org.joda.time.field
Class DecoratedDurationField

java.lang.Object
  extended by org.joda.time.DurationField
      extended by org.joda.time.field.BaseDurationField
          extended by org.joda.time.field.DecoratedDurationField
All Implemented Interfaces:
Serializable, Comparable<DurationField>
Direct Known Subclasses:
ScaledDurationField

public class DecoratedDurationField
extends BaseDurationField

DecoratedDurationField extends BaseDurationField, implementing only the minimum required set of methods. These implemented methods delegate to a wrapped field.

This design allows new DurationField types to be defined that piggyback on top of another, inheriting all the safe method implementations from BaseDurationField. Should any method require pure delegation to the wrapped field, simply override and use the provided getWrappedField method.

DecoratedDurationField is thread-safe and immutable, and its subclasses must be as well.

Since:
1.0
Author:
Brian S O'Neill
See Also:
DelegatedDurationField, Serialized Form

Constructor Summary
DecoratedDurationField(DurationField field, DurationFieldType type)
          Constructor.
 
Method Summary
 long add(long instant, int value)
          Adds a duration value (which may be negative) to the instant.
 long add(long instant, long value)
          Adds a duration value (which may be negative) to the instant.
 long getDifferenceAsLong(long minuendInstant, long subtrahendInstant)
          Computes the difference between two instants, as measured in the units of this field.
 long getMillis(int value, long instant)
          Get the millisecond duration of this field from its value relative to an instant.
 long getMillis(long value, long instant)
          Get the millisecond duration of this field from its value relative to an instant.
 long getUnitMillis()
          Returns the amount of milliseconds per unit value of this field.
 long getValueAsLong(long duration, long instant)
          Get the value of this field from the milliseconds relative to an instant.
 DurationField getWrappedField()
          Gets the wrapped duration field.
 boolean isPrecise()
          Is this field precise.
 
Methods inherited from class org.joda.time.field.BaseDurationField
compareTo, getDifference, getMillis, getMillis, getName, getType, getValue, getValue, getValueAsLong, isSupported, toString
 
Methods inherited from class org.joda.time.DurationField
subtract, subtract
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

DecoratedDurationField

public DecoratedDurationField(DurationField field,
                              DurationFieldType type)
Constructor.

Parameters:
field - the base field
type - the type to actually use
Method Detail

getWrappedField

public final DurationField getWrappedField()
Gets the wrapped duration field.

Returns:
the wrapped DurationField

isPrecise

public boolean isPrecise()
Description copied from class: DurationField
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.

Specified by:
isPrecise in class DurationField
Returns:
true if precise
See Also:
DurationField.getUnitMillis()

getValueAsLong

public long getValueAsLong(long duration,
                           long instant)
Description copied from class: DurationField
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".

Specified by:
getValueAsLong in class DurationField
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 long getMillis(int value,
                      long instant)
Description copied from class: DurationField
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".

Specified by:
getMillis in class DurationField
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 long getMillis(long value,
                      long instant)
Description copied from class: DurationField
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".

Specified by:
getMillis in class DurationField
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 long add(long instant,
                int value)
Description copied from class: DurationField
Adds a duration value (which may be negative) to the instant.

Specified by:
add in class DurationField
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 long add(long instant,
                long value)
Description copied from class: DurationField
Adds a duration value (which may be negative) to the instant.

Specified by:
add in class DurationField
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

getDifferenceAsLong

public long getDifferenceAsLong(long minuendInstant,
                                long subtrahendInstant)
Description copied from class: DurationField
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'.

Specified by:
getDifferenceAsLong in class DurationField
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

getUnitMillis

public long getUnitMillis()
Description copied from class: DurationField
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.

Specified by:
getUnitMillis in class DurationField
Returns:
the unit size of this field, in milliseconds
See Also:
DurationField.isPrecise()


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