Duration

  • The javax.xml.datatype.Duration class in Java represents a time-based amount with fields for years, months, days, hours, minutes, and seconds.

  • It supports operations like addition, subtraction, multiplication, comparison, and normalization, but division is not supported due to finite precision.

  • Durations have a partial order, meaning some comparisons may be indeterminate, such as comparing 30 days to 1 month.

  • The Duration class adheres to the W3C XML Schema 1.0 specification and provides methods to interact with Calendar and Date objects.

  • Certain operations might throw exceptions like IllegalStateException if durations are incompatible or if the resulting duration would be meaningless (e.g., subtracting 1 day from 1 month).
public abstract class Duration extends Object

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.

Order relationship

Duration objects only have partial order, where two values A and B maybe either:

  1. A<B (A is shorter than B)
  2. A>B (A is longer than B)
  3. A==B (A and B are of the same duration)
  4. A<>B (Comparison between A and B is indeterminate)

For example, 30 days cannot be meaningfully compared to one month. The compare(Duration) method implements this relationship.

See the isLongerThan(Duration) method for details about the order relationship among Duration objects.

Operations over Duration

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.

Range of allowed values

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 Durations. The impacted methods document their dependency on Calendar.

See Also

Public Constructor Summary

Duration()

Public Method Summary

abstract Duration
add(Duration rhs)

Computes a new duration whose value is this+rhs.
abstract void
addTo(Calendar calendar)
Adds this duration to a Calendar object.
void
addTo(Date date)
Adds this duration to a Date object.
abstract int
compare(Duration duration)

Partial order relation comparison with this Duration instance.
boolean
equals(Object duration)

Checks if this duration object has the same duration as another Duration object.
int
getDays()
Obtains the value of the DAYS field as an integer value, or 0 if not present.
abstract Number
getField(DatatypeConstants.Field field)
Gets the value of a field.
int
getHours()
Obtains the value of the HOURS field as an integer value, or 0 if not present.
int
getMinutes()
Obtains the value of the MINUTES field as an integer value, or 0 if not present.
int
getMonths()
Obtains the value of the MONTHS field as an integer value, or 0 if not present.
int
getSeconds()
Obtains the value of the SECONDS field as an integer value, or 0 if not present.
abstract int
getSign()
Returns the sign of this duration in -1,0, or 1.
long
getTimeInMillis(Calendar startInstant)

Returns the length of the duration in milliseconds.
long
getTimeInMillis(Date startInstant)

Returns the length of the duration in milliseconds.
QName
getXMLSchemaType()

Return the name of the XML Schema date/time type that this instance maps to.
int
getYears()

Get the years value of this Duration as an int or 0 if not present.
abstract int
hashCode()
Returns a hash code consistent with the definition of the equals method.
boolean
isLongerThan(Duration duration)

Checks if this duration object is strictly longer than another Duration object.
abstract boolean
isSet(DatatypeConstants.Field field)
Checks if a field is set.
boolean
isShorterThan(Duration duration)

Checks if this duration object is strictly shorter than another Duration object.
Duration
multiply(int factor)

Computes a new duration whose value is factor times longer than the value of this duration.
abstract Duration
multiply(BigDecimal factor)
Computes a new duration whose value is factor times longer than the value of this duration.
abstract Duration
negate()
Returns a new Duration object whose value is -this.
abstract Duration
normalizeWith(Calendar startTimeInstant)

Converts the years and months fields into the days field by using a specific time instant as the reference point.
Duration
subtract(Duration rhs)

Computes a new duration whose value is this-rhs.
String
toString()

Returns a String representation of this Duration Object.

Inherited Method Summary

Public Constructors

public Duration ()

Public Methods

public abstract Duration add (Duration rhs)

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 Durations 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 Durations 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 Durations are unset.

Note that lhs.add(rhs) will be always successful if lhs.signum()*rhs.signum()!=-1 or both of them are normalized.

Parameters
rhs Duration to add to this Duration
Returns
  • non-null valid Duration object.
Throws
NullPointerException If the rhs parameter is null.
IllegalStateException If two durations cannot be meaningfully added. For example, adding negative one day to one month causes this exception.
See Also

public abstract void addTo (Calendar calendar)

Adds this duration to a Calendar object.

Calls Calendar.add(int, int) 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 Calendar.add(int, int) is using int, Duration with values beyond the range of int in its fields will cause overflow/underflow to the given Calendar. XMLGregorianCalendar.add(Duration) provides the same basic operation as this method while avoiding the overflow/underflow issues.

Parameters
calendar A calendar object whose value will be modified.
Throws
NullPointerException if the calendar parameter is null.

public void addTo (Date date)

Adds this duration to a Date object.

The given date is first converted into a GregorianCalendar, then the duration is added exactly like the addTo(Calendar) 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.

Parameters
date A date object whose value will be modified.
Throws
NullPointerException if the date parameter is null.

public abstract int compare (Duration duration)

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:

Parameters
duration to compare
Returns
Throws
UnsupportedOperationException If the underlying implementation cannot reasonably process the request, e.g. W3C XML Schema allows for arbitrarily large/small/precise values, the request may be beyond the implementations capability.
NullPointerException if duration is null.
See Also

public boolean equals (Object duration)

Checks 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 Durations 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"))

Parameters
duration A non-null valid Duration object.
Returns
  • true if this duration is the same length as duration. false if duration is not a Duration object, is null, or its length is different from this duration.
Throws
UnsupportedOperationException If the underlying implementation cannot reasonably process the request, e.g. W3C XML Schema allows for arbitrarily large/small/precise values, the request may be beyond the implementations capability.
See Also

public int getDays ()

Obtains the value of the DAYS field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the DAYS field.

Returns
  • Days of this Duration.

public abstract Number getField (DatatypeConstants.Field field)

Gets the value of a field. Fields of a duration object may contain arbitrary large value. Therefore this method is designed to return a Number object. In case of YEARS, MONTHS, DAYS, HOURS, and MINUTES, the returned number will be a non-negative integer. In case of seconds, the returned number may be a non-negative decimal value.

Parameters
field one of the six Field constants (YEARS,MONTHS,DAYS,HOURS, MINUTES, or SECONDS.)
Returns
  • If the specified field is present, this method returns a non-null non-negative Number object that represents its value. If it is not present, return null. For YEARS, MONTHS, DAYS, HOURS, and MINUTES, this method returns a BigInteger object. For SECONDS, this method returns a BigDecimal.
Throws
NullPointerException If the field is null.

public int getHours ()

Obtains the value of the HOURS field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the HOURS field.

Returns
  • Hours of this Duration.

public int getMinutes ()

Obtains the value of the MINUTES field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the MINUTES field.

Returns
  • Minutes of this Duration.

public int getMonths ()

Obtains the value of the MONTHS field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the MONTHS field.

Returns
  • Months of this Duration.

public int getSeconds ()

Obtains the value of the SECONDS field as an integer value, or 0 if not present. This method works just like getYears() except that this method works on the SECONDS field.

Returns
  • seconds in the integer value. The fraction of seconds will be discarded (for example, if the actual value is 2.5, this method returns 2)

public abstract int getSign ()

Returns the sign of this duration in -1,0, or 1.

Returns
  • -1 if this duration is negative, 0 if the duration is zero, and 1 if the duration is positive.

public long getTimeInMillis (Calendar startInstant)

Returns the length of the duration in milliseconds.

If the seconds field carries more digits than millisecond 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 addTo(Calendar) method, which may work incorrectly with Duration objects with very large values in its fields. See the addTo(Calendar) method for details.

Parameters
startInstant The length of a month/year varies. The startInstant is used to disambiguate this variance. Specifically, this method returns the difference between startInstant and startInstant+duration
Returns
  • milliseconds between startInstant and startInstant plus this Duration
Throws
NullPointerException if startInstant parameter is null.

public long getTimeInMillis (Date startInstant)

Returns the length of the duration in milliseconds.

If the seconds field carries more digits than millisecond 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 addTo(Date) method, which may work incorrectly with Duration objects with very large values in its fields. See the addTo(Date) method for details.

Parameters
startInstant The length of a month/year varies. The startInstant is used to disambiguate this variance. Specifically, this method returns the difference between startInstant and startInstant+duration.
Returns
  • milliseconds between startInstant and startInstant plus this Duration
Throws
NullPointerException If the startInstant parameter is null.
See Also

public QName getXMLSchemaType ()

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. isSet(DatatypeConstants.Field) == 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

Returns
Throws
IllegalStateException If the combination of set fields does not match one of the XML Schema date/time datatypes.

public int getYears ()

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 Durations with years that go beyond the range of an int. Use getField(DatatypeConstants.YEARS) to avoid possible loss of precision.

Returns
  • If the years field is present, return its value as an int, else return 0.

public abstract int hashCode ()

Returns a hash code consistent with the definition of the equals method.

Returns
  • this object's hash code.
See Also

public boolean isLongerThan (Duration duration)

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).

Parameters
duration Duration to test this Duration against.
Returns
  • true if the duration represented by this object is longer than the given duration. false otherwise.
Throws
UnsupportedOperationException If the underlying implementation cannot reasonably process the request, e.g. W3C XML Schema allows for arbitrarily large/small/precise values, the request may be beyond the implementations capability.
NullPointerException If duration is null.
See Also

public abstract boolean isSet (DatatypeConstants.Field field)

Checks if a field is set. A field of a duration object may or may not be present. This method can be used to test if a field is present.

Parameters
field one of the six Field constants (YEARS,MONTHS,DAYS,HOURS, MINUTES, or SECONDS.)
Returns
  • true if the field is present. false if not.
Throws
NullPointerException If the field parameter is null.

public boolean isShorterThan (Duration duration)

Checks if this duration object is strictly shorter than another Duration object.

Parameters
duration Duration to test this Duration against.
Returns
  • true if duration parameter is shorter than this Duration, else false.
Throws
UnsupportedOperationException If the underlying implementation cannot reasonably process the request, e.g. W3C XML Schema allows for arbitrarily large/small/precise values, the request may be beyond the implementations capability.
NullPointerException if duration is null.
See Also

public Duration multiply (int factor)

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)))

Parameters
factor Factor times longer of new Duration to create.
Returns
  • New Duration that is factortimes longer than this Duration.
See Also

public abstract Duration multiply (BigDecimal factor)

Computes a new duration whose value is 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 normalizeWith(Calendar) method to remove the years and months fields.

Parameters
factor to multiply by
Returns
  • returns a non-null valid Duration object
Throws
IllegalStateException if operation produces fraction in the months field.
NullPointerException if the factor parameter is null.

public abstract Duration negate ()

Returns a new 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.

Returns
  • always return a non-null valid Duration object.

public abstract Duration normalizeWith (Calendar startTimeInstant)

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:

  1. the given Calendar object is cloned
  2. the years, months and days fields will be added to the Calendar object by using the Calendar.add(int, int) method
  3. the difference between the two Calendars in computed in milliseconds and converted to days, if a remainder occurs due to Daylight Savings Time, it is discarded
  4. the computed days, along with the hours, minutes and seconds fields of this duration object is used to construct a new Duration object.

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.

Parameters
startTimeInstant Calendar reference point.
Returns
  • Duration of years and months of this Duration as days.
Throws
NullPointerException If the startTimeInstant parameter is null.

public Duration subtract (Duration rhs)

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 Durations 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.

Parameters
rhs Duration to subtract from this Duration.
Returns
  • New Duration created from subtracting rhs from this Duration.
Throws
IllegalStateException If two durations cannot be meaningfully subtracted. For example, subtracting one day from one month causes this exception.
NullPointerException If the rhs parameter is null.
See Also

public String toString ()

Returns a String representation of this Duration Object.

The result is formatted according to the XML Schema 1.0 specification and can be always parsed back later into the equivalent Duration Object by DatatypeFactory.newDuration(String).

Formally, the following holds for any Duration Object x:

 new Duration(x.toString()).equals(x)

Returns
  • A non-null valid String representation of this Duration.