net.time4j.engine

Class AbstractMetric<U extends ChronoUnit,P extends AbstractDuration<U>>

java.lang.Object

net.time4j.engine.AbstractMetric<U,P>

Type Parameters:

U - generic type of time unit (ChronoUnit)

P - generic type of duration result

All Implemented Interfaces:

Comparator<U>, TimeMetric<U,P>

public abstract class AbstractMetric<U extends ChronoUnit,P extends AbstractDuration<U>>
extends Object
implements TimeMetric<U,P>, Comparator<U>

Represents a metric suitable for the default algorithm of Time4J.

If the starting time point is after the end time point then a duration computed with this metric will be negative. In this case the metric defined here will first toggle the time points to be compared and then compare all elements in the order of ascending precision. Elements which differ less than a full unit will cause an amount of 0 in related duration item. Convertible units will be consolidated in one step. Finally the representation of the duration will be normalized such that small units will be converted to larger units if possible.

Author:

Meno Hochschild

See Also:

AbstractDuration

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractMetric(boolean normalizing, Set<U> units) Creates a new default metric with given set of time units.
protected	AbstractMetric(boolean normalizing, U... units) Creates a new default metric with given array of time units.

Method Summary

Methods

Modifier and Type	Method and Description
<T extends TimePoint<? super U,T>> P	between(T start, T end) Computes the temporal distance between two time points.
int	compare(U u1, U u2) Compares time units by their length in descending order.
protected abstract P	createEmptyTimeSpan() Creates an empty time span.
protected abstract P	createTimeSpan(List<TimeSpan.Item<U>> items, boolean negative) Creates a time span with the given units and amounts.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.Comparator

equals

Constructor Detail

AbstractMetric

protected AbstractMetric(boolean normalizing,
              U... units)

Creates a new default metric with given array of time units.

The given time units can be in any arbitrary order, but internally the will be automatically sorted by their default estimated length.

Parameters:

normalizing - Is normalizing required that is shall amounts in small units be converted to bigger units?

units - time units to be used for calculating time span

Throws:

IllegalArgumentException - if any time unit is given more than once or if there is no time unit at all

AbstractMetric

protected AbstractMetric(boolean normalizing,
              Set<U> units)

Creates a new default metric with given set of time units.

The given time units can be in any arbitrary order, but internally the will be automatically sorted by their default estimated length.

Parameters:

normalizing - Is normalizing required that is shall amounts in small units be converted to bigger units?

units - time units to be used for calculating time span

Throws:

IllegalArgumentException - if there is not time unit at all

Method Detail

compare

public int compare(U u1,
          U u2)

Compares time units by their length in descending order.

Specified by:

compare in interface Comparator<U extends ChronoUnit>

Parameters:

u1 - first time unit

u2 - second time unit

Returns:

negative, zero or positive if u1 is greater, equal to or smaller than u2

between

public <T extends TimePoint<? super U,T>> P between(T start,
                                           T end)

Description copied from interface: TimeMetric

Computes the temporal distance between two time points.

Specified by:

between in interface TimeMetric<U extends ChronoUnit,P extends AbstractDuration<U>>

Type Parameters:

T - generic type of time point

Parameters:

start - first time point

end - second time point

Returns:

calculated time span between given time points, will be negative if start is after end

createEmptyTimeSpan

protected abstract P createEmptyTimeSpan()

Creates an empty time span.

Returns:

empty time span without any time units

See Also:

TimeSpan.isEmpty()

createTimeSpan

protected abstract P createTimeSpan(List<TimeSpan.Item<U>> items,
               boolean negative)

Creates a time span with the given units and amounts.

Parameters:

items - elements of time span

negative - sign of time span

Returns:

new time span