Package org.joda.time

Class DurationField

java.lang.Object
org.joda.time.DurationField
All Implemented Interfaces:
Comparable<DurationField>
Direct Known Subclasses:
BaseDurationField, DelegatedDurationField, MillisDurationField, UnsupportedDurationField

public abstract class DurationField extends Object implements 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
Author:
Stephen Colebourne, Brian S O'Neill
  • Constructor Summary

    Constructors
    Constructor
    Description
     
  • Method Summary

    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 String
    Get the name of the field.
    Get the type of the field.
    abstract long
    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
    Is this field precise.
    abstract boolean
    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 String
    Get a suitable debug string.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

    Methods inherited from interface java.lang.Comparable

    compareTo
  • Constructor Details

    • DurationField

      public DurationField()
  • Method Details

    • getType

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

      public abstract 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

      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:
    • 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:
      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:
      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 String toString()
      Get a suitable debug string.
      Overrides:
      toString in class Object
      Returns:
      debug string