net.time4j.engine

Interface UnitRule<T>

Type Parameters:

T - generic type of time context compatible to TimePoint

public interface UnitRule<T>

Represents a rule for the addition or subtraction associated with a time unit.

A unit rule will usually be registered together with an unit for a TimeAxis, during loading of the concrete TimePoint-class. For every time axis and every time unit there is exactly one rule instance. Implementations must be always immutable.

Author:

Meno Hochschild

Method Summary

Modifier and Type	Method and Description
T	addTo(T timepoint, long amount) Adds given amount to a time point in the context of an associated time unit.
long	between(T start, T end) Queries how many units are between given time points.

Method Detail

addTo

T addTo(T timepoint,
        long amount)

Adds given amount to a time point in the context of an associated time unit.

This method is called by the plus()- and minus()-methods in the class TimePoint. If not specified otherwise then a possible range overflow will be resolved such that the last valid time point is choosen. For example the addition of one month to date of 31th of may will yield June, 30th.

Parameters:

timepoint - time point

amount - count of units to be added to

Returns:

result of addition as changed copy, given time point remains unaffected

Throws:

ArithmeticException - in case of numerical overflow

See Also:

TimePoint.plus(long, U), TimePoint.minus(long, U)

between

long between(T start,
             T end)

Queries how many units are between given time points.

This method is called by TimePoint.until(T, U). The expression start.until(end, unit) corresponds to ruleForUnit.between(start, end). Only full units will be counted. A possible remainder of subtraction will always be truncated.

Parameters:

start - start time point

end - end time point

Returns:

difference in units (negative if end is before start)

Throws:

ArithmeticException - in case of numerical overflow

See Also:

TimePoint.until(T, U)