The specific use of the Java UUID

Reference JDK




UUIDextends objectimplements Serializable, comparable<uuid>

A class that represents a universally unique identifier (UUID). The UUID represents a 128-bit value.

These generic identifiers have different variants. This class of methods is used to manipulate the Leach-salz variant, although the construction method allows any UUID variants to be created (described below).

The layout of the Variant 2 (Leach-salz) UUID is as follows: The most significant bit of the long data consists of the following unsigned fields:

The least significant bit of long data consists of the following unsigned fields:

The Variant field contains a value that represents the layout of the UUID . The bit layout described above only works when the variant value of the UUID is 2 (representing the Leach-salz variant).

The version field holds a value that describes this UUID type. There are 4 different basic UUID types: A time-based UUID, a DCE security uuid, a name-based UUID, and a randomly generated UUID. The version values for these types are 1, 2, 3, and 4, respectively.

For more information about the algorithm used to create the UUID , see RFC 4122: Universal Unique identifier (universally unique Identifier) (UUID) URN Namespace, section 4.2 "; Create a time-based UUID" algorithm.

Start from the following versions:

1.5

See also:

Serialization Table

Construction Method Summary
UUID(long mostSigBits, long leastSigBits) Constructs a new UUIDusing the specified data.

Method Summary
int	clockSequence() The value of the clock sequence associated with this UUID.
int	compareTo(UUID val) Compares this UUID to a specified UUID.
boolean	equals(Object obj) Compares this object to a specified object.
static UUID	fromString(String name) toString()creates a UUIDbased on the string standard representation described in the method.
long	getLeastSignificantBits() Returns the lowest valid 64 bits in the 128-bit value of this UUID.
long	getMostSignificantBits() Returns the most significant 64 bits in the 128-bit value of this UUID.
int	hashCode() Returns the UUID hash code for this.
static UUID	nameUUIDFromBytes(byte[] name) Gets a static factory of type 3 (name-based)UUID , based on the specified byte array.
long	node() The node value associated with this UUID.
static UUID	randomUUID() Gets the static factory of type 4 (pseudo-randomly generated) UUID.
long	timestamp() The timestamp value associated with this UUID.
String	toString() Returns the object that represents this UUID String .
int	variant() The variant number associated with this UUID .
int	version() The version number associated with this UUID .

Methods of inheriting from class Java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

The specific use of the Java UUID