Type Parameters:

E - type of the identified entity.

All Known Implementing Classes:

AbstractId, AbstractInstantId, AbstractVersionId, LongInstantId, LongVersionId, StringInstantId, StringVersionId, UuidInstantId, UuidVersionId
```
public interface Id<E>
```
This is the interface for an ID that uniquely identifies a persistent entity of a particular type (<E>).
An Id is build out of the following parts:
- object-id - the primary key that identifies the entity and is unique for a specific type.
- type - is the (optional) type of the identified entity.
- version - the optional version (revision) of the entity.
Just like the primary key the version and type of an object do not change. This allows to use the Id as globally unique identifier for its corresponding entity.
An Id has a compact string representation that can be converted back to an Id. Therefore, the implementation shall provide a String-arg constructor and a static valueOf(String) method.
Since:

1.0.0

See Also:

AbstractId

Field Summary

Fields
Modifier and Type	Field	Description
`static String`	`PROPERTY_ID`	The name of the `ID` property (e.g.
`static String`	`PROPERTY_VERSION`	The name of the `version` property (e.g.
`static Comparable<?>`	`VERSION_LATEST`	The value used as `version` if it unspecified.
`static char`	`VERSION_SEPARATOR`	The separator for the `version`.

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`Object`	`getId()`
`default String`	`getIdAsString()`
`Class<E>`	`getType()`
`Comparable<?>`	`getVersion()`
`default String`	`getVersionAsString()`
`static <E extends Entity> Id<E>`	`of(E entity)`	Type-safe and `null`-safe variant of `Entity.getId()`.
`String`	`toString()`
`Id<E>`	`withLatestVersion()`
`Id<E>`	`withType(Class<?> type)`

- Field Detail
  - PROPERTY_ID
```
static final String PROPERTY_ID
```
    The name of the ID property (e.g. for JSON or XML).
    
    See Also:
    
    Constant Field Values
  - PROPERTY_VERSION
```
static final String PROPERTY_VERSION
```
    The name of the version property (e.g. for JSON or XML).
    
    See Also:
    
    Constant Field Values
  - VERSION_LATEST
```
static final Comparable<?> VERSION_LATEST
```
    The value used as version if it unspecified. If you are using an Id as link to an Entity you will use this value to point to the recent version of the Entity.
  - VERSION_SEPARATOR
```
static final char VERSION_SEPARATOR
```
    The separator for the version.
    
    See Also:
    
    Constant Field Values
- Method Detail
  - getId
```
Object getId()
```
    Returns:
    
    the primary key of the identified Entity as Object value. It is only unique for a particular type of an entity.
    
    See Also:
    
    LongVersionId, UuidVersionId, StringVersionId
  - getIdAsString
```
default String getIdAsString()
```
    Returns:
    
    the primary key as String for marshalling.
  - getType
```
Class<E> getType()
```
    Returns:
    
    the Class reflecting the type of the referenced entity. May be null if not available.
  - withType
```
Id<E> withType(Class<?> type)
```
    Parameters:
    
    type - the new value of getType(). Exact type should actually be Class<E> but this prevents simple usage. As the type can not actually be changed with this method, this should be fine.
    
    Returns:
    
    a copy of this Id with the given type or this Id itself if already satisfying.
  - withLatestVersion
```
Id<E> withLatestVersion()
```
    Returns:
    
    a copy of this Id with a version of VERSION_LATEST e.g. to use the Id as regular foreign key (pointing to the latest revision and not a historic revision) or this Id itself if already satisfying.
  - getVersion
```
Comparable<?> getVersion()
```
    Returns:
    
    the version of this entity. Whenever the Entity gets updated (a modification is saved and the transaction is committed), this version is increased. Typically the version is a Number starting with 0 for a new Entity that is increased whenever a modification is committed. However, it may also be an Instant. The version acts as a modification sequence for optimistic locking. On each update it will be verified that the version has not been increased already by another transaction. When linking an Entity (Id used as foreign key) the version can act as revision for auditing. If it is VERSION_LATEST (null) it points to the latest revision of the Entity. Otherwise it points to a specific historic revision of the Entity. Depending on the database technology (e.g. when using hibernate envers) the version and the revision can be semantically different. In such case a primary key can not be converted 1:1 as revisioned foreign key Id.
  - getVersionAsString
```
default String getVersionAsString()
```
    Returns:
    
    the version as String for marshalling.
  - toString
```
String toString()
```
    Overrides:
    
    toString in class Object
    
    Returns:
    
    the String representation of this Id. Will consist of object-id, type and revision separated with a specific separator. Segments that are null will typically be omitted in the String representation.
  - of
```
static <E extends Entity> Id<E> of(E entity)
```
    Type-safe and null-safe variant of Entity.getId().
    
    Type Parameters:
    
    E - type of Entity.
    
    Parameters:
    
    entity - the Entity.
    
    Returns:
    
    the Id of the given Entity. Will be null if the given Entity was null or it's ID is null.
    
    See Also:
    
    Entity.getId()

Interface Id<E>

Field Summary

Method Summary

Field Detail

PROPERTY_ID

PROPERTY_VERSION

VERSION_LATEST

VERSION_SEPARATOR

Method Detail

getId

getIdAsString

getType

withType

withLatestVersion

getVersion

getVersionAsString

toString

of