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fabiolimace committed May 11, 2024
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Expand Up @@ -7,7 +7,7 @@ This is a Java library for generating [Universally Unique Identifiers](https://e

The Internet standard [RFC 9562](https://www.rfc-editor.org/rfc/rfc9562) was published in May 2024, making RFC 4122 obsolete. This library is fully compliant with the new RFC, as it was developed following the evolution of the new Internet standard until its publication.

List of implemented UUID types:
List of implemented UUID subtypes:

* __UUID Version 1__: the Gregorian time-based UUID specified in RFC 9562;
* __UUID Version 2__: the DCE Security version, with embedded POSIX UIDs, specified in DCE 1.1;
Expand All @@ -21,19 +21,22 @@ This library solves some of the JDK's UUID issues:

| Problem | Solution |
|---------|----------|
| `UUID` can't generate Gregorian time-based UUIDs (UUIDv1). | Use [`UuidCreator.getTimeBased()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#getTimeBased()) or [`GUID.v1()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#v1()). |
| `UUID` can't generate SHA-1 UUIDs (UUIDv5). | Use [`UuidCreator.getNameBasedSha1()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#getNameBasedSha1(java.util.UUID,java.lang.String)) or [`GUID.v5()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#v5(com.github.f4b6a3.uuid.alt.GUID,java.lang.String)). |
| `UUID` has no validation method, which makes developers use `UUID.fromString()` or regular expression for validation. | Use [`UuidValidator`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/util/UuidValidator.html) or [`GUID.valid()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#valid(java.lang.String)). |
| `UUID.nameUUIDFromBytes()`, which generates MD5 UUIDs (UUIDv3), does not have a namespace parameter as required by the standard. | Use [`UuidCreator.getNameBasedMd5()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#getNameBasedMd5(java.util.UUID,java.lang.String)) or [`GUID.v3()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#v3(com.github.f4b6a3.uuid.alt.GUID,java.lang.String)). |
| `UUID` can't generate Gregorian time-based UUIDs (UUIDv1). | Use: <br> <ul><li> [`UuidCreator.getTimeBased()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#getTimeBased()); or </li><li> [`GUID.v1()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#v1()). </li></ul> |
| `UUID` can't generate SHA-1 UUIDs (UUIDv5). | Use: <br> <ul><li>[`UuidCreator.getNameBasedSha1()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#getNameBasedSha1(java.util.UUID,java.lang.String)); or </li><li> [`GUID.v5()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#v5(com.github.f4b6a3.uuid.alt.GUID,java.lang.String)). </li></ul> |
| `UUID` has no validation method, which makes developers use `UUID.fromString()` or regular expression for validation. | Use: <br> <ul><li> [`UuidValidator.isValid()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/util/UuidValidator.html#isValid(java.lang.String)); or </li><li> [`GUID.valid()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#valid(java.lang.String)). </li></ul> |
| `UUID.nameUUIDFromBytes()`, which generates MD5 UUIDs (UUIDv3), does not have a namespace parameter as required by the standard. | Use: <br> <ul><li> [`UuidCreator.getNameBasedMd5()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#getNameBasedMd5(java.util.UUID,java.lang.String)); or </li><li> [`GUID.v3()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#v3(com.github.f4b6a3.uuid.alt.GUID,java.lang.String)). </li></ul> |
| Some methods such as `UUID.timestamp()` are strongly related to UUIDv1, even though it's impossible to generate UUIDv1. | Use [`UuidUtil`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/util/UuidUtil.html). |
| `UUID.randomUUID()` can be slow due to [lack of entropy](https://medium.com/@RamLakshmanan/java-uuid-generation-performance-impact-cec888b7d9b8) in the operating system. | Use [`UuidCreator.getRandomBasedFast()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#getRandomBasedFast()) or [`GUID.v4()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#v4()). However, keep in mind that both are not cryptographically secure. |
| `UUID.randomUUID()` can be slow due to [lack of entropy](https://medium.com/@RamLakshmanan/java-uuid-generation-performance-impact-cec888b7d9b8) in the operating system. | Use: <br> <ul><li> [`UuidCreator.getRandomBasedFast()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#getRandomBasedFast()); or </li><li> [`GUID.v4()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#v4()). </li></ul> <em>However, keep in mind that none of them are cryptographically secure.</em> |
| `UUID.compareTo()` [behaves unexpectedly](https://yoshiori.hatenablog.com/entry/2024/02/22/173322) due to signed `long` comparisons, causing non-alphabetical sorting. | Use [`UuidComparator`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/util/UuidComparator.html). |
| `UUID.fromString()` allows non-canonical strings like `0-0-0-0-0` as valid UUID strings. | Use [`UuidCreator.fromString()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#fromString(java.lang.String)) or [`new GUID()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#%3Cinit%3E(java.lang.String)). |
| `UUID.fromString()` allows non-canonical strings like `0-0-0-0-0` as valid UUID strings. | Use: <br> <ul><li> [`UuidCreator.fromString()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/UuidCreator.html#fromString(java.lang.String)); or </li><li> [`new GUID()`](https://javadoc.io/static/com.github.f4b6a3/uuid-creator/5.3.7/com.github.f4b6a3.uuid/com/github/f4b6a3/uuid/alt/GUID.html#%3Cinit%3E(java.lang.String)). </li></ul> |

This project contains a [micro benchmark](https://github.com/f4b6a3/uuid-creator/tree/master/benchmark) and a good amount of [unit tests](https://github.com/f4b6a3/uuid-creator/tree/master/src/test/java/com/github/f4b6a3/uuid).

Read the [Wiki pages](https://github.com/f4b6a3/uuid-creator/wiki) and the [Javadocs](https://javadoc.io/doc/com.github.f4b6a3/uuid-creator).

> **HINT:**
> A UUID version is a [**UUID subtype**](https://www.rfc-editor.org/rfc/rfc9562#name-iana-uuid-subtype-registry-). The word "version" is not used in the sense that a higher version number makes the previous one obsolete. There are 8 subtypes of UUID and each of them is assigned a number; for example, a UUIDv7 is a UUID of subtype 7. Likewise, a UUID variant is a [**UUID type**](https://www.rfc-editor.org/rfc/rfc9562#section-4.1). There are 4 types of UUID: (1) the prehistoric one, (2) the one described in RFC 9562, (3) the one belonging to Microsoft and (4) the one reserved for the future. The RFC 9562 retain the terms "version" and "variant" for compatibility with previous specificantions and existing implementations.
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