public abstract class

DurationField

extends Object
implements Comparable<T>
java.lang.Object
   ↳ org.joda.time.DurationField
Known Direct Subclasses
Known Indirect Subclasses

Class Overview

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.

Summary

Public Constructors
DurationField()
Public Methods
abstract long add(long instant, long value)
Adds a duration value (which may be negative) to the instant.
abstract long add(long instant, int value)
Adds a duration value (which may be negative) to the instant.
abstract int compareTo(Object durationField)
Compares this duration field with another duration field for ascending unit millisecond order.
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(long value, long instant)
Get the millisecond duration of this field from its value relative to an instant.
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 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, long value)
Subtracts a duration value (which may be negative) from the instant.
long subtract(long instant, int value)
Subtracts a duration value (which may be negative) from the instant.
abstract String toString()
Get a suitable debug string.
[Expand]
Inherited Methods
From class java.lang.Object
From interface java.lang.Comparable

Public Constructors

public DurationField ()

Public Methods

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

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

public abstract int compareTo (Object durationField)

Compares this duration field with another duration field for ascending unit millisecond order. This ordering is inconsistent with equals, as it ignores name and precision.

Parameters
durationField a duration field to check against
Returns
  • negative value if this is less, 0 if equal, or positive value if greater
Throws
NullPointerException if the object is null
ClassCastException if the object type is not supported

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

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

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

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

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

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

public abstract String getName ()

Get the name of the field.

By convention, names are plural.

Returns
  • field name

public abstract DurationFieldType getType ()

Get the type of the field.

Returns
  • field type

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

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

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

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

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

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

public abstract boolean isSupported ()

Returns true if this field is supported.

Returns
  • true if this field is supported

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

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

public abstract String toString ()

Get a suitable debug string.

Returns
  • debug string