org.josef.ejb

Class ValueObject

java.lang.Object

org.josef.ejb.ValueObject

All Implemented Interfaces:

Serializable, ValueObjectInterface

@Status(stage=TEST,
        unitTests=ABSENT)
public abstract class ValueObject
extends Object
implements ValueObjectInterface

Base class of all value objects.
Value objects, sometimes called Data Transfer Objects (DTO) are 'data objects with simple validation'. Value objects are normally passed between a client and an EJB Session Bean to increase performance. Without value objects getting a single field like name, address, zip or state, requires a remote method call. With value objects all of these fields can be fetched with a single remote method call.

Version:

1.0 $Revision: 6488 $

Author:

Martijn Baels, Kees Schotanus

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ValueObject() Default constructor that creates a value object with a null object Id and null version.
ValueObject(Long objectId, Integer version) Creates this value object using the supplied objectId and version.
ValueObject(ValueObject source) Copy constructor.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object object) Determines whether this object is equal to the supplied Object.
Long	getObjectId() Gets the object Id of this value object.
Integer	getVersion() Gets the version of this ValueObject.
int	hashCode() Computes the hash code of this Object.
String	toString() Creates a String representation of this ValueObject.
void	validate() Validates the state of this ValueObject.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.josef.ejb.ValueObjectInterface

copyFrom

Constructor Detail

ValueObject

public ValueObject()

Default constructor that creates a value object with a null object Id and null version.

ValueObject

public ValueObject(ValueObject source)
            throws InvalidStateException

Copy constructor.
Copies the content of the supplied source ValueObject into this ValueObject with the exception of objectId and version since these attributes are always set to null!

Parameters:

source - ValueObject whose value (data) is copied into this ValueObject.

Throws:

InvalidStateException - When at least one attribute in the source ValueObject is not valid.

NullPointerException - When the supplied source object is null.

ValueObject

public ValueObject(Long objectId,
                   Integer version)

Creates this value object using the supplied objectId and version.
You can only set the value for objectId and version in this constructor, no set...(...) methods exist for these attributes.

Parameters:

objectId - The object Id for the ValueObject.

version - The version for the ValueObject.

Method Detail

getObjectId

public Long getObjectId()

Gets the object Id of this value object.

Specified by:

getObjectId in interface ValueObjectInterface

Returns:

The unique object identifier (object Id).

getVersion

public Integer getVersion()

Gets the version of this ValueObject.

Specified by:

getVersion in interface ValueObjectInterface

Returns:

The version of this ValueObject.

validate

public void validate()
              throws InvalidStateException

Validates the state of this ValueObject.
This default implementation copies each individual field into itself. This should at least discover all fields that did not receive a value.

Specified by:

validate in interface ValueObjectInterface

Throws:

InvalidStateException - In case the state of this value object is not valid.
This could happen for example when mandatory fields are not set.

equals

public boolean equals(Object object)

Determines whether this object is equal to the supplied Object.
Both Objects are equal when:

• The supplied object is of type ValueObject
• The Object ID in both objects are equal (and non-null)

Overrides:

equals in class Object

Parameters:

object - The Object to compare to.
Objects not of type ValueObject will never be equal.

Returns:

True when both Objects are equal, false otherwise.

hashCode

public int hashCode()

Computes the hash code of this Object.
The hash code is 0 when this Object ID is null, otherwise it is equal to the hashCode of the Object ID.

Overrides:

hashCode in class Object

Returns:

Hash code of this Object.

toString

public String toString()

Creates a String representation of this ValueObject.

Overrides:

toString in class Object

Returns:

A String representation of this ValueObject.