllegalArgumentException - if the instant is invalid

      • YearMonth

        public YearMonth​(int year,
                 int monthOfYear)
        Constructs a YearMonth with specified year and month using ISOChronology.

        The constructor uses the no time zone initialising the fields as provided. Once the constructor is complete, all further calculations are performed without reference to a time-zone (by switching to UTC).

        Parameters:
        year - the year
        monthOfYear - the month of the year

      • YearMonth

        public YearMonth​(int year,
                 int monthOfYear,
                 Chronology chronology)
        Constructs an instance set to the specified year and month using the specified chronology, whose zone is ignored.

        If the chronology is null, ISOChronology is used.

        The constructor uses the time zone of the chronology specified. Once the constructor is complete, all further calculations are performed without reference to a time-zone (by switching to UTC).

        Parameters:
        year - the year
        monthOfYear - the month of the year
        chronology - the chronology, null means ISOChronology in the default zone

    • Method Detail

      • now

        public static YearMonth now()
        Obtains a YearMonth set to the current system millisecond time using ISOChronology in the default time zone. The resulting object does not use the zone.
        Returns:
        the current year-month, not null
        Since:
        2.0

      • now

        public static YearMonth now​(DateTimeZone zone)
        Obtains a YearMonth set to the current system millisecond time using ISOChronology in the specified time zone. The resulting object does not use the zone.
        Parameters:
        zone - the time zone, not null
        Returns:
        the current year-month, not null
        Since:
        2.0

      • now

        public static YearMonth now​(Chronology chronology)
        Obtains a YearMonth set to the current system millisecond time using the specified chronology. The resulting object does not use the zone.
        Parameters:
        chronology - the chronology, not null
        Returns:
        the current year-month, not null
        Since:
        2.0

      • parse

        public static YearMonth parse​(java.lang.String str,
                              DateTimeFormatter formatter)
        Parses a YearMonth from the specified string using a formatter.
        Parameters:
        str - the string to parse, not null
        formatter - the formatter to use, not null
        Since:
        2.0

      • fromCalendarFields

        public static YearMonth fromCalendarFields​(java.util.Calendar calendar)
        Constructs a YearMonth from a java.util.Calendar using exactly the same field values avoiding any time zone effects.

        Each field is queried from the Calendar and assigned to the YearMonth.

        This factory method ignores the type of the calendar and always creates a YearMonth with ISO chronology. It is expected that you will only pass in instances of GregorianCalendar however this is not validated.

        Parameters:
        calendar - the Calendar to extract fields from
        Returns:
        the created YearMonth, never null
        Throws:
        java.lang.IllegalArgumentException - if the calendar is null
        java.lang.IllegalArgumentException - if the year or month is invalid for the ISO chronology

      • fromDateFields

        public static YearMonth fromDateFields​(java.util.Date date)
        Constructs a YearMonth from a java.util.Date using exactly the same field values avoiding any time zone effects.

        Each field is queried from the Date and assigned to the YearMonth.

        This factory method always creates a YearMonth with ISO chronology.

        Parameters:
        date - the Date to extract fields from
        Returns:
        the created YearMonth, never null
        Throws:
        java.lang.IllegalArgumentException - if the calendar is null
        java.lang.IllegalArgumentException - if the year or month is invalid for the ISO chronology

      • size

        public int size()
        Gets the number of fields in this partial, which is two. The supported fields are Year and MonthOfYear. Note that only these fields may be queried.
        Specified by:
        size in interface ReadablePartial
        Returns:
        the field count, two

      • getFieldType

        public DateTimeFieldType getFieldType​(int index)
        Gets the field type at the specified index.
        Specified by:
        getFieldType in interface ReadablePartial
        Overrides:
        getFieldType in class AbstractPartial
        Parameters:
        index - the index to retrieve
        Returns:
        the field at the specified index, never null
        Throws:
        java.lang.IndexOutOfBoundsException - if the index is invalid

      • getFieldTypes

        public DateTimeFieldType[] getFieldTypes()
        Gets an array of the field type of each of the fields that this partial supports.

        The fields are returned largest to smallest, Year, Month.

        Overrides:
        getFieldTypes in class AbstractPartial
        Returns:
        the array of field types (cloned), largest to smallest, never null

      • withChronologyRetainFields

        public YearMonth withChronologyRetainFields​(Chronology newChronology)
        Returns a copy of this year-month with the specified chronology. This instance is immutable and unaffected by this method call.

        This method retains the values of the fields, thus the result will typically refer to a different instant.

        The time zone of the specified chronology is ignored, as YearMonth operates without a time zone.

        Parameters:
        newChronology - the new chronology, null means ISO
        Returns:
        a copy of this year-month with a different chronology, never null
        Throws:
        java.lang.IllegalArgumentException - if the values are invalid for the new chronology

      • withField

        public YearMonth withField​(DateTimeFieldType fieldType,
                           int value)
        Returns a copy of this year-month with the specified field set to a new value.

        For example, if the field type is monthOfYear then the month would be changed in the returned instance.

        These three lines are equivalent: 

         YearMonth updated = ym.withField(DateTimeFieldType.monthOfYear(), 6);
 YearMonth updated = ym.monthOfYear().setCopy(6);
 YearMonth updated = ym.property(DateTimeFieldType.monthOfYear()).setCopy(6);
        Parameters:
        fieldType - the field type to set, not null
        value - the value to set
        Returns:
        a copy of this instance with the field set, never null
        Throws:
        java.lang.IllegalArgumentException - if the value is null or invalid

      • withFieldAdded

        public YearMonth withFieldAdded​(DurationFieldType fieldType,
                                int amount)
        Returns a copy of this year-month with the value of the specified field increased.

        If the addition is zero, then this is returned.

        These three lines are equivalent: 

         YearMonth added = ym.withFieldAdded(DurationFieldType.months(), 6);
 YearMonth added = ym.plusMonths(6);
 YearMonth added = ym.monthOfYear().addToCopy(6);
        Parameters:
        fieldType - the field type to add to, not null
        amount - the amount to add
        Returns:
        a copy of this instance with the field updated, never null
        Throws:
        java.lang.IllegalArgumentException - if the value is null or invalid
        java.lang.ArithmeticException - if the new date-time exceeds the capacity

      • withPeriodAdded

        public YearMonth withPeriodAdded​(ReadablePeriod period,
                                 int scalar)
        Returns a copy of this year-month with the specified period added.

        If the addition is zero, then this is returned. Fields in the period that aren't present in the partial are ignored.

        This method is typically used to add multiple copies of complex period instances. Adding one field is best achieved using methods like withFieldAdded(DurationFieldType, int) or plusYears(int).

        Parameters:
        period - the period to add to this one, null means zero
        scalar - the amount of times to add, such as -1 to subtract once
        Returns:
        a copy of this instance with the period added, never null
        Throws:
        java.lang.ArithmeticException - if the new date-time exceeds the capacity

      • plus

        public YearMonth plus​(ReadablePeriod period)
        Returns a copy of this year-month with the specified period added.

        If the amount is zero or null, then this is returned.

        This method is typically used to add complex period instances. Adding one field is best achieved using methods like plusYears(int).

        Parameters:
        period - the duration to add to this one, null means zero
        Returns:
        a copy of this instance with the period added, never null
        Throws:
        java.lang.ArithmeticException - if the new year-month exceeds the capacity

      • plusYears

        public YearMonth plusYears​(int years)
        Returns a copy of this year-month plus the specified number of years.

        This year-month instance is immutable and unaffected by this method call.

        The following three lines are identical in effect: 

         YearMonth added = ym.plusYears(6);
 YearMonth added = ym.plus(Period.years(6));
 YearMonth added = ym.withFieldAdded(DurationFieldType.years(), 6);
        Parameters:
        years - the amount of years to add, may be negative
        Returns:
        the new year-month plus the increased years, never null

      • plusMonths

        public YearMonth plusMonths​(int months)
        Returns a copy of this year-month plus the specified number of months.

        This year-month instance is immutable and unaffected by this method call.

        The following three lines are identical in effect: 

         YearMonth added = ym.plusMonths(6);
 YearMonth added = ym.plus(Period.months(6));
 YearMonth added = ym.withFieldAdded(DurationFieldType.months(), 6);
        Parameters:
        months - the amount of months to add, may be negative
        Returns:
        the new year-month plus the increased months, never null

      • minus

        public YearMonth minus​(ReadablePeriod period)
        Returns a copy of this year-month with the specified period taken away.

        If the amount is zero or null, then this is returned.

        This method is typically used to subtract complex period instances. Subtracting one field is best achieved using methods like minusYears(int).

        Parameters:
        period - the period to reduce this instant by
        Returns:
        a copy of this instance with the period taken away, never null
        Throws:
        java.lang.ArithmeticException - if the new year-month exceeds the capacity

      • minusYears

        public YearMonth minusYears​(int years)
        Returns a copy of this year-month minus the specified number of years.

        This year-month instance is immutable and unaffected by this method call.

        The following three lines are identical in effect: 

         YearMonth subtracted = ym.minusYears(6);
 YearMonth subtracted = ym.minus(Period.years(6));
 YearMonth subtracted = ym.withFieldAdded(DurationFieldType.years(), -6);
        Parameters:
        years - the amount of years to subtract, may be negative
        Returns:
        the new year-month minus the increased years, never null

      • minusMonths

        public YearMonth minusMonths​(int months)
        Returns a copy of this year-month minus the specified number of months.

        This year-month instance is immutable and unaffected by this method call.

        The following three lines are identical in effect: 

         YearMonth subtracted = ym.minusMonths(6);
 YearMonth subtracted = ym.minus(Period.months(6));
 YearMonth subtracted = ym.withFieldAdded(DurationFieldType.months(), -6);
        Parameters:
        months - the amount of months to subtract, may be negative
        Returns:
        the new year-month minus the increased months, never null

      • toLocalDate

        public LocalDate toLocalDate​(int dayOfMonth)
        Converts this object to a LocalDate with the same year-month and chronology.
        Parameters:
        dayOfMonth - the day of month to use, valid for chronology, such as 1-31 for ISO
        Returns:
        a LocalDate with the same year-month and chronology, never null

      • toInterval

        public Interval toInterval()
        Converts this object to an Interval representing the whole month.

        The interval will use the chronology of the year-month in the default zone.

        This instance is immutable and unaffected by this method call.

        Returns:
        an interval over the month, never null

      • toInterval

        public Interval toInterval​(DateTimeZone zone)
        Converts this object to an Interval representing the whole month.

        The interval will use the chronology of the year-month in the specified zone.

        This instance is immutable and unaffected by this method call.

        Parameters:
        zone - the zone to get the Interval in, null means default
        Returns:
        an interval over the month, never null

      • getYear

        public int getYear()
        Get the year field value.
        Returns:
        the year

      • getMonthOfYear

        public int getMonthOfYear()
        Get the month of year field value.
        Returns:
        the month of year

      • withYear

        public YearMonth withYear​(int year)
        Returns a copy of this year-month with the year field updated.

        YearMonth is immutable, so there are no set methods. Instead, this method returns a new instance with the value of year changed.

        Parameters:
        year - the year to set
        Returns:
        a copy of this object with the field set, never null
        Throws:
        java.lang.IllegalArgumentException - if the value is invalid

      • withMonthOfYear

        public YearMonth withMonthOfYear​(int monthOfYear)
        Returns a copy of this year-month with the month of year field updated.

        YearMonth is immutable, so there are no set methods. Instead, this method returns a new instance with the value of month of year changed.

        Parameters:
        monthOfYear - the month of year to set
        Returns:
        a copy of this object with the field set, never null
        Throws:
        java.lang.IllegalArgumentException - if the value is invalid

      • property

        public YearMonth.Property property​(DateTimeFieldType type)
        Gets the property object for the specified type, which contains many useful methods.
        Parameters:
        type - the field type to get the property for
        Returns:
        the property object
        Throws:
        java.lang.IllegalArgumentException - if the field is null or unsupported

      • year

        public YearMonth.Property year()
        Get the year field property which provides access to advanced functionality.
        Returns:
        the year property

      • monthOfYear

        public YearMonth.Property monthOfYear()
        Get the month of year field property which provides access to advanced functionality.
        Returns:
        the month of year property

      • toString

        public java.lang.String toString()
        Output the year-month in ISO8601 format (yyyy-MM).
        Specified by:
        toString in interface ReadablePartial
        Overrides:
        toString in class java.lang.Object
        Returns:
        ISO8601 time formatted string.

      • toString

        public java.lang.String toString​(java.lang.String pattern)
        Output the year-month using the specified format pattern.
        Overrides:
        toString in class BasePartial
        Parameters:
        pattern - the pattern specification, null means use toString
        See Also:
        DateTimeFormat

      • toString

        public java.lang.String toString​(java.lang.String pattern,
                                 java.util.Locale locale)
                          throws java.lang.IllegalArgumentException
        Output the year-month using the specified format pattern.
        Overrides:
        toString in class BasePartial
        Parameters:
        pattern - the pattern specification, null means use toString
        locale - Locale to use, null means default
        Throws:
        java.lang.IllegalArgumentException
        See Also:
        DateTimeFormat