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Summary: Ctors | Methods | Inherited Methods | [Expand All]

Added in API level 1

public final class

UUID

extends Object
implements Serializable Comparable <T>

java.lang.Object
↳	java.util.UUID

Class Overview

UUID is an immutable representation of a 128-bit universally unique identifier (UUID).

There are multiple, variant layouts of UUIDs, but this class is based upon variant 2 of RFC 4122 , the Leach-Salz variant. This class can be used to model alternate variants, but most of the methods will be unsupported in those cases; see each method for details.

Summary

Public Constructors
	UUID (long mostSigBits, long leastSigBits) Constructs an instance with the specified bits.

Public Methods
int	clockSequence () The clock sequence value of the version 1, variant 2 UUID as per RFC 4122 .
int	compareTo ( UUID uuid) Compares this UUID to the specified UUID.
boolean	equals ( Object object) Compares this UUID to another object for equality.
static UUID	fromString ( String uuid) Parses a UUID string with the format defined by `toString()` .
long	getLeastSignificantBits () The 64 least significant bits of the UUID.
long	getMostSignificantBits () The 64 most significant bits of the UUID.
int	hashCode () Returns a hash value for this UUID that is consistent with the `equals(Object)` method.
static UUID	nameUUIDFromBytes (byte[] name) Generates a variant 2, version 3 (name-based, MD5-hashed) UUID as per RFC 4122 .
long	node () The node value of the version 1, variant 2 UUID as per RFC 4122 .
static UUID	randomUUID () Generates a variant 2, version 4 (randomly generated number) UUID as per RFC 4122 .
long	timestamp () The timestamp value of the version 1, variant 2 UUID as per RFC 4122 .
String	toString () Returns a string representation of this UUID in the following format, as per RFC 4122 .
int	variant () The variant of the UUID as per RFC 4122 .
int	version () The version of the variant 2 UUID as per RFC 4122 .

[Expand]

Inherited Methods

From class java.lang.Object

Object	clone () Creates and returns a copy of this `Object` .
boolean	equals ( Object o) Compares this instance with the specified object and indicates if they are equal.
void	finalize () Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class <?>	getClass () Returns the unique instance of `Class` that represents this object's class.
int	hashCode () Returns an integer hash code for this object.
final void	notify () Causes a thread which is waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
final void	notifyAll () Causes all threads which are waiting on this object's monitor (by means of calling one of the `wait()` methods) to be woken up.
String	toString () Returns a string containing a concise, human-readable description of this object.
final void	wait () Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object.
final void	wait (long millis, int nanos) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.
final void	wait (long millis) Causes the calling thread to wait until another thread calls the `notify()` or `notifyAll()` method of this object or until the specified timeout expires.

From interface java.lang.Comparable

Public Constructors

public UUID (long mostSigBits, long leastSigBits)

Added in API level 1

Constructs an instance with the specified bits.

Parameters

mostSigBits	The 64 most significant bits of the UUID.
leastSigBits	The 64 least significant bits of the UUID.

Public Methods

public int clockSequence ()

Added in API level 1

The clock sequence value of the version 1, variant 2 UUID as per RFC 4122 .

Returns

a long value.

Throws

UnsupportedOperationException	if `version()` is not 1.

public int compareTo ( UUID uuid)

Added in API level 1

Compares this UUID to the specified UUID. The natural ordering of UUIDs is based upon the value of the bits from most significant to least significant.

Parameters

uuid	the UUID to compare to.

Returns

a value of -1, 0 or 1 if this UUID is less than, equal to or greater than uuid .

public boolean equals ( Object object)

Added in API level 1

Compares this UUID to another object for equality. If object is not null , is a UUID instance, and all bits are equal, then true is returned.

Parameters

object	the `Object` to compare to.

Returns

true if this UUID is equal to object or false if not.

public static UUID fromString ( String uuid)

Added in API level 1

Parses a UUID string with the format defined by toString() .

Parameters

uuid	the UUID string to parse.

Returns

an UUID instance.

Throws

NullPointerException	if `uuid` is `null` .
IllegalArgumentException	if `uuid` is not formatted correctly.

public long getLeastSignificantBits ()

Added in API level 1

The 64 least significant bits of the UUID.

Returns

the 64 least significant bits.

public long getMostSignificantBits ()

Added in API level 1

The 64 most significant bits of the UUID.

Returns

the 64 most significant bits.

public int hashCode ()

Added in API level 1

Returns a hash value for this UUID that is consistent with the equals(Object) method.

Returns

an int value.

public static UUID nameUUIDFromBytes (byte[] name)

Added in API level 1

Generates a variant 2, version 3 (name-based, MD5-hashed) UUID as per RFC 4122 .

Parameters

name	the name used as byte array to create an UUID.

Returns

an UUID instance.

public long node ()

Added in API level 1

The node value of the version 1, variant 2 UUID as per RFC 4122 .

Returns

a long value.

Throws

UnsupportedOperationException	if `version()` is not 1.

public static UUID randomUUID ()

Added in API level 1

Generates a variant 2, version 4 (randomly generated number) UUID as per RFC 4122 .

Returns

an UUID instance.

public long timestamp ()

Added in API level 1

The timestamp value of the version 1, variant 2 UUID as per RFC 4122 .

Returns

a long value.

Throws

UnsupportedOperationException	if `version()` is not 1.

public String toString ()

Added in API level 1

Returns a string representation of this UUID in the following format, as per RFC 4122 .

          UUID                   = time-low "-" time-mid "-"
                                     time-high-and-version "-"
                                     clock-seq-and-reserved
                                     clock-seq-low "-" node
            time-low               = 4hexOctet
            time-mid               = 2hexOctet
            time-high-and-version  = 2hexOctet
            clock-seq-and-reserved = hexOctet
            clock-seq-low          = hexOctet
            node                   = 6hexOctet
            hexOctet               = hexDigit hexDigit
            hexDigit =
                "0" / "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" / "9" /
                "a" / "b" / "c" / "d" / "e" / "f" /
                "A" / "B" / "C" / "D" / "E" / "F"

Returns

a String instance.

public int variant ()

Added in API level 1

The variant of the UUID as per RFC 4122 .

0 - Reserved for NCS compatibility
2 - RFC 4122/Leach-Salz
6 - Reserved for Microsoft Corporation compatibility
7 - Reserved for future use

Returns

an int value.

public int version ()

Added in API level 1

The version of the variant 2 UUID as per RFC 4122 . If the variant is not 2, then the version will be 0.

1 - Time-based UUID
2 - DCE Security UUID
3 - Name-based with MD5 hashing UUID ( nameUUIDFromBytes(byte[]) )
4 - Randomly generated UUID ( randomUUID() )
5 - Name-based with SHA-1 hashing UUID

Returns

an int value.

Results

Interfaces

Classes

Enums

Exceptions

Errors

UUID

Class Overview

Summary

Public Constructors

public UUID (long mostSigBits, long leastSigBits)

Parameters

Public Methods

public int clockSequence ()

Returns

Throws

public int compareTo ( UUID uuid)

Parameters

Returns

public boolean equals ( Object object)

Parameters

Returns

public static UUID fromString ( String uuid)

Parameters

Returns

Throws

public long getLeastSignificantBits ()

Returns

public long getMostSignificantBits ()

Returns

public int hashCode ()

Returns

public static UUID nameUUIDFromBytes (byte[] name)

Parameters

Returns

public long node ()

Returns

Throws

public static UUID randomUUID ()

Returns

public long timestamp ()

Returns

Throws

public String toString ()

Returns

public int variant ()

Returns

public int version ()

Returns