UUID (RVPF-Core API Documentation)

Object
- UUID

All Implemented Interfaces:

Serializable, Comparable<UUID>
```
@Immutable
public final class UUID
extends Object
implements Serializable, Comparable<UUID>
```
Universally Unique IDentifier.
This class implements version 4 (pseudo-randomly generated) of the RFC 4122 variant of the UUID namespace.

Some debugging use cases benefit from being able to identify the machine from which a UUID has been generated. To allow for this, a system property ("rvpf.uuid.mac") allows the use of the MAC address of a specified or default interface to be used as the node value in each generated UUID, like it would be for a version 1 (time-based) UUID.

UUID values are frequently used as primary keys in databases. A special bit manipulation allows the key value to be identified as deleted: the variant field is modified to make the UUID use the NCS compatibility value which is not accepted as valid for original keys where deleted entries may be present.

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`BYTES_LENGTH` Length of a byte array containing a UUID.
`static String`	`MAC_ADDRESS_PROPERTY` Include MAC address property (may specify interface).
`static int`	`NAME_LENGTH` Name length.
`static UUID`	`NULL` Null UUID.
`static int`	`RAW_STRING_LENGTH` Length of a String containing a raw UUID.
`static int`	`STRING_LENGTH` Length of a String containing a decorated UUID.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`int`	`compareTo(UUID other)` Implements Comparable.
`UUID`	`deleted()` Returns this or a clone of this with the 'deleted' indicator set.
`boolean`	`equals(Object other)`
`static UUID`	`fromBytes(byte[] bytes)` Returns a new UUID from a byte array.
`static Optional<UUID>`	`fromDataInput(DataInput source)` Reads in an external representation of a UUID.
`static UUID`	`fromLongs(long high, long low)` Returns a new UUID from two longs.
`static UUID`	`fromName(String name)` Returns a new UUID from a name generated by `toName()`.
`static Optional<UUID>`	`fromString(String string)` Returns a new UUID from a string.
`static UUID`	`generate()` Generates a UUID.
`static UUID`	`generate(Optional<byte[]> seed)` Generates a version 4 UUID (IETF RFC 4122).
`static UUID`	`generate(String seed)` Generates a UUID.
`long`	`getHigh()` Gets back the high value from a synthesized UUID.
`long`	`getLeastSignificantBits()` Gets the least significant bits.
`long`	`getLow()` Gets back the low value from a synthesized UUID.
`int`	`getMidHigh()` Gets back the mid high value from a synthesized UUID.
`int`	`getMidLow()` Gets back the mid low value from a synthesized UUID.
`long`	`getMostSignificantBits()` Gets the most significant bits.
`static Optional<byte[]>`	`getNode()` Gets the node part.
`int`	`hashCode()`
`boolean`	`isDeleted()` Asks if this represents a deleted entry.
`boolean`	`isRandomNode()` Asks if this contains a random node.
`static boolean`	`isUUID(String key)` Asks if a key string can represent a UUID.
`static Optional<UUID>`	`readExternal(ObjectInput source)` Reads in an external representation of a UUID.
`static UUID`	`synthesize(long high, int midHigh, int midLow, long low)` Synthesizes a UUID from four numbers.
`byte[]`	`toBytes()` Returns a binary representation of itself.
`void`	`toDataOutput(DataOutput destination)` Sends to a data output.
`String`	`toName()` Returns a name representation of itself.
`String`	`toRawString()` Returns an undecorated string representation of itself.
`String`	`toString()` Returns a decorated string representation of itself.
`String`	`toURN()` Returns a URN reference to this.
`UUID`	`undeleted()` Returns this or a clone of this with the 'deleted' indicator cleared.
`static void`	`writeExternal(Optional<UUID> uuid, ObjectOutput destination)` Writes out an external representation of a UUID.

Methods inherited from class Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - BYTES_LENGTH
```
public static final int BYTES_LENGTH
```
    Length of a byte array containing a UUID.
    
    See Also:
    
    Constant Field Values
  - MAC_ADDRESS_PROPERTY
```
public static final String MAC_ADDRESS_PROPERTY
```
    Include MAC address property (may specify interface).
    
    See Also:
    
    Constant Field Values
  - NAME_LENGTH
```
public static final int NAME_LENGTH
```
    Name length.
    
    See Also:
    
    Constant Field Values
  - NULL
```
public static final UUID NULL
```
    Null UUID.
  - RAW_STRING_LENGTH
```
public static final int RAW_STRING_LENGTH
```
    Length of a String containing a raw UUID.
  - STRING_LENGTH
```
public static final int STRING_LENGTH
```
    Length of a String containing a decorated UUID.
- Method Detail
  - fromBytes
```
@Nonnull
 @CheckReturnValue
public static UUID fromBytes(@Nonnull
                                                           byte[] bytes)
```
    Returns a new UUID from a byte array.
    
    Parameters:
    
    bytes - Binary value for the UUID in 16 bytes.
    
    Returns:
    
    The new UUID.
  - fromDataInput
```
@Nonnull
 @CheckReturnValue
public static Optional<UUID> fromDataInput(@Nonnull
                                                                         DataInput source)
                                                                  throws IOException
```
    Reads in an external representation of a UUID.
    
    Parameters:
    
    source - The source.
    
    Returns:
    
    The UUID (may be empty).
    
    Throws:
    
    IOException - When an I/O error occurs.
  - fromLongs
```
@Nonnull
 @CheckReturnValue
public static UUID fromLongs(long high,
                                                           long low)
```
    Returns a new UUID from two longs.
    This convenience method is used to convert from a UUID.
    
    Parameters:
    
    high - The most significant bits.
    
    low - The least significant bits.
    
    Returns:
    
    The new UUID.
  - fromName
```
@Nonnull
 @CheckReturnValue
public static UUID fromName(@Nonnull
                                                          String name)
```
    Returns a new UUID from a name generated by toName().
    
    Parameters:
    
    name - The previously generated name.
    
    Returns:
    
    The new UUID.
  - fromString
```
@Nonnull
 @CheckReturnValue
public static Optional<UUID> fromString(@Nonnull
                                                                      String string)
```
    Returns a new UUID from a string.
    
    Parameters:
    
    string - A string of 32 hexadecimal digits for the UUID. It may include '-' decorators. When empty, an empty value is returned.
    
    Returns:
    
    The new UUID or empty.
  - generate
```
@Nonnull
 @CheckReturnValue
public static UUID generate()
```
    Generates a UUID.
    
    Returns:
    
    The new UUID.
  - generate
```
@Nonnull
 @CheckReturnValue
public static UUID generate(@Nonnull
                                                          Optional<byte[]> seed)
```
    Generates a version 4 UUID (IETF RFC 4122).
    
    Parameters:
    
    seed - A value prefix (may be null).
    
    Returns:
    
    The new UUID.
  - generate
```
@Nonnull
 @CheckReturnValue
public static UUID generate(@Nonnull
                                                          String seed)
```
    Generates a UUID.
    
    Parameters:
    
    seed - A value prefix (may be empty).
    
    Returns:
    
    The new UUID.
  - getNode
```
@Nonnull
 @CheckReturnValue
public static Optional<byte[]> getNode()
```
    Gets the node part.
    
    Returns:
    
    The node part (empty if not a MAC address).
  - isUUID
```
@CheckReturnValue
public static boolean isUUID(@Nonnull
                                                String key)
```
    Asks if a key string can represent a UUID.
    
    Parameters:
    
    key - The candidate key string.
    
    Returns:
    
    A true value if it would be accepted.
  - readExternal
```
@Nonnull
 @CheckReturnValue
public static Optional<UUID> readExternal(@Nonnull
                                                                        ObjectInput source)
                                                                 throws IOException
```
    Reads in an external representation of a UUID.
    This is a helper method for Externalizable objects containing a UUID.
    
    Parameters:
    
    source - The source.
    
    Returns:
    
    The optional UUID.
    
    Throws:
    
    IOException - When an I/O error occurs.
  - synthesize
```
@Nonnull
 @CheckReturnValue
public static UUID synthesize(long high,
                                                            int midHigh,
                                                            int midLow,
                                                            long low)
```
    Synthesizes a UUID from four numbers.
    
    Parameters:
    
    high - A 48 bits number.
    
    midHigh - A 8 bits number.
    
    midLow - A 8 bits number.
    
    low - A 40 bits number.
    
    Returns:
    
    The UUID.
  - writeExternal
```
public static void writeExternal(@Nonnull
                                 Optional<UUID> uuid,
                                 @Nonnull
                                 ObjectOutput destination)
                          throws IOException
```
    Writes out an external representation of a UUID.
    This is a helper method for Externalizable objects containing a UUID.
    
    Parameters:
    
    uuid - The UUID (may be empty).
    
    destination - The destination.
    
    Throws:
    
    IOException - When an I/O error occurs.
  - compareTo
```
public int compareTo(UUID other)
```
    Implements Comparable.
    
    Specified by:
    
    compareTo in interface Comparable<UUID>
    
    Parameters:
    
    other - An other PointEntity.
    
    Returns:
    
    A negative integer, zero, or a positive integer.
  - deleted
```
@Nonnull
 @CheckReturnValue
public UUID deleted()
```
    Returns this or a clone of this with the 'deleted' indicator set.
    If the 'deleted' indicator is already set, returns this.
    
    Returns:
    
    A 'deleted' UUID.
  - equals
```
public boolean equals(Object other)
```
    Overrides:
    
    equals in class Object
  - getHigh
```
@CheckReturnValue
public long getHigh()
```
    Gets back the high value from a synthesized UUID.
    
    Returns:
    
    The high value (48 bits).
  - getLeastSignificantBits
```
@CheckReturnValue
public long getLeastSignificantBits()
```
    Gets the least significant bits.
    This convenience method is used to help convert to UUID.
    
    Returns:
    
    The least significant bits.
  - getLow
```
@CheckReturnValue
public long getLow()
```
    Gets back the low value from a synthesized UUID.
    
    Returns:
    
    The low value (40 bits).
  - getMidHigh
```
@CheckReturnValue
public int getMidHigh()
```
    Gets back the mid high value from a synthesized UUID.
    
    Returns:
    
    The mid high value (8 bits).
  - getMidLow
```
@CheckReturnValue
public int getMidLow()
```
    Gets back the mid low value from a synthesized UUID.
    
    Returns:
    
    The mid low value (8 bits).
  - getMostSignificantBits
```
@CheckReturnValue
public long getMostSignificantBits()
```
    Gets the most significant bits.
    This convenience method is used to help convert to UUID.
    
    Returns:
    
    The most significant bits.
  - hashCode
```
public int hashCode()
```
    Overrides:
    
    hashCode in class Object
  - isDeleted
```
@CheckReturnValue
public boolean isDeleted()
```
    Asks if this represents a deleted entry.
    
    Returns:
    
    A true value if deleted.
  - isRandomNode
```
@CheckReturnValue
public boolean isRandomNode()
```
    Asks if this contains a random node.
    Note: some UUID generators do not interpret correctly the position of the multicast bit in RFC 4122.
    
    Returns:
    
    A true if this contains a random node.
  - toBytes
```
@Nonnull
 @CheckReturnValue
public byte[] toBytes()
```
    Returns a binary representation of itself.
    
    Returns:
    
    A clone of its bytes.
  - toDataOutput
```
public void toDataOutput(@Nonnull
                         DataOutput destination)
                  throws IOException
```
    Sends to a data output.
    
    Parameters:
    
    destination - The destination.
    
    Throws:
    
    IOException - On I/O exception.
  - toName
```
@Nonnull
 @CheckReturnValue
public String toName()
```
    Returns a name representation of itself.
    
    Returns:
    
    An undecorated string of 25 base 36 digits.
  - toRawString
```
@Nonnull
 @CheckReturnValue
public String toRawString()
```
    Returns an undecorated string representation of itself.
    
    Returns:
    
    An undecorated string of hexadecimal digits.
  - toString
```
public String toString()
```
    Returns a decorated string representation of itself.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    An decorated string of hexadecimal digits.
  - toURN
```
@Nonnull
 @CheckReturnValue
public String toURN()
```
    Returns a URN reference to this.
    
    Returns:
    
    The URN reference to this.
  - undeleted
```
@Nonnull
 @CheckReturnValue
public UUID undeleted()
```
    Returns this or a clone of this with the 'deleted' indicator cleared.
    If the 'deleted' indicator is already clear, returns this.
    
    Returns:
    
    An 'undeleted' UUID.

Class UUID

Field Summary

Method Summary

Methods inherited from class Object

Field Detail

BYTES_LENGTH

MAC_ADDRESS_PROPERTY

NAME_LENGTH

NULL

RAW_STRING_LENGTH

STRING_LENGTH

Method Detail

fromBytes

fromDataInput

fromLongs

fromName

fromString

generate

generate

generate

getNode

isUUID

readExternal

synthesize

writeExternal

compareTo

deleted

equals

getHigh

getLeastSignificantBits

getLow

getMidHigh

getMidLow

getMostSignificantBits

hashCode

isDeleted

isRandomNode

toBytes

toDataOutput

toName

toRawString

toString

toURN

undeleted