Immutable representation of a time span as defined in the W3C XML Schema 1.0 specification.
A Duration object represents a period of Gregorian time, which consists of six fields (years, months, days, hours, minutes, and seconds) plus a sign (+/-) field.
The first five fields have non-negative (>=0) integers or null (which represents that the field is not set), and the seconds field has a non-negative decimal or null. A negative sign indicates a negative duration.
This class provides a number of methods that make it easy to use for the duration datatype of XML Schema 1.0 with the errata.
Duration objects only have partial order, where two values A and B maybe either:
For example, 30 days cannot be meaningfully compared to one month. The method implements this relationship.
See the
method for details about
the order relationship among Duration
objects.
This class provides a set of basic arithmetic operations, such as addition, subtraction and multiplication. Because durations don't have total order, an operation could fail for some combinations of operations. For example, you cannot subtract 15 days from 1 month. See the javadoc of those methods for detailed conditions where this could happen.
Also, division of a duration by a number is not provided because
the Duration
class can only deal with finite precision
decimal numbers. For example, one cannot represent 1 sec divided by 3.
However, you could substitute a division by 3 with multiplying by numbers such as 0.3 or 0.333.
Because some operations of Duration
rely on Calendar
even though Duration
can hold very large or very small values,
some of the methods may not work correctly on such Duration
s.
The impacted methods document their dependency on Calendar
.
Computes a new duration whose value is this+rhs
.
For example,
"1 day" + "-3 days" = "-2 days" "1 year" + "1 day" = "1 year and 1 day" "-(1 hour,50 minutes)" + "-20 minutes" = "-(1 hours,70 minutes)" "15 hours" + "-3 days" = "-(2 days,9 hours)" "1 year" + "-1 day" = IllegalStateException
Since there's no way to meaningfully subtract 1 day from 1 month, there are cases where the operation fails in IllegalStateException .
Formally, the computation is defined as follows.
Firstly, we can assume that two Duration
s to be added
are both positive without losing generality (i.e.,
(-X)+Y=Y-X
, X+(-Y)=X-Y
,
(-X)+(-Y)=-(X+Y)
)
Addition of two positive Duration
s are simply defined as
field by field addition where missing fields are treated as 0.
A field of the resulting Duration
will be unset if and
only if respective fields of two input Duration
s are unset.
Note that lhs.add(rhs)
will be always successful if
lhs.signum()*rhs.signum()!=-1
or both of them are
normalized.
Calls in the order of YEARS, MONTHS, DAYS, HOURS, MINUTES, SECONDS, and MILLISECONDS if those fields are present. Because the Calendar class uses int to hold values, there are cases where this method won't work correctly (for example if values of fields exceed the range of int.)
Also, since this duration class is a Gregorian duration, this method will not work correctly if the given Calendar object is based on some other calendar systems.
Any fractional parts of this Duration
object
beyond milliseconds will be simply ignored. For example, if
this duration is "P1.23456S", then 1 is added to SECONDS,
234 is added to MILLISECONDS, and the rest will be unused.
Note that because
is using
int, Duration
with values beyond the
range of int in its fields
will cause overflow/underflow to the given Calendar
.
provides the same
basic operation as this method while avoiding
the overflow/underflow issues.
The given date is first converted into a java.util.GregorianCalendar , then the duration is added exactly like the method.
The updated time instant is then converted back into a Date object and used to update the given Date object.
This somewhat redundant computation is necessary to unambiguously determine the duration of months and years.
Partial order relation comparison with this Duration
instance.
Comparison result must be in accordance with W3C XML Schema 1.0 Part 2, Section 3.2.7.6.2, Order relation on duration.
Return:
Duration
is shorter than duration
parameterDuration
is equal to duration
parameterDuration
is longer than duration
parameterChecks if this duration object has the same duration
as another Duration
object.
For example, "P1D" (1 day) is equal to "PT24H" (24 hours).
Duration X is equal to Y if and only if time instant t+X and t+Y are the same for all the test time instants specified in the section 3.2.6.2 of the XML Schema 1.0 specification.
Note that there are cases where two Duration
s are
"incomparable" to each other, like one month and 30 days.
For example,
!new Duration("P1M").isShorterThan(new Duration("P30D")) !new Duration("P1M").isLongerThan(new Duration("P30D")) !new Duration("P1M").equals(new Duration("P30D"))
Returns the length of the duration in milli-seconds.
If the seconds field carries more digits than milli-second order,
those will be simply discarded (or in other words, rounded to zero.)
For example, for any Calendar value x
,
new Duration("PT10.00099S").getTimeInMills(x) == 10000
.new Duration("-PT10.00099S").getTimeInMills(x) == -10000
.
Note that this method uses the
method,
which may work incorrectly with Duration
objects with
very large values in its fields. See the
method for details.
Returns the length of the duration in milli-seconds.
If the seconds field carries more digits than milli-second order,
those will be simply discarded (or in other words, rounded to zero.)
For example, for any Date
value x
,
new Duration("PT10.00099S").getTimeInMills(x) == 10000
.new Duration("-PT10.00099S").getTimeInMills(x) == -10000
.
Note that this method uses the
method,
which may work incorrectly with Duration
objects with
very large values in its fields. See the
method for details.
Return the name of the XML Schema date/time type that this instance
maps to. Type is computed based on fields that are set,
i.e.
== true
.
Required fields for XML Schema 1.0 Date/Time Datatypes. (timezone is optional for all date/time datatypes) |
||||||
---|---|---|---|---|---|---|
Datatype | year | month | day | hour | minute | second |
DatatypeConstants#DURATION | X | X | X | X | X | X |
DatatypeConstants#DURATION_DAYTIME | X | X | X | X | ||
DatatypeConstants#DURATION_YEARMONTH | X | X |
Get the years value of this Duration
as an int
or 0
if not present.
getYears()
is a convenience method for
getField(DatatypeConstants.YEARS)
.
As the return value is an int
, an incorrect value will be returned for Duration
s
with years that go beyond the range of an int
.
Use getField(DatatypeConstants.YEARS)
to avoid possible loss of precision.
Checks if this duration object is strictly longer than
another Duration
object.
Duration X is "longer" than Y if and only if X>Y as defined in the section 3.2.6.2 of the XML Schema 1.0 specification.
For example, "P1D" (one day) > "PT12H" (12 hours) and "P2Y" (two years) > "P23M" (23 months).
Checks if this duration object is strictly shorter than
another Duration
object.
factor
times
longer than the value of this duration.
For example,
"P1M" (1 month) * "12" = "P12M" (12 months) "PT1M" (1 min) * "0.3" = "PT18S" (18 seconds) "P1M" (1 month) * "1.5" = IllegalStateException
Since the Duration
class is immutable, this method
doesn't change the value of this object. It simply computes
a new Duration object and returns it.
The operation will be performed field by field with the precision of BigDecimal . Since all the fields except seconds are restricted to hold integers, any fraction produced by the computation will be carried down toward the next lower unit. For example, if you multiply "P1D" (1 day) with "0.5", then it will be 0.5 day, which will be carried down to "PT12H" (12 hours). When fractions of month cannot be meaningfully carried down to days, or year to months, this will cause an IllegalStateException to be thrown. For example if you multiple one month by 0.5.
To avoid IllegalStateException , use the method to remove the years and months fields.
Computes a new duration whose value is factor
times
longer than the value of this duration.
This method is provided for the convenience. It is functionally equivalent to the following code:
multiply(new BigDecimal(String.valueOf(factor)))
Duration
object whose
value is -this
.
Since the Duration
class is immutable, this method
doesn't change the value of this object. It simply computes
a new Duration object and returns it.
Converts the years and months fields into the days field by using a specific time instant as the reference point.
For example, duration of one month normalizes to 31 days given the start time instance "July 8th 2003, 17:40:32".
Formally, the computation is done as follows:
Note that since the Calendar class uses int
to
hold the value of year and month, this method may produce
an unexpected result if this duration object holds
a very large value in the years or months fields.
wait
methods.
The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
synchronized
statement
that synchronizes on the object.
Class,
by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
wait
methods.
The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify
method for a
description of the ways in which a thread can become the owner of
a monitor.
Computes a new duration whose value is this-rhs
.
For example:
"1 day" - "-3 days" = "4 days" "1 year" - "1 day" = IllegalStateException "-(1 hour,50 minutes)" - "-20 minutes" = "-(1hours,30 minutes)" "15 hours" - "-3 days" = "3 days and 15 hours" "1 year" - "-1 day" = "1 year and 1 day"
Since there's no way to meaningfully subtract 1 day from 1 month, there are cases where the operation fails in IllegalStateException .
Formally the computation is defined as follows.
First, we can assume that two Duration
s are both positive
without losing generality. (i.e.,
(-X)-Y=-(X+Y)
, X-(-Y)=X+Y
,
(-X)-(-Y)=-(X-Y)
)
Then two durations are subtracted field by field. If the sign of any non-zero field F is different from the sign of the most significant field, 1 (if F is negative) or -1 (otherwise) will be borrowed from the next bigger unit of F.
This process is repeated until all the non-zero fields have the same sign.
If a borrow occurs in the days field (in other words, if the computation needs to borrow 1 or -1 month to compensate days), then the computation fails by throwing an IllegalStateException .
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify
method or the
notifyAll
method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) { while (<condition does not hold>) obj.wait(); ... // Perform action appropriate to condition }This method should only be called by a thread that is the owner of this object's monitor. See the
notify
method for a
description of the ways in which a thread can become the owner of
a monitor.The current thread must own this object's monitor.
This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:
A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:
synchronized (obj) { while (<condition does not hold>) obj.wait(timeout); ... // Perform action appropriate to condition }(For more information on this topic, see Section 3.2.3 in Doug Lea's "Concurrent Programming in Java (Second Edition)" (Addison-Wesley, 2000), or Item 50 in Joshua Bloch's "Effective Java Programming Language Guide" (Addison-Wesley, 2001).
If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.
Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify
method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is similar to the wait
method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:
notify
method
or the notifyAll
method.
timeout
milliseconds plus nanos
nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) { while (<condition does not hold>) obj.wait(timeout, nanos); ... // Perform action appropriate to condition }This method should only be called by a thread that is the owner of this object's monitor. See the
notify
method for a
description of the ways in which a thread can become the owner of
a monitor.