co.codewizards.cloudstore.core

Class Uid

java.lang.Object

co.codewizards.cloudstore.core.Uid

All Implemented Interfaces:

Serializable, Comparable<Uid>

public class Uid
extends Object
implements Comparable<Uid>, Serializable

Universal identifier similar to a UUID.

The main difference is the encoding which is optimized for brevity. In contrast to the hex-encoding used by UUID, the toString() method uses standard base64url (RFC 4648). The difference to normal base64 is that base64url replaces '+' by '-' and '/' by '_' in order to make the encoded string usable in URLs without any escaping.

Important: The string-representation is case-sensitive!

Examples showing the difference of UUID vs. Uid:

 WQL8yMHUQ4FhZrB0cLux5g
 WCRAGMeiz-2PPaKdmn-iww
 Jd6_KRqpMivfuxXO4JmwtQ
 284tn0-92bIMRNV_4M53Tg
 8b726260-f9f3-439b-bf21-615bb4b6731d
 34fadc2b-5a58-4de8-b04c-6f315a6598cd
 15c3f6cb-6275-4557-b24c-2cd57cd07a6d
 11934d8c-d201-4a95-a714-e03ff48f5053
 46875d87-01ef-4ece-98cf-5a96a5946ef7

A string-encoded UUID always has a length 36 characters, while a Uid always has a length of 22 characters. In other words, the strings are 38.89% shorter.

Instances of this class are immutable.

Author:

Marco หงุ่ยตระกูล-Schulze - marco at codewizards dot co

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
static int	LENGTH_BYTES Gets the length of an Uid in bytes.
static int	LENGTH_STRING Gets the length of an Uid in its String representation.

Constructor Summary

Constructors

Constructor and Description
Uid() Creates a new random Uid.
Uid(byte[] bytes)
Uid(long hi, long lo) Creates a new Uid with the given value.
Uid(String uidString) Creates a new Uid instance from the encoded value in uidString.

Method Summary

Modifier and Type	Method and Description
int	compareTo(Uid other)
boolean	equals(Object obj)
int	hashCode()
byte[]	toBytes()
String	toString() Gets a base64url-encoded string-representation of this Uid.
static Uid	valueOf(byte[] bytes) Creates a new Uid instance from the binary data in bytes.
static Uid	valueOf(String uidString) Creates a new Uid instance from the encoded value in uidString.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

LENGTH_BYTES

public static final int LENGTH_BYTES

Gets the length of an Uid in bytes.

See Also:

Constant Field Values

LENGTH_STRING

public static final int LENGTH_STRING

Gets the length of an Uid in its String representation.

See Also:

Constant Field Values

Constructor Detail

Uid

public Uid()

Creates a new random Uid.

Uid

public Uid(long hi,
           long lo)

Creates a new Uid with the given value.

This constructor is equivalent to UUID(long, long).

Parameters:

hi - the most significant bits of the new Uid.

lo - the least significant bits of the new Uid.

Uid

public Uid(byte[] bytes)

Uid

public Uid(String uidString)

Creates a new Uid instance from the encoded value in uidString.

This constructor is symmetric to the toString() method: The output of toString() can be passed to this constructor to create a new instance with the same value as (and thus being equal to) the first instance.

Parameters:

uidString - the string-encoded value of the Uid. Must not be null.

See Also:

toString()

Method Detail

valueOf

public static final Uid valueOf(byte[] bytes)

Creates a new Uid instance from the binary data in bytes.

If the given bytes is null or empty (array-length 0), this method returns null. Otherwise, it creates an instance using the Uid(byte[]) constructor.

Parameters:

bytes - the raw binary data of the Uid. May be null. If not null, its length must be exactly 0 (treated the same a null) or 16.

Returns:

an Uid instance created from the given bytes or null, if the input is null or empty (array-length 0).

valueOf

public static final Uid valueOf(String uidString)

Creates a new Uid instance from the encoded value in uidString.

If the given uidString is null or empty, this method returns null. Otherwise, it creates an instance using the Uid(String) constructor.

Parameters:

uidString - the string-encoded value of the Uid. May be null.

Returns:

an Uid instance created from the given uidString or null, if the input is null or empty.

toBytes

public byte[] toBytes()

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Gets a base64url-encoded string-representation of this Uid.

The string returned by this method can be passed to Uid(String) to create a new equal Uid instance.

Important: The string-representation is case-sensitive!

Inherited documentation:

Overrides:

toString in class Object

compareTo

public int compareTo(Uid other)

Specified by:

compareTo in interface Comparable<Uid>