UUID (Java Platform SE 8 )

java.lang.Object
- java.util.UUID

All Implemented Interfaces:

Serializable, Comparable<UUID>
```
public final class UUID
extends Object
implements Serializable, Comparable<UUID>
```
A class that represents an immutable universally unique identifier (UUID). A UUID represents a 128-bit value.
There exist different variants of these global identifiers. The methods of this class are for manipulating the Leach-Salz variant, although the constructors allow the creation of any variant of UUID (described below).
The layout of a variant 2 (Leach-Salz) UUID is as follows: The most significant long consists of the following unsigned fields:
```
 0xFFFFFFFF00000000 time_low
 0x00000000FFFF0000 time_mid
 0x000000000000F000 version
 0x0000000000000FFF time_hi
 
```
The least significant long consists of the following unsigned fields:
```
 0xC000000000000000 variant
 0x3FFF000000000000 clock_seq
 0x0000FFFFFFFFFFFF node
 
```
The variant field contains a value which identifies the layout of the UUID. The bit layout described above is valid only for a UUID with a variant value of 2, which indicates the Leach-Salz variant.
The version field holds a value that describes the type of this UUID. There are four different basic types of UUIDs: time-based, DCE security, name-based, and randomly generated UUIDs. These types have a version value of 1, 2, 3 and 4, respectively.
For more information including algorithms used to create UUIDs, see RFC 4122: A Universally Unique IDentifier (UUID) URN Namespace, section 4.2 "Algorithms for Creating a Time-Based UUID".
Since:

1.5

See Also:

Serialized Form

Class UUID