net.sf.mmm.util.entity.api

Interface EntityId

All Superinterfaces:

AttributeReadValue<String>, Datatype, Serializable, SimpleDatatype<String>

All Known Implementing Classes:

AbstractEntityId, EntityIdImpl

public interface EntityId
extends SimpleDatatype<String>

This is the interface for an ID that uniquely identifies an object of a particular type. The referenced object is typically (but NOT strictly necessary) an entity.
An EntityId is build out of the following parts:

• object-id - unique ID of an object of a particular type.
• type-id - is the ID of the type of the object identified by this EntityId .
• revision - a object can potentially have multiple revisions (as history of changes). A EntityId uniquely identifies the specific revision.

Just like the primary key the revision and type of an object do not change. This allows to create an instance of the identified object without additional costs (e.g. database lookup) by a dynamic proxy using lazy loading.
An EntityId has a compact string representation that can be converted back to an EntityId. Therefore, the implementation shall provide a String-arg constructor.

Since:

3.0.0

Author:

Joerg Hohwiller (hohwille at users.sourceforge.net)

Field Summary

Fields

Modifier and Type	Field and Description
static long	OBJECT_ID_ILLEGAL An illegal value for the object-id.
static long	OBJECT_ID_MINIMUM_CUSTOM The minimum object-id that can be used for custom entities.
static int	RADIX This radix is used to convert numbers to/from strings.
static String	SEPARATOR the delimiter used in the string representations of an id
static char	SEPARATOR_CHAR The delimiter used in the string representations of an id.

Method Summary

Modifier and Type	Method and Description
long	getObjectId() This method gets the unique identifier of an entity (or any other object).
Number	getRevision() This method gets the number of the specific revision of the object referenced by this EntityId.
long	getTypeId() This method gets the identifier representing the type of the referenced entity or object.
String	toString() The string representation of the EntityId in the following form:

Methods inherited from interface net.sf.mmm.util.lang.api.SimpleDatatype

getValue

Field Detail

RADIX

static final int RADIX

This radix is used to convert numbers to/from strings.

See Also:

Constant Field Values

OBJECT_ID_ILLEGAL

static final long OBJECT_ID_ILLEGAL

An illegal value for the object-id. This is reserved for undefined values.

See Also:

Constant Field Values

OBJECT_ID_MINIMUM_CUSTOM

static final long OBJECT_ID_MINIMUM_CUSTOM

The minimum object-id that can be used for custom entities. All object-IDs lower than this are reserved for master-data entities provided with the application.
NOTE:
If you want to create a reusable and distributed extension for mmm please get in contact with us and we can try to find a reserved ID space.

See Also:

Constant Field Values

SEPARATOR_CHAR

static final char SEPARATOR_CHAR

The delimiter used in the string representations of an id.

See Also:

Constant Field Values

SEPARATOR

static final String SEPARATOR

the delimiter used in the string representations of an id

Method Detail

getObjectId

long getObjectId()

This method gets the unique identifier of an entity (or any other object).

Returns:

the object-id.

See Also:

GenericEntity.getId()

getTypeId

long getTypeId()

This method gets the identifier representing the type of the referenced entity or object. The type is typically directly related to the Class reflecting the object. However, in dynamically or mixed typed object-worlds (often used in content-management-systems) two instances of the same java Class may be considered to have different types that can only be determined at runtime. To resolve an EntityId a central component is required that can map the getTypeId() to the actual type (e.g. Class object) and vice versa.

Returns:

the classId.

getRevision

Number getRevision()

This method gets the number of the specific revision of the object referenced by this EntityId. If the associated object is NOT version controlled (e.g. a class or field), then the revision will always be null.
Further a revision of null always points to the latest revision of an object.

Returns:

the revision or null for the latest revision.

See Also:

RevisionedEntity.getRevision(), RevisionedEntity.LATEST_REVISION

toString

String toString()

The string representation of the EntityId in the following form:

 <objectId>.<typeId>[.<revision>]
 

The revision can be omitted if zero. All number values are encoded using the RADIX constant.
Returns the official String representation of this Datatype. While the general contract of Object.toString() is very weak and mainly used for debugging, the contract here is very strong. The returned String has to be suitable for end-users and official output to any kind of sink.
ATTENTION:
This method is not supposed to do internationalization (I18N). See NlsMessage for this purpose and implement NlsObject if you want to support I18N/L10N.

Specified by:

toString in interface Datatype

Overrides:

toString in class Object

Returns:

the official String representation to display the value of this Datatype.