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Oracle® Coherence Java API Reference
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## com.tangosol.util
Class UUID

    java.lang.Object
      com.tangosol.util.Base
          com.tangosol.util.UUID

All Implemented Interfaces:
  ExternalizableLite, PortableObject, java.io.Externalizable, java.io.Serializable, java.lang.Comparable

    public final class UUID

extends Base
implements java.lang.Comparable, java.io.Externalizable, ExternalizableLite, PortableObject

A UUID is a 256-bit identifier that, if it is generated, is statistically guaranteed to be unique.

Author:
  cp 2004.06.24

Constructor Summary
`UUID()` Generate a UUID.
`UUID(byte[] ab)` Construct a UUID from a byte array.
`UUID(java.io.DataInput stream)` Construct a UUID from a stream.
`UUID(long lDatetime, byte[] abIP, int nPort, int nCount)` Build a UUID from its constituent members (advanced constructor).
`UUID(long lDatetime, java.net.InetAddress addr, int nPort, int nCount)` Build a UUID from its constituent members (advanced constructor).
`UUID(java.lang.String s)` Construct a UUID from a String.

Method Summary
`int` | `compareTo(java.lang.Object o)` Compares this object with the specified object for order.
`boolean` | `equals(java.lang.Object o)` Determine if two UUIDs are equal.
`byte[]` | `getAddress()` Determine the internet address of the host that generated the UUID instance.
`int` | `getCount()` Determine the "counter" portion of the UUID that ensures that two UUIDs generated at the same exact time by the same process are unique.
`int` | `getPort()` Determine the port portion of the UUID.
`long` | `getTimestamp()` Determine the date/time value that the UUID instance was generated.
`int` | `hashCode()` Determine a hash code for the UUID object.
`boolean` | `isAddressIncluded()` This is true if the IP address is a real IP address.
`boolean` | `isGenerated()` This is true if the UUID was generated, and false if it was built.
`static void` | `main(java.lang.String[] asArgs)` Allow UUID identifiers to be generated or parsed at the command line.
`void` | `readExternal(java.io.DataInput in)` Restore the contents of this object by loading the object's state from the passed DataInput object.
`void` | `readExternal(java.io.ObjectInput in)` Read this object from an ObjectInputStream.
`void` | `readExternal(PofReader in)` Restore the contents of a user type instance by reading its state using the specified PofReader object.
`byte[]` | `toByteArray()` Convert the UUID to a byte array of 32 bytes.
`java.lang.String` | `toString()` Convert the UUID to a printable String.
`void` | `writeExternal(java.io.DataOutput out)` Save the contents of this object by storing the object's state into the passed DataOutput object.
`void` | `writeExternal(java.io.ObjectOutput out)` Write this object to an ObjectOutputStream.
`void` | `writeExternal(PofWriter out)` Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Constructor Detail

### UUID

    public UUID()

  Generate a UUID.

### UUID

    public UUID(long lDatetime,
                java.net.InetAddress addr,
                int nPort,
                int nCount)

  Build a UUID from its constituent members (advanced constructor).

  It is guaranteed that a generated UUID will never equal a built UUID.

  Parameters:
    `lDatetime` - the creation date/time millis portion of the UUID
    `addr` - the InetAddress portion of the UUID
    `nPort` - the port number portion of the UUID; a port number is 16 bits, but up to 28 bits of data from this value will be maintained by the UUID
    `nCount` - the counter portion of the UUID

### UUID

    public UUID(long lDatetime,
                byte[] abIP,
                int nPort,
                int nCount)

  Build a UUID from its constituent members (advanced constructor).

  It is guaranteed that a generated UUID will never equal a built UUID.

  Parameters:
    `lDatetime` - the creation date/time millis portion of the UUID
    `abIP` - the InetAddress portion of the UUID
    `nPort` - the port number portion of the UUID; a port number is 16 bits, but up to 28 bits of data from this value will be maintained by the UUID
    `nCount` - the counter portion of the UUID

### UUID

    public UUID(java.lang.String s)

  Construct a UUID from a String.

  Parameters:
    `s` - a String as would be returned from UUID.toString()

### UUID

    public UUID(byte[] ab)

  Construct a UUID from a byte array.

  Parameters:
    `ab` - a byte array as would be returned from UUID.toByteArray()

### UUID

    public UUID(java.io.DataInput stream)
         throws java.io.IOException

  Construct a UUID from a stream.

  This is a helper constructor that is just a shorthand for a sequence:

         UUID uid = new UUID();
         uid.readExternal(stream);

  Parameters:
    `stream` - an object implementing java.io.DataInput that contains the internal information that a previous UID wrote
  Throws:
    `java.io.IOException` - if an error occurs reading from the stream

Method Detail

### main

    public static void main(java.lang.String[] asArgs)

  Allow UUID identifiers to be generated or parsed at the command line. For example, to generate 10 identifiers: java com.tangosol.util.UUID 10

### isGenerated

    public boolean isGenerated()

  This is true if the UUID was generated, and false if it was built. A generated UUID is universally unique. Note that the port number is random if the UUID is generated.

  Returns:
    true if the UUID was generated

### getTimestamp

    public long getTimestamp()

  Determine the date/time value that the UUID instance was generated.

  Returns:
    date/time value in millis that the UUID instance was generated

### isAddressIncluded

    public boolean isAddressIncluded()

  This is true if the IP address is a real IP address. This is only false if two conditions are met: The UUID is generated, and it could not get an IP address (or one that is not a loopback/localhost address) from the VM.

  Returns:
    true if the UUID has IP address information

### getAddress

    public byte[] getAddress()

  Determine the internet address of the host that generated the UUID instance.

  Returns:
    an array of bytes containing the IP address information; the array can be zero bytes (no address,) four bytes (IPv4) or 16 bytes (IPv6)

### getPort

    public int getPort()

  Determine the port portion of the UUID. Note that the port is a 28-bit value; the first nibble is always 0x0.

  Returns:
    the port portion of the UID

### getCount

    public int getCount()

  Determine the "counter" portion of the UUID that ensures that two UUIDs generated at the same exact time by the same process are unique.

  Returns:
    a number that helps to make the UUID unique

### toByteArray

    public byte[] toByteArray()

  Convert the UUID to a byte array of 32 bytes.

  Returns:
    the UUID data as a byte array of 32 bytes

### toString

    public java.lang.String toString()

  Convert the UUID to a printable String.

  Returns:
    the UUID data as a 0x-prefixed hex string.

### equals

    public boolean equals(java.lang.Object o)

  Determine if two UUIDs are equal.

  Parameters:
    `o` - the other UUID
  Returns:
    true if the passed object is equal to this

### compareTo

    public int compareTo(java.lang.Object o)

  Compares this object with the specified object for order. Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.

  Specified by:
    `compareTo` in interface `java.lang.Comparable`
  Parameters:
    `o` - the Object to be compared.
  Returns:
    a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object
  Throws:
    `java.lang.ClassCastException` - if the specified object's type prevents it from being compared to this Object

### hashCode

    public int hashCode()

  Determine a hash code for the UUID object.

  Returns:
    a hash code reflecting the UUID's data

### readExternal

    public void readExternal(java.io.ObjectInput in)
                      throws java.io.IOException

  Read this object from an ObjectInputStream.

  Specified by:
    `readExternal` in interface `java.io.Externalizable`
  Parameters:
    `in` - the ObjectInputStream to read this object from
  Throws:
    `java.io.IOException` - if an exception occurs reading this object

### writeExternal

    public void writeExternal(java.io.ObjectOutput out)
                       throws java.io.IOException

  Write this object to an ObjectOutputStream.

  Specified by:
    `writeExternal` in interface `java.io.Externalizable`
  Parameters:
    `out` - the ObjectOutputStream to write this object to
  Throws:
    `java.io.IOException` - thrown if an exception occurs writing this object

### readExternal

    public void readExternal(java.io.DataInput in)
                      throws java.io.IOException

  Restore the contents of this object by loading the object's state from the passed DataInput object.

  Specified by:
    `readExternal` in interface `ExternalizableLite`
  Parameters:
    `in` - the DataInput stream to read data from in order to restore the state of this object
  Throws:
    `java.io.IOException` - if an I/O exception occurs
    `java.io.NotActiveException` - if the object is not in its initial state, and therefore cannot be deserialized into

### writeExternal

    public void writeExternal(java.io.DataOutput out)
                       throws java.io.IOException

  Save the contents of this object by storing the object's state into the passed DataOutput object.

  Specified by:
    `writeExternal` in interface `ExternalizableLite`
  Parameters:
    `out` - the DataOutput stream to write the state of this object to
  Throws:
    `java.io.IOException` - if an I/O exception occurs

### readExternal

    public void readExternal(PofReader in)
                      throws java.io.IOException

  Restore the contents of a user type instance by reading its state using the specified PofReader object.

  Specified by:
    `readExternal` in interface `PortableObject`
  Parameters:
    `in` - the PofReader from which to read the object's state
  Throws:
    `java.io.IOException` - if an I/O error occurs

### writeExternal

    public void writeExternal(PofWriter out)
                       throws java.io.IOException

  Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

  Specified by:
    `writeExternal` in interface `PortableObject`
  Parameters:
    `out` - the PofWriter to which to write the object's state
  Throws:
    `java.io.IOException` - if an I/O error occurs

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Oracle® Coherence Java API Reference
v3.5.3
E15583-01
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