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

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

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

    public class UID

extends Base
implements java.lang.Comparable, java.io.Serializable, PortableObject

A UID is a 128-bit identifier that is almost guaranteed to be unique.

Author:
  cp 2000.09.12

Constructor Summary
`UID()` Construct a UID (default constructor).
`UID(byte[] ab)` Construct a UID from a byte array.
`UID(java.io.DataInput stream)` Construct a UID from a stream.
`UID(int nAddr, long lDatetime, int nCount)` Construct a UID from its constituent members (advanced constructor).
`UID(java.lang.String s)` Construct a UID 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 UIDs are equal.
`int` | `getAddress()` Determine the internet address of the host that generated the UID instance (or a random number if no internet address was available)
`int` | `getCount()` Determine the "counter" portion of the UID that ensures that two UIDs generated at the same exact time by the same process are unique.
`long` | `getTimestamp()` Determine the date/time value that the UID instance was generated.
`int` | `hashCode()` Determine a hash code for the UID object.
`static void` | `main(java.lang.String[] asArgs)` Allow UID identifiers to be generated or parsed at the command line.
`void` | `readExternal(java.io.DataInput in)`
`void` | `readExternal(PofReader in)` Restore the contents of a user type instance by reading its state using the specified PofReader object.
`void` | `save(java.io.DataOutput stream)` Store this UID in a stream.
`byte[]` | `toByteArray()` Convert the UID to a byte array of 16 bytes.
`char[]` | `toCharArray()` Convert the UID to a character array of 32 hex digits.
`static long` | `toLong(java.net.InetAddress addr)` Converts and IP address to a long value.
`java.lang.String` | `toString()` Convert the UID to a printable String.
`static java.lang.String` | `toString(long l)` Converts a long value to an address string in the form returned by InetAddress#getHostAddress.
`void` | `writeExternal(java.io.DataOutput out)`
`void` | `writeExternal(PofWriter out)` Save the contents of a POF user type instance by writing its state using the specified PofWriter object.

Constructor Detail

### UID

    public UID()

  Construct a UID (default constructor).

### UID

    public UID(int nAddr,
               long lDatetime,
               int nCount)

  Construct a UID from its constituent members (advanced constructor).

  Parameters:
    `nAddr` - the InetAddress-related portion of the UID
    `lDatetime` - the creation date/time millis portion of the UID
    `nCount` - the counter portion of the UID

### UID

    public UID(byte[] ab)

  Construct a UID from a byte array.

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

### UID

    public UID(java.lang.String s)

  Construct a UID from a String.

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

### UID

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

  Construct a UID from a stream. This is a custom serialization implementation that is unrelated to the Serializable interface and the Java implementation of persistence.

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

### getAddress

    public int getAddress()

  Determine the internet address of the host that generated the UID instance (or a random number if no internet address was available)

  Returns:
    a 4-byte integer value holding an internet address in the byte order that is used by InetAddress and LicensedObject

### getTimestamp

    public long getTimestamp()

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

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

### getCount

    public int getCount()

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

  Returns:
    a number that helps to make the UID unique

### toString

    public java.lang.String toString()

  Convert the UID to a printable String.

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

### toByteArray

    public byte[] toByteArray()

  Convert the UID to a byte array of 16 bytes.

  Returns:
    the UID data as a byte array of 16 bytes

### toCharArray

    public char[] toCharArray()

  Convert the UID to a character array of 32 hex digits.

  Returns:
    the UID data as a character array of 32 hex digits

### equals

    public boolean equals(java.lang.Object o)

  Determine if two UIDs are equal.

  Parameters:
    `o` - the other UID
  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 UID object.

  Returns:
    a hash code reflecting the UID's data

### save

    public void save(java.io.DataOutput stream)
              throws java.io.IOException

  Store this UID in a stream. This is a custom serialization implementation that is unrelated to the Serializable interface and the Java implementation of persistence.

  Parameters:
    `stream` - an object implementing java.io.DataOutput that this UID should write its internal information to.
  Throws:
    `java.io.IOException` - if an error occurs writing to the stream

### readExternal

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

  Throws:
    `java.io.IOException`

### writeExternal

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

  Throws:
    `java.io.IOException`

### 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

### toLong

    public static long toLong(java.net.InetAddress addr)

  Converts and IP address to a long value.

  Parameters:
    `addr` - an instance of InetAddress to convert to a long
  Returns:
    a long value holding the IP address

### toString

    public static java.lang.String toString(long l)

  Converts a long value to an address string in the form returned by InetAddress#getHostAddress.

  Parameters:
    `l` - the long value holding the IP address
  Returns:
    the IP address string "%d.%d.%d.%d"

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Oracle® Coherence Java API Reference
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E15583-01
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