net.sf.mmm.util.entity.base

Class AbstractGenericEntity<ID>

java.lang.Object

net.sf.mmm.util.entity.base.AbstractGenericEntity<ID>

Type Parameters:

ID - is the type of the primary key.

All Implemented Interfaces:

Serializable, Entity, GenericEntity<ID>, MutableGenericEntity<ID>, AttributeReadId<ID>

Direct Known Subclasses:

AbstractRevisionedEntity

public abstract class AbstractGenericEntity<ID>
extends Object
implements MutableGenericEntity<ID>

This is the abstract base-class that implementations of MutableGenericEntity should inherit from (if possible).

Author:

Joerg Hohwiller (hohwille at users.sourceforge.net)

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
private ID	id
private int	modificationCounter
private static long	serialVersionUID UID for serialization.

Constructor Summary

Constructors

Constructor and Description
AbstractGenericEntity() The constructor.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
ID	getId() This method gets the unique identifier (primary key) of this entity.
int	getModificationCounter() This method gets the current modification-counter of this entity.
int	hashCode()
void	setId(ID id) This method sets the ID of this entity.
void	setModificationCounter(int version) This method sets the modification counter of this entity.
protected void	toString(StringBuilder buffer) Method to extend Object.toString() logic.

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

UID for serialization.

See Also:

Constant Field Values

id

private ID id

See Also:

getId()

modificationCounter

private int modificationCounter

See Also:

getModificationCounter()

Constructor Detail

AbstractGenericEntity

public AbstractGenericEntity()

The constructor.

Method Detail

getId

public ID getId()

This method gets the unique identifier (primary key) of this entity. While this method is initially defined in a generic way, it is strongly recommended to use Long as datatype for IDs.
Even if you want to have a String-based business-oriented identifier it is best practice to use a Long as primary key and add the business identifier as additional field (with a unique constraint). This way references to the entity will be a lot more compact and improve your performance in JOINs or the like. However, there may be reasons to use other datatypes for the ID. In any case the unique ID should be an immutable java-object that can be rebuild from its string-representation.
Please note that if your ID has a specific syntax, semantic, formatting rules, etc. you should create a custom Datatype for it. If it can easily be mapped to a Long value you can still use Long here and provide a transient getter method that returns the your custom Datatype from the Long.

Specified by:

getId in interface GenericEntity<ID>

Specified by:

getId in interface AttributeReadId<ID>

Returns:

the ID of this entity. It may be null if the object is new and no ID has manually been assigned.

setId

public void setId(ID id)

This method sets the ID of this entity.
ATTENTION:
This operation should only be used in specific cases and if you are aware of what you are doing. Typically the ID is a GeneratedValue and therefore managed by the persistence. However, for final freedom we decided to add this method to the API (e.g. to copy from transfer-object to persistent-entity and vice-versa).

Specified by:

setId in interface MutableGenericEntity<ID>

Parameters:

id - is the new value of GenericEntity.getId().

getModificationCounter

public int getModificationCounter()

This method gets the current modification-counter of this entity. Whenever the object gets modified and saved, this counter will be increased. The initial value after construction is 0.
If this feature is NOT supported for some reason, this method should always return 0.

Specified by:

getModificationCounter in interface GenericEntity<ID>

Returns:

the current modification-counter.

See Also:

Version

setModificationCounter

public void setModificationCounter(int version)

This method sets the modification counter of this entity.
ATTENTION:
This operation should only be used in specific cases and if you are aware of what you are doing as this attribute is managed by the persistence. However, for final freedom we decided to add this method to the API (e.g. to copy from transfer-object to persistent-entity and vice-versa).

Specified by:

setModificationCounter in interface MutableGenericEntity<ID>

Parameters:

version - is the new value of GenericEntity.getModificationCounter().

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

protected void toString(StringBuilder buffer)

Method to extend Object.toString() logic.

Parameters:

buffer - is the StringBuilder where to append the string representation.