Constructor Summary

Method Summary

Constructor Details

• UUID

  public UUID(long mostSigBits, long leastSigBits)

  Constructs a newUUID using the specified data. mostSigBits is used for the most significant 64 bits of the UUID andleastSigBits becomes the least significant 64 bits of theUUID.

  Parameters:

  mostSigBits - The most significant bits of theUUID

  leastSigBits - The least significant bits of theUUID

Method Details

• randomUUID

  public static UUID randomUUID()

  Static factory to retrieve a type 4 (pseudo randomly generated) UUID. TheUUID is generated using a cryptographically strong pseudo random number generator.

  Returns:

  A randomly generatedUUID

• nameUUIDFromBytes

  public static UUID nameUUIDFromBytes(byte[] name)

  Static factory to retrieve a type 3 (name based)UUID based on the specified byte array.

  Parameters:

  name - A byte array to be used to construct aUUID

  Returns:

  AUUID generated from the specified array

• fromString

  public static UUID fromString(String name)

  Creates aUUID from the string standard representation as described in thetoString() method.

  Parameters:

  name - A string that specifies aUUID

  Returns:

  AUUID with the specified value

  Throws:

  IllegalArgumentException - If name does not conform to the string representation as described intoString()

• getLeastSignificantBits

  public long getLeastSignificantBits()

  Returns the least significant 64 bits of this UUID's 128 bit value.

  Returns:

  The least significant 64 bits of this UUID's 128 bit value

• getMostSignificantBits

  public long getMostSignificantBits()

  Returns the most significant 64 bits of this UUID's 128 bit value.

  Returns:

  The most significant 64 bits of this UUID's 128 bit value

• version

  public int version()

  The version number associated with thisUUID. The version number describes how thisUUID was generated. The version number has the following meaning:

  • 1 Time-based UUID
  • 2 DCE security UUID
  • 3 Name-based UUID
  • 4 Randomly generated UUID

  Returns:

  The version number of thisUUID

• variant

  public int variant()

  The variant number associated with thisUUID. The variant number describes the layout of theUUID. The variant number has the following meaning:

  • 0 Reserved for NCS backward compatibility
  • 2IETF RFC 4122 (Leach-Salz), used by this class
  • 6 Reserved, Microsoft Corporation backward compatibility
  • 7 Reserved for future definition

  Returns:

  The variant number of thisUUID

  External Specifications

  • RFC 4122: A Universally Unique IDentifier (UUID) URN Namespace

• timestamp

  public long timestamp()

  The timestamp value associated with this UUID.

  The 60 bit timestamp value is constructed from the time_low, time_mid, and time_hi fields of thisUUID. The resulting timestamp is measured in 100-nanosecond units since midnight, October 15, 1582 UTC.

  The timestamp value is only meaningful in a time-based UUID, which has version type 1. If thisUUID is not a time-based UUID then this method throws UnsupportedOperationException.

  Returns:

  The timestamp of thisUUID.

  Throws:

  UnsupportedOperationException - If this UUID is not a version 1 UUID

• clockSequence

  public int clockSequence()

  The clock sequence value associated with this UUID.

  The 14 bit clock sequence value is constructed from the clock sequence field of this UUID. The clock sequence field is used to guarantee temporal uniqueness in a time-based UUID.

  TheclockSequence value is only meaningful in a time-based UUID, which has version type 1. If this UUID is not a time-based UUID then this method throws UnsupportedOperationException.

  Returns:

  The clock sequence of thisUUID

  Throws:

  UnsupportedOperationException - If this UUID is not a version 1 UUID

• node

  public long node()

  The node value associated with this UUID.

  The 48 bit node value is constructed from the node field of this UUID. This field is intended to hold the IEEE 802 address of the machine that generated this UUID to guarantee spatial uniqueness.

  The node value is only meaningful in a time-based UUID, which has version type 1. If this UUID is not a time-based UUID then this method throws UnsupportedOperationException.

  Returns:

  The node value of thisUUID

  Throws:

  UnsupportedOperationException - If this UUID is not a version 1 UUID

• toString

  public String toString()

  Returns aString object representing thisUUID.

  The UUID string representation is as described by this BNF:

   UUID                   = <time_low> "-" <time_mid> "-"                          <time_high_and_version> "-"                          <variant_and_sequence> "-"                          <node> time_low               = 4*<hexOctet> time_mid               = 2*<hexOctet> time_high_and_version  = 2*<hexOctet> variant_and_sequence   = 2*<hexOctet> node                   = 6*<hexOctet> 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"

  Overrides:

  toString in class Object

  Returns:

  A string representation of thisUUID

• hashCode

  public int hashCode()

  Returns a hash code for thisUUID.

  Overrides:

  hashCode in class Object

  Returns:

  A hash code value for thisUUID

  See Also:

  • Object.equals(java.lang.Object)
  • System.identityHashCode(java.lang.Object)

• equals

  public boolean equals(Object obj)

  Compares this object to the specified object. The result is true if and only if the argument is notnull, is aUUID object, has the same variant, and contains the same value, bit for bit, as thisUUID.

  Overrides:

  equals in class Object

  Parameters:

  obj - The object to be compared

  Returns:

  true if the objects are the same;false otherwise

  See Also:

  • Object.hashCode()
  • HashMap

• compareTo

  public int compareTo(UUID val)

  Compares this UUID with the specified UUID.

  The first of two UUIDs is greater than the second if the most significant field in which the UUIDs differ is greater for the first UUID.

  Specified by:

  compareTo in interface Comparable<UUID>

  Parameters:

  val -UUID to which thisUUID is to be compared

  Returns:

  -1, 0 or 1 as thisUUID is less than, equal to, or greater thanval