Package org.joda.time

Class DurationField

  • All Implemented Interfaces:
    java.lang.Comparable<DurationField>
    Direct Known Subclasses:
    BaseDurationField, DelegatedDurationField, MillisDurationField, UnsupportedDurationField
    public abstract class DurationField
extends java.lang.Object
implements java.lang.Comparable<DurationField>
    Defines the calculation engine for duration fields. The interface defines a set of methods that manipulate a millisecond duration with regards to a single field, such as months or seconds.

    This design is extensible so, if you wish, you can extract a different field from the millisecond duration. A number of standard implementations are provided to assist.

    Since:
    1.0

    • Constructor Summary

      Constructors 
      Constructor Description
      DurationField()  

    • Method Summary

      All Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method Description
      abstract long add​(long instant, int value)
      Adds a duration value (which may be negative) to the instant.
      abstract long add​(long instant, long value)
      Adds a duration value (which may be negative) to the instant.
      abstract int getDifference​(long minuendInstant, long subtrahendInstant)
      Computes the difference between two instants, as measured in the units of this field.
      abstract long getDifferenceAsLong​(long minuendInstant, long subtrahendInstant)
      Computes the difference between two instants, as measured in the units of this field.
      abstract long getMillis​(int value)
      Get the millisecond duration of this field from its value, which is approximate if this field is imprecise.
      abstract long getMillis​(int value, long instant)
      Get the millisecond duration of this field from its value relative to an instant.
      abstract long getMillis​(long value)
      Get the millisecond duration of this field from its value, which is approximate if this field is imprecise.
      abstract long getMillis​(long value, long instant)
      Get the millisecond duration of this field from its value relative to an instant.
      abstract java.lang.String getName()
      Get the name of the field.
      abstract DurationFieldType getType()
      Get the type of the field.
      abstract long getUnitMillis()
      Returns the amount of milliseconds per unit value of this field.
      abstract int getValue​(long duration)
      Get the value of this field from the milliseconds, which is approximate if this field is imprecise.
      abstract int getValue​(long duration, long instant)
      Get the value of this field from the milliseconds relative to an instant.
      abstract long getValueAsLong​(long duration)
      Get the value of this field from the milliseconds, which is approximate if this field is imprecise.
      abstract long getValueAsLong​(long duration, long instant)
      Get the value of this field from the milliseconds relative to an instant.
      abstract boolean isPrecise()
      Is this field precise.
      abstract boolean isSupported()
      Returns true if this field is supported.
      long subtract​(long instant, int value)
      Subtracts a duration value (which may be negative) from the instant.
      long subtract​(long instant, long value)
      Subtracts a duration value (which may be negative) from the instant.
      abstract java.lang.String toString()
      Get a suitable debug string.

      • Methods inherited from class java.lang.Object

        equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

      • Methods inherited from interface java.lang.Comparable

        compareTo

    • Constructor Detail

      • DurationField

        public DurationField()

    • Method Detail

      • getType

        public abstract DurationFieldType getType()
        Get the type of the field.
        Returns:
        field type

      • getName

        public abstract java.lang.String getName()
        Get the name of the field.

        By convention, names are plural.

        Returns:
        field name

      • isSupported

        public abstract boolean isSupported()
        Returns true if this field is supported.
        Returns:
        true if this field is supported

      • isPrecise

        public abstract boolean isPrecise()
        Is this field precise. A precise field can calculate its value from milliseconds without needing a reference date. Put another way, a precise field's unit size is not variable.
        Returns:
        true if precise
        See Also:
        getUnitMillis()

      • getUnitMillis

        public abstract long getUnitMillis()
        Returns the amount of milliseconds per unit value of this field. For example, if this field represents "seconds", then this returns the milliseconds in one second.

        For imprecise fields, the unit size is variable, and so this method returns a suitable average value.

        Returns:
        the unit size of this field, in milliseconds
        See Also:
        isPrecise()

      • getValue

        public abstract int getValue​(long duration)
        Get the value of this field from the milliseconds, which is approximate if this field is imprecise.
        Parameters:
        duration - the milliseconds to query, which may be negative
        Returns:
        the value of the field, in the units of the field, which may be negative
        Throws:
        java.lang.ArithmeticException - if the value is too large for an int

      • getValueAsLong

        public abstract long getValueAsLong​(long duration)
        Get the value of this field from the milliseconds, which is approximate if this field is imprecise.
        Parameters:
        duration - the milliseconds to query, which may be negative
        Returns:
        the value of the field, in the units of the field, which may be negative

      • getValue

        public abstract int getValue​(long duration,
                             long instant)
        Get the value of this field from the milliseconds relative to an instant. For precise fields this method produces the same result as for the single argument get method.

        If the millisecond duration is positive, then the instant is treated as a "start instant". If negative, the instant is treated as an "end instant".

        Parameters:
        duration - the milliseconds to query, which may be negative
        instant - the start instant to calculate relative to
        Returns:
        the value of the field, in the units of the field, which may be negative
        Throws:
        java.lang.ArithmeticException - if the value is too large for an int

      • getValueAsLong

        public abstract long getValueAsLong​(long duration,
                                    long instant)
        Get the value of this field from the milliseconds relative to an instant. For precise fields this method produces the same result as for the single argument get method.

        If the millisecond duration is positive, then the instant is treated as a "start instant". If negative, the instant is treated as an "end instant".

        Parameters:
        duration - the milliseconds to query, which may be negative
        instant - the start instant to calculate relative to
        Returns:
        the value of the field, in the units of the field, which may be negative

      • getMillis

        public abstract long getMillis​(int value)
        Get the millisecond duration of this field from its value, which is approximate if this field is imprecise.
        Parameters:
        value - the value of the field, which may be negative
        Returns:
        the milliseconds that the field represents, which may be negative

      • getMillis

        public abstract long getMillis​(long value)
        Get the millisecond duration of this field from its value, which is approximate if this field is imprecise.
        Parameters:
        value - the value of the field, which may be negative
        Returns:
        the milliseconds that the field represents, which may be negative

      • getMillis

        public abstract long getMillis​(int value,
                               long instant)
        Get the millisecond duration of this field from its value relative to an instant. For precise fields this method produces the same result as for the single argument getMillis method.

        If the value is positive, then the instant is treated as a "start instant". If negative, the instant is treated as an "end instant".

        Parameters:
        value - the value of the field, which may be negative
        instant - the instant to calculate relative to
        Returns:
        the millisecond duration that the field represents, which may be negative

      • getMillis

        public abstract long getMillis​(long value,
                               long instant)
        Get the millisecond duration of this field from its value relative to an instant. For precise fields this method produces the same result as for the single argument getMillis method.

        If the value is positive, then the instant is treated as a "start instant". If negative, the instant is treated as an "end instant".

        Parameters:
        value - the value of the field, which may be negative
        instant - the instant to calculate relative to
        Returns:
        the millisecond duration that the field represents, which may be negative

      • add

        public abstract long add​(long instant,
                         int value)
        Adds a duration value (which may be negative) to the instant.
        Parameters:
        instant - the milliseconds from 1970-01-01T00:00:00Z to add to
        value - the value to add, in the units of the field
        Returns:
        the updated milliseconds

      • add

        public abstract long add​(long instant,
                         long value)
        Adds a duration value (which may be negative) to the instant.
        Parameters:
        instant - the milliseconds from 1970-01-01T00:00:00Z to add to
        value - the value to add, in the units of the field
        Returns:
        the updated milliseconds

      • subtract

        public long subtract​(long instant,
                     int value)
        Subtracts a duration value (which may be negative) from the instant.
        Parameters:
        instant - the milliseconds from 1970-01-01T00:00:00Z to subtract from
        value - the value to subtract, in the units of the field
        Returns:
        the updated milliseconds
        Since:
        1.1

      • subtract

        public long subtract​(long instant,
                     long value)
        Subtracts a duration value (which may be negative) from the instant.
        Parameters:
        instant - the milliseconds from 1970-01-01T00:00:00Z to subtract from
        value - the value to subtract, in the units of the field
        Returns:
        the updated milliseconds
        Since:
        1.1

      • getDifference

        public abstract int getDifference​(long minuendInstant,
                                  long subtrahendInstant)
        Computes the difference between two instants, as measured in the units of this field. Any fractional units are dropped from the result. Calling getDifference reverses the effect of calling add. In the following code: 
         long instant = ...
 int v = ...
 int age = getDifference(add(instant, v), instant);
        The value 'age' is the same as the value 'v'.
        Parameters:
        minuendInstant - the milliseconds from 1970-01-01T00:00:00Z to subtract from
        subtrahendInstant - the milliseconds from 1970-01-01T00:00:00Z to subtract off the minuend
        Returns:
        the difference in the units of this field

      • getDifferenceAsLong

        public abstract long getDifferenceAsLong​(long minuendInstant,
                                         long subtrahendInstant)
        Computes the difference between two instants, as measured in the units of this field. Any fractional units are dropped from the result. Calling getDifference reverses the effect of calling add. In the following code: 
         long instant = ...
 long v = ...
 long age = getDifferenceAsLong(add(instant, v), instant);
        The value 'age' is the same as the value 'v'.
        Parameters:
        minuendInstant - the milliseconds from 1970-01-01T00:00:00Z to subtract from
        subtrahendInstant - the milliseconds from 1970-01-01T00:00:00Z to subtract off the minuend
        Returns:
        the difference in the units of this field

      • toString

        public abstract java.lang.String toString()
        Get a suitable debug string.
        Overrides:
        toString in class java.lang.Object
        Returns:
        debug string