Class Months

  • All Implemented Interfaces:
    java.io.Serializable, java.lang.Comparable<Months>, java.time.temporal.TemporalAmount

    public final class Months
    extends java.lang.Object
    implements java.time.temporal.TemporalAmount, java.lang.Comparable<Months>, java.io.Serializable
    A month-based amount of time, such as '12 months'.

    This class models a quantity or amount of time in terms of months. It is a type-safe way of representing a number of months in an application.

    The model is of a directed amount, meaning that the amount may be negative.

    Implementation Requirements:

    This class is immutable and thread-safe.

    This class must be treated as a value type. Do not synchronize, rely on the identity hash code or use the distinction between equals() and ==.

    See Also:
    Serialized Form
    • Field Summary

      Fields 
      Modifier and Type Field Description
      static Months ONE
      A constant for one month.
      static Months ZERO
      A constant for zero months.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      Months abs()
      Returns a copy of this duration with a positive length.
      java.time.temporal.Temporal addTo​(java.time.temporal.Temporal temporal)
      Adds this amount to the specified temporal object.
      static Months between​(java.time.temporal.Temporal startDateInclusive, java.time.temporal.Temporal endDateExclusive)
      Obtains a Months consisting of the number of months between two dates.
      int compareTo​(Months otherAmount)
      Compares this amount to the specified Months.
      Months dividedBy​(int divisor)
      Returns an instance with the amount divided by the specified divisor.
      boolean equals​(java.lang.Object otherAmount)
      Checks if this amount is equal to the specified Months.
      static Months from​(java.time.temporal.TemporalAmount amount)
      Obtains an instance of Months from a temporal amount.
      long get​(java.time.temporal.TemporalUnit unit)
      Gets the value of the requested unit.
      int getAmount()
      Gets the number of months in this amount.
      java.util.List<java.time.temporal.TemporalUnit> getUnits()
      Gets the set of units supported by this amount.
      int hashCode()
      A hash code for this amount.
      Months minus​(int months)
      Returns a copy of this amount with the specified number of months subtracted.
      Months minus​(java.time.temporal.TemporalAmount amountToAdd)
      Returns a copy of this amount with the specified amount subtracted.
      Months multipliedBy​(int scalar)
      Returns an instance with the amount multiplied by the specified scalar.
      Months negated()
      Returns an instance with the amount negated.
      static Months of​(int months)
      Obtains a Months representing a number of months.
      static Months ofYears​(int years)
      Obtains a Months representing the number of months equivalent to a number of years.
      static Months parse​(java.lang.CharSequence text)
      Obtains a Months from a text string such as PnM.
      Months plus​(int months)
      Returns a copy of this amount with the specified number of months added.
      Months plus​(java.time.temporal.TemporalAmount amountToAdd)
      Returns a copy of this amount with the specified amount added.
      java.time.temporal.Temporal subtractFrom​(java.time.temporal.Temporal temporal)
      Subtracts this amount from the specified temporal object.
      java.time.Period toPeriod()
      Gets the number of months as a Period.
      java.lang.String toString()
      Returns a string representation of the number of months.
      • Methods inherited from class java.lang.Object

        clone, finalize, getClass, notify, notifyAll, wait, wait, wait
    • Field Detail

      • ZERO

        public static final Months ZERO
        A constant for zero months.
      • ONE

        public static final Months ONE
        A constant for one month.
    • Method Detail

      • of

        public static Months of​(int months)
        Obtains a Months representing a number of months.

        The resulting amount will have the specified months.

        Parameters:
        months - the number of months, positive or negative
        Returns:
        the number of months, not null
      • ofYears

        public static Months ofYears​(int years)
        Obtains a Months representing the number of months equivalent to a number of years.

        The resulting amount will be month-based, with the number of months equal to the number of years multiplied by 12.

        Parameters:
        years - the number of years, positive or negative
        Returns:
        the amount with the input years converted to months, not null
        Throws:
        java.lang.ArithmeticException - if numeric overflow occurs
      • from

        public static Months from​(java.time.temporal.TemporalAmount amount)
        Obtains an instance of Months from a temporal amount.

        This obtains an instance based on the specified amount. A TemporalAmount represents an amount of time, which may be date-based or time-based, which this factory extracts to a Months.

        The result is calculated by looping around each unit in the specified amount. Each amount is converted to months using Temporals.convertAmount(long, java.time.temporal.TemporalUnit, java.time.temporal.TemporalUnit). If the conversion yields a remainder, an exception is thrown. If the amount is zero, the unit is ignored.

        Parameters:
        amount - the temporal amount to convert, not null
        Returns:
        the equivalent amount, not null
        Throws:
        java.time.DateTimeException - if unable to convert to a Months
        java.lang.ArithmeticException - if numeric overflow occurs
      • parse

        public static Months parse​(java.lang.CharSequence text)
        Obtains a Months from a text string such as PnM.

        This will parse the string produced by toString() which is based on the ISO-8601 period format PnYnM.

        The string starts with an optional sign, denoted by the ASCII negative or positive symbol. If negative, the whole amount is negated. The ASCII letter "P" is next in upper or lower case. There are then two sections, each consisting of a number and a suffix. At least one of the two sections must be present. The sections have suffixes in ASCII of "Y" and "M" for years and months, accepted in upper or lower case. The suffixes must occur in order. The number part of each section must consist of ASCII digits. The number may be prefixed by the ASCII negative or positive symbol. The number must parse to an int.

        The leading plus/minus sign, and negative values for years and months are not part of the ISO-8601 standard.

        For example, the following are valid inputs:

           "P2M"             -- Months.of(2)
           "P-2M"            -- Months.of(-2)
           "-P2M"            -- Months.of(-2)
           "-P-2M"           -- Months.of(2)
           "P3Y"             -- Months.of(3 * 12)
           "P3Y-2M"          -- Months.of(3 * 12 - 2)
         
        Parameters:
        text - the text to parse, not null
        Returns:
        the parsed period, not null
        Throws:
        java.time.format.DateTimeParseException - if the text cannot be parsed to a period
      • between

        public static Months between​(java.time.temporal.Temporal startDateInclusive,
                                     java.time.temporal.Temporal endDateExclusive)
        Obtains a Months consisting of the number of months between two dates.

        The start date is included, but the end date is not. The result of this method can be negative if the end is before the start.

        Parameters:
        startDateInclusive - the start date, inclusive, not null
        endDateExclusive - the end date, exclusive, not null
        Returns:
        the number of months between this date and the end date, not null
      • get

        public long get​(java.time.temporal.TemporalUnit unit)
        Gets the value of the requested unit.

        This returns a value for the supported unit - MONTHS. All other units throw an exception.

        Specified by:
        get in interface java.time.temporal.TemporalAmount
        Parameters:
        unit - the TemporalUnit for which to return the value
        Returns:
        the long value of the unit
        Throws:
        java.time.temporal.UnsupportedTemporalTypeException - if the unit is not supported
      • getUnits

        public java.util.List<java.time.temporal.TemporalUnit> getUnits()
        Gets the set of units supported by this amount.

        The single supported unit is MONTHS.

        This set can be used in conjunction with get(TemporalUnit) to access the entire state of the amount.

        Specified by:
        getUnits in interface java.time.temporal.TemporalAmount
        Returns:
        a list containing the months unit, not null
      • getAmount

        public int getAmount()
        Gets the number of months in this amount.
        Returns:
        the number of months
      • plus

        public Months plus​(java.time.temporal.TemporalAmount amountToAdd)
        Returns a copy of this amount with the specified amount added.

        The parameter is converted using from(TemporalAmount).

        This instance is immutable and unaffected by this method call.

        Parameters:
        amountToAdd - the amount to add, not null
        Returns:
        a Months based on this instance with the requested amount added, not null
        Throws:
        java.time.DateTimeException - if the specified amount contains an invalid unit
        java.lang.ArithmeticException - if numeric overflow occurs
      • plus

        public Months plus​(int months)
        Returns a copy of this amount with the specified number of months added.

        This instance is immutable and unaffected by this method call.

        Parameters:
        months - the amount of months to add, may be negative
        Returns:
        a Months based on this instance with the requested amount added, not null
        Throws:
        java.lang.ArithmeticException - if the result overflows an int
      • minus

        public Months minus​(java.time.temporal.TemporalAmount amountToAdd)
        Returns a copy of this amount with the specified amount subtracted.

        The parameter is converted using from(TemporalAmount).

        This instance is immutable and unaffected by this method call.

        Parameters:
        amountToAdd - the amount to add, not null
        Returns:
        a Months based on this instance with the requested amount subtracted, not null
        Throws:
        java.time.DateTimeException - if the specified amount contains an invalid unit
        java.lang.ArithmeticException - if numeric overflow occurs
      • minus

        public Months minus​(int months)
        Returns a copy of this amount with the specified number of months subtracted.

        This instance is immutable and unaffected by this method call.

        Parameters:
        months - the amount of months to add, may be negative
        Returns:
        a Months based on this instance with the requested amount subtracted, not null
        Throws:
        java.lang.ArithmeticException - if the result overflows an int
      • multipliedBy

        public Months multipliedBy​(int scalar)
        Returns an instance with the amount multiplied by the specified scalar.

        This instance is immutable and unaffected by this method call.

        Parameters:
        scalar - the scalar to multiply by, not null
        Returns:
        the amount multiplied by the specified scalar, not null
        Throws:
        java.lang.ArithmeticException - if numeric overflow occurs
      • dividedBy

        public Months dividedBy​(int divisor)
        Returns an instance with the amount divided by the specified divisor.

        The calculation uses integer division, thus 3 divided by 2 is 1.

        This instance is immutable and unaffected by this method call.

        Parameters:
        divisor - the amount to divide by, may be negative
        Returns:
        the amount divided by the specified divisor, not null
        Throws:
        java.lang.ArithmeticException - if the divisor is zero
      • negated

        public Months negated()
        Returns an instance with the amount negated.

        This instance is immutable and unaffected by this method call.

        Returns:
        the negated amount, not null
        Throws:
        java.lang.ArithmeticException - if numeric overflow occurs, which only happens if the amount is Long.MIN_VALUE
      • abs

        public Months abs()
        Returns a copy of this duration with a positive length.

        This method returns a positive duration by effectively removing the sign from any negative total length.

        This instance is immutable and unaffected by this method call.

        Returns:
        the absolute amount, not null
        Throws:
        java.lang.ArithmeticException - if numeric overflow occurs, which only happens if the amount is Long.MIN_VALUE
      • toPeriod

        public java.time.Period toPeriod()
        Gets the number of months as a Period.

        This returns a period with the same number of months.

        Returns:
        the equivalent period, not null
      • addTo

        public java.time.temporal.Temporal addTo​(java.time.temporal.Temporal temporal)
        Adds this amount to the specified temporal object.

        This returns a temporal object of the same observable type as the input with this amount added.

        In most cases, it is clearer to reverse the calling pattern by using Temporal.plus(TemporalAmount).

           // these two lines are equivalent, but the second approach is recommended
           dateTime = thisAmount.addTo(dateTime);
           dateTime = dateTime.plus(thisAmount);
         

        Only non-zero amounts will be added.

        This instance is immutable and unaffected by this method call.

        Specified by:
        addTo in interface java.time.temporal.TemporalAmount
        Parameters:
        temporal - the temporal object to adjust, not null
        Returns:
        an object of the same type with the adjustment made, not null
        Throws:
        java.time.DateTimeException - if unable to add
        java.time.temporal.UnsupportedTemporalTypeException - if the MONTHS unit is not supported
        java.lang.ArithmeticException - if numeric overflow occurs
      • subtractFrom

        public java.time.temporal.Temporal subtractFrom​(java.time.temporal.Temporal temporal)
        Subtracts this amount from the specified temporal object.

        This returns a temporal object of the same observable type as the input with this amount subtracted.

        In most cases, it is clearer to reverse the calling pattern by using Temporal.minus(TemporalAmount).

           // these two lines are equivalent, but the second approach is recommended
           dateTime = thisAmount.subtractFrom(dateTime);
           dateTime = dateTime.minus(thisAmount);
         

        Only non-zero amounts will be subtracted.

        This instance is immutable and unaffected by this method call.

        Specified by:
        subtractFrom in interface java.time.temporal.TemporalAmount
        Parameters:
        temporal - the temporal object to adjust, not null
        Returns:
        an object of the same type with the adjustment made, not null
        Throws:
        java.time.DateTimeException - if unable to subtract
        java.time.temporal.UnsupportedTemporalTypeException - if the MONTHS unit is not supported
        java.lang.ArithmeticException - if numeric overflow occurs
      • compareTo

        public int compareTo​(Months otherAmount)
        Compares this amount to the specified Months.

        The comparison is based on the total length of the amounts. It is "consistent with equals", as defined by Comparable.

        Specified by:
        compareTo in interface java.lang.Comparable<Months>
        Parameters:
        otherAmount - the other amount, not null
        Returns:
        the comparator value, negative if less, positive if greater
      • equals

        public boolean equals​(java.lang.Object otherAmount)
        Checks if this amount is equal to the specified Months.

        The comparison is based on the total length of the durations.

        Overrides:
        equals in class java.lang.Object
        Parameters:
        otherAmount - the other amount, null returns false
        Returns:
        true if the other amount is equal to this one
      • hashCode

        public int hashCode()
        A hash code for this amount.
        Overrides:
        hashCode in class java.lang.Object
        Returns:
        a suitable hash code
      • toString

        public java.lang.String toString()
        Returns a string representation of the number of months. This will be in the format 'PnM' where n is the number of months.
        Overrides:
        toString in class java.lang.Object
        Returns:
        the number of months in ISO-8601 string format