JarCastingJava Uuid Generator (JUG)
JUG is a set of Java classes for working with UUIDs: generating UUIDs using any of standard methods, outputting efficiently, sorting and so on. It generates UUIDs according to the UUID specification (RFC-4122) (also see Wikipedia UUID page for more explanation)
JUG was written by Tatu Saloranta ([email protected]) originally in 2002 and has been updated over years. In addition, many other individuals have helped fix bugs and implement new features: please see release-notes/CREDITS for the complete list.
JUG is licensed under Apache License 2.0.
Status
Usage
JUG can be used as a command-line tool (via class 'com.fasterxml.uuid.Jug`), or as a pluggable component.
Via Maven
Maven coordinates are:
<dependency>
<groupId>com.fasterxml.uuid</groupId>
<artifactId>java-uuid-generator</artifactId>
<version>4.0</version>
</dependency>
Dependencies
The only dependency for JUG is the logging library:
- For versions up to 3.x,
log4jis used, optionally (runtime dependency) - For versions 4.x and up,
slf4jAPI is used: logging implementation to be provided by calling application
JDK9+ module info
Since version 3.2.0, JUG defines JDK9+ compatible module-info.class, with module name of com.fasterxml.uuid.
Downloads
For direct downloads, check out Project Wiki.
Using JUG
Generation itself is done by first selecting a kind of generator to use, and then calling its generate() method, for example:
UUID uuid = Generators.randomBasedGenerator().generate();
UUID uuid = Generators.timeBasedGenerator().generate();
If you want customize generators, you may also just want to hold on to generator instance, for example:
TimeBasedGenerator gen = Generators.timeBasedGenerator(EthernetAddress.fromInterface());
UUID uuid = gen.generate();
UUID anotherUuid = gen.generate();
Generators are fully thread-safe, so a single instance may be shared among multiple threads.
JavaDocs for project can be found from Project Wiki.
Compatibility
JUG versions 3.1 and later require JDK 1.6 to work, mostly to be able to access local Ethernet MAC address. Earlier versions (3.0 and before) worked on 1.4 (which introduced java.util.UUID).
Known Issues
JDK's java.util.UUID has flawed implementation of compareTo(), which uses naive comparison of 64-bit values. This does NOT work as expected, given that underlying content is for all purposes unsigned. For example two UUIDs:
7f905a0b-bb6e-11e3-9e8f-000000000000
8028f08c-bb6e-11e3-9e8f-000000000000
would be ordered with second one first, due to sign extension (second value is considered to be negative, and hence "smaller").
Because of this, you should always use external comparator, such as com.fasterxml.uuid.UUIDComparator, which implements expected sorting order that is simple unsigned sorting, which is also same as lexicographic (alphabetic) sorting of UUIDs (when assuming uniform capitalization).
Enterprise support
Available as part of the Tidelift Subscription.
The maintainers of java-uuid-generator and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source dependencies you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact dependencies you use. Learn more.
Contributing
For simple bug reports and fixes, and feature requests, please simply use projects Issue Tracker, with exception of security-related issues for which we recommend filing Tidelift security contact (NOTE: you do NOT have to be a subscriber to do this).
Alternative JVM UUID generators
There are many other publicly available UUID generators. For example:
- Apache Commons IO has UUID generator
- eaio-uuid
- JDK has included
java.util.UUIDsince 1.4, but omits generation methods (esp. time/location based ones), has sub-standard performance for many operations and implements comparison in useless way - ohannburkard.de UUID generator
Note that although some packages claim to be faster than others, it is not clear whether:
- Claims have been properly verified (or, if they have, can be independently verified), AND
- It is not likely that performance differences truly matter: JUG, for example, can generate a millions of UUID per second per core (sometimes hitting the theoretical limit of 10 million per second) -- and it seems unlikely that generation will be bottleneck for about any use case
so it is often best to choose based on stability of packages and API.