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java.lang.Object com.datastax.driver.core.utils.UUIDs
public final class UUIDs
Utility methods to work with UUID and most specifically with time-based ones (version 1).
Constructor Summary | |
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UUIDs()
|
Method Summary | |
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static UUID |
endOf(long timestamp)
Creates a "fake" time-based UUID that sorts as the biggest possible version 1 UUID generated at the provided timestamp. |
static UUID |
random()
Creates a new random (version 4) UUID. |
static UUID |
startOf(long timestamp)
Creates a "fake" time-based UUID that sorts as the smallest possible version 1 UUID generated at the provided timestamp. |
static UUID |
timeBased()
Creates a new time-based (version 1) UUID. |
static long |
unixTimestamp(UUID uuid)
Return the unix timestamp contained by the provided time-based UUID. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public UUIDs()
Method Detail |
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public static UUID random()
This method is just a convenience for UUID.randomUUID()
.
public static UUID timeBased()
UUID generated by this method are suitable for use with the
timeuuid
Cassandra type. In particular the generated UUID
includes the timestamp of its generation.
public static UUID startOf(long timestamp)
Such created UUID are useful in queries to select a time range of a
timeuuid
column.
The UUID created by this method are not unique and as such are not suitable for anything else than querying a specific time range. In particular, you should not insert such UUID.
Also, the timestamp to provide as parameter must be a unix timestamp (as
returned by System.currentTimeMillis()
or Date.getTime()
),
not a UUID 100-nanoseconds intervals since 15 October 1582. In other
words, given a UUID uuid
, you should never do
startOf(uuid.timestamp())
but rather
startOf(unixTimestamp(uuid.timestamp()))
.
Lastly, please note that Cassandra's timeuuid sorting is not compatible
with UUID.compareTo(java.util.UUID)
and hence the UUID created by this method
are not necesssary lower bound for that latter method.
timestamp
- the unix timestamp for which the created UUID must be a
lower bound.
timestamp
.public static UUID endOf(long timestamp)
Such created UUID are useful in queries to select a time range of a
timeuuid
column.
The UUID created by this method are not unique and as such are not suitable for anything else than querying a specific time range. In particular, you should not insert such UUID.
Also, the timestamp to provide as parameter must be a unix timestamp (as
returned by System.currentTimeMillis()
or Date.getTime()
),
not a UUID 100-nanoseconds intervals since 15 October 1582. In other
words, given a UUID uuid
, you should never do
startOf(uuid.timestamp())
but rather
startOf(unixTimestamp(uuid.timestamp()))
.
Lastly, please note that Cassandra's timeuuid sorting is not compatible
with UUID.compareTo(java.util.UUID)
and hence the UUID created by this method
are not necesssary upper bound for that latter method.
timestamp
- the unix timestamp for which the created UUID must be an
upper bound.
timestamp
.public static long unixTimestamp(UUID uuid)
This method is not equivalent to uuid.timestamp()
. More
precisely, a version 1 UUID stores a timestamp that represents the
number of 100-nanoseconds intervals since midnight, 15 October 1582 and
that is what uuid.timestamp()
returns. This method however
converts that timestamp to the equivalent unix timestamp in
milliseconds, i.e. a timestamp representing a number of milliseconds
since midnight, January 1, 1970 UTC. In particular the timestamps
returned by this method are comparable to the timestamp returned by
System.currentTimeMillis()
, Date.getTime()
, etc.
uuid
- the UUID to return the timestamp of.
uuid
.
IllegalArgumentException
- if uuid
is not a version 1 UUID.
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