com.ibm.icu.util
public final class UniversalTimeScale extends Object
averageTime = (time1 + time2)/2
, there will be overflow even with dates
beginning in 2004. Moreover, even if these problems don't occur, there is the issue of
conversion back and forth between different systems.
Binary datetimes differ in a number of ways: the datatype, the unit, and the epoch (origin). We refer to these as time scales.
ICU implements a universal time scale that is similar to the .NET framework's System.DateTime. The universal time scale is a 64-bit integer that holds ticks since midnight, January 1st, 0001. (One tick is 100 nanoseconds.) Negative values are supported. This has enough range to guarantee that calculations involving dates around the present are safe.
The universal time scale always measures time according to the proleptic Gregorian calendar. That is, the Gregorian calendar's leap year rules are used for all times, even before 1582 when it was introduced. (This is different from the default ICU calendar which switches from the Julian to the Gregorian calendar in 1582. See GregorianCalendar.setGregorianChange() and ucal_setGregorianChange().)
ICU provides conversion functions to and from all other major time scales, allowing datetimes in any time scale to be converted to the universal time scale, safely manipulated, and converted back to any other datetime time scale.For more details and background, see the Universal Time Scale chapter in the ICU User Guide.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
Field Summary | |
---|---|
static int | DB2_TIME
Used in DB2. |
static int | DOTNET_DATE_TIME
Used in the .NET framework's System.DateTime structure.
|
static int | EPOCH_OFFSET_MINUS_1_VALUE
The constant used to select the epoch offset minus one value
for a time scale.
|
static int | EPOCH_OFFSET_PLUS_1_VALUE
The constant used to select the epoch plus one value
for a time scale.
|
static int | EPOCH_OFFSET_VALUE
The constant used to select the epoch offset value
for a time scale.
|
static int | EXCEL_TIME
Used in Excel. |
static int | FROM_MAX_VALUE
The constant used to select the maximum from value
for a time scale.
|
static int | FROM_MIN_VALUE
The constant used to select the minimum from value
for a time scale.
|
static int | ICU4C_TIME
Used in the ICU4C. |
static int | JAVA_TIME
Used in the JDK. |
static int | MAC_OLD_TIME
Used in older Macintosh systems. |
static int | MAC_TIME
Used in the JDK. |
static int | MAX_ROUND_VALUE
The constant used to select the maximum safe rounding value
for a time scale.
|
static int | MAX_SCALE
This is the first unused time scale value.
|
static int | MAX_SCALE_VALUE
The number of time scale values.
|
static int | MIN_ROUND_VALUE
The constant used to select the minimum safe rounding value
for a time scale.
|
static int | TO_MAX_VALUE
The constant used to select the maximum to value
for a time scale.
|
static int | TO_MIN_VALUE
The constant used to select the minimum to value
for a time scale.
|
static int | UNITS_ROUND_VALUE
The constant used to select the units round value
for a time scale.
|
static int | UNITS_VALUE
The constant used to select the units value
for a time scale.
|
static int | UNIX_TIME
Used in Unix systems. |
static int | WINDOWS_FILE_TIME
Used in Windows for file times. |
Method Summary | |
---|---|
static BigDecimal | bigDecimalFrom(double otherTime, int timeScale)
Convert a double datetime from the given time scale to the universal time scale.
|
static BigDecimal | bigDecimalFrom(long otherTime, int timeScale)
Convert a long datetime from the given time scale to the universal time scale.
|
static BigDecimal | bigDecimalFrom(BigDecimal otherTime, int timeScale)
Convert a BigDecimal datetime from the given time scale to the universal time scale.
|
static long | from(long otherTime, int timeScale)
Convert a long datetime from the given time scale to the universal time scale.
|
static long | getTimeScaleValue(int scale, int value)
Get a value associated with a particular time scale.
|
static BigDecimal | toBigDecimal(long universalTime, int timeScale)
Convert a datetime from the universal time scale to a BigDecimal in the given time scale.
|
static BigDecimal | toBigDecimal(BigDecimal universalTime, int timeScale)
Convert a datetime from the universal time scale to a BigDecimal in the given time scale.
|
static BigDecimal | toBigDecimalTrunc(BigDecimal universalTime, int timeScale)
Convert a time in the Universal Time Scale into another time
scale. |
static long | toLong(long universalTime, int timeScale)
Convert a datetime from the universal time scale stored as a BigDecimal to a
long in the given time scale.
|
?unknown?
. Value
is days since December 31, 1899.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
System.DateTime
structure.
Data is a long
. Value is ticks (1 tick == 100 nanoseconds) since January 1, 0001.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
Deprecated: This API is ICU internal only.
The constant used to select the epoch offset minus one value for a time scale. NOTE: This is an internal value. DO NOT USE IT. May not actually be equal to the epoch offset value minus one.See Also: UniversalTimeScale
UNKNOWN:
See Also: UniversalTimeScale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
See Also: UniversalTimeScale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
?unknown?
. Value
is days since December 31, 1899.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
See Also: UniversalTimeScale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
See Also: UniversalTimeScale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
double
. Value
is milliseconds since January 1, 1970.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
long
. Value
is milliseconds since January 1, 1970.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
int
. Value
is seconds since January 1, 1904.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
double
. Value
is milliseconds since January 1, 2001.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
Deprecated: This API is ICU internal only.
The constant used to select the maximum safe rounding value for a time scale. NOTE: This is an internal value. DO NOT USE IT.See Also: UniversalTimeScale
UNKNOWN:
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
Deprecated: This API is ICU internal only.
The number of time scale values. NOTE: This is an internal value. DO NOT USE IT.See Also: UniversalTimeScale
UNKNOWN:
Deprecated: This API is ICU internal only.
The constant used to select the minimum safe rounding value for a time scale. NOTE: This is an internal value. DO NOT USE IT.See Also: UniversalTimeScale
UNKNOWN:
See Also: UniversalTimeScale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
See Also: UniversalTimeScale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
Deprecated: This API is ICU internal only.
The constant used to select the units round value for a time scale. NOTE: This is an internal value. DO NOT USE IT.See Also: UniversalTimeScale
UNKNOWN:
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
int
or a long
. Value
is seconds since January 1, 1970.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
long
. Value
is ticks (1 tick == 100 nanoseconds) since January 1, 1601.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
double
datetime from the given time scale to the universal time scale.
All calculations are done using BigDecimal
to guarantee that the value
does not go out of range.
Parameters: otherTime The double
datetime timeScale The time scale to convert from
Returns: The datetime converted to the universal time scale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
long
datetime from the given time scale to the universal time scale.
All calculations are done using BigDecimal
to guarantee that the value
does not go out of range.
Parameters: otherTime The long
datetime timeScale The time scale to convert from
Returns: The datetime converted to the universal time scale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
BigDecimal
datetime from the given time scale to the universal time scale.
All calculations are done using BigDecimal
to guarantee that the value
does not go out of range.
Parameters: otherTime The BigDecimal
datetime timeScale The time scale to convert from
Returns: The datetime converted to the universal time scale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
long
datetime from the given time scale to the universal time scale.
Parameters: otherTime The long
datetime timeScale The time scale to convert from
Returns: The datetime converted to the universal time scale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
Parameters: scale - the time scale value - a constant representing the value to get
Returns: - the value.
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
BigDecimal
in the given time scale.
Parameters: universalTime The datetime in the universal time scale timeScale The time scale to convert to
Returns: The datetime converted to the given time scale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
BigDecimal
in the given time scale.
Parameters: universalTime The datetime in the universal time scale timeScale The time scale to convert to
Returns: The datetime converted to the given time scale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.
Deprecated: This API is ICU internal only.
Convert a time in the Universal Time Scale into another time scale. The division used to do the conversion rounds down. NOTE: This is an internal routine used by the tool that generates the to and from limits. Use it at your own risk.Parameters: universalTime the time in the Universal Time scale timeScale the time scale to convert to
Returns: the time in the given time scale
UNKNOWN:
BigDecimal
to a
long
in the given time scale.
Since this calculation requires a divide, we must round. The straight forward
way to round by adding half of the divisor will push the sum out of range for values
within have the divisor of the limits of the precision of a long
. To get around this, we do
the rounding like this:
(universalTime - units + units/2) / units + 1
(i.e. we subtract units first to guarantee that we'll still be in range when we
add units/2
. We then need to add one to the quotent to make up for the extra subtraction.
This simplifies to:
(universalTime - units/2) / units - 1
For negative values to round away from zero, we need to flip the signs:
(universalTime + units/2) / units + 1
Since we also need to subtract the epochOffset, we fold the +/- 1
into the offset value. (i.e. epochOffsetP1
, epochOffsetM1
.)
Parameters: universalTime The datetime in the universal time scale timeScale The time scale to convert to
Returns: The datetime converted to the given time scale
UNKNOWN: ICU 3.2 This API might change or be removed in a future release.