![]() Is there a better way of generating UUIDs? Answer1 u = (u | 0x80) & 0xBF // what's the purpose ? u = (u | 0x40) & 0x4F // what's the purpose ? These If it is a real UUID, why is it a UUID, and what is the purpose of the code that modifies the value of u and u. Answer1 I tested it for ( ) u = (u | 0x80) & 0xBF // what does this do? u = (u | 0x40) & 0x4F // what does this do? return hex.EncodeToString(u) It returns a string with a length of 32, but I don't think it is a valid UUID. I wanted to see if anyone else has ran into this limitation with Java's built-in UUID generation capability in either Java 6 or Java 7 applications. He points to this article to help back up his results. One of our testers is claiming up to 350ms to generate UUIDs based upon his own profiling, but I have not yet been able to replicate his results. Performance of Random UUID generation with Java 7 or Java 6 Question I have a web based Java application that generates random UUIDs for session information.Answer2 You can try RandomStringUtils class from mons: import 3.RandomStringUtils final int SHORT_ID_LENGTH = 8 // this is the case with MAC, DCE and MD5 UUIDs). Also be careful with generating longer UUIDs and substring-ing them, since some parts of the ID may contain fixed bytes (e.g. But of course, you can generate 8-character long unique strings (see the other answers). ![]() I want to generate 8-character only UUIDs, is it possible? Answer1 It is not possible since a UUID is a 16-byte number per definition. Generating 8-character only UUIDs Question UUID libraries generate 32-character UUIDs.This source code is published under the Apache 2 license. UUIDGen class source code, part of the Apache Cassandra project.Java Uuid Generator (JUG) originally by Tatu Saloranta.UUID Creator providing Versions 1, 2, 3, 4, 5, and 6.So I asked on the sister site, Software Recommendations Stack Exchange, the question Library to generate Version 1 UUIDs to be called from Java.Īnd here is a condensed list of the implementations mentioned in other Answers here and elsewhere that seem to still be actively supported. 3rd party implementationsĪs seen on the other Answers, there are 3rd-party implementations of Version 1 UUIDs available.Īsking for library recommendations is off-topic here on Stack Overflow. Presumably this is because of the security and privacy concerns from potentially divulging your MAC address and the moment of creation. Java omits Version 1Īs you have noticed, no implementation of Version 1 UUID is required by the Java specifications. The "time" part is a 60-bit timestamp, being the number of 100-nanosecond intervals since midnight 15 October 1582 Coordinated Universal Time (UTC). The "space" part is the MAC address taken from the networking port of the computer to uniquely identify where the id was generated (nearly unique, there have been some infamous screw-ups in assigning MAC addresses by the networking hardware manufacturers). Version 1 UUIDs actually represent a point in space and in time. Version 1 represents a point in space and time
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