org.cementj.base
Class ValueObject

java.lang.Object
  org.cementj.base.ValueObject

All Implemented Interfaces:

java.io.Serializable, Describable, DescribableAsXML

public abstract class ValueObject
extends java.lang.Object
implements java.io.Serializable, Describable, DescribableAsXML

Generic functionality for objects used to transfer data between objects. All VOs or value objects extending this class will have pre-built implementations of equals(), and hashcode(). In addition, these extended classes will have meaningful implementations of Describable and DescribableAsXML.

This class is named after the "Data Transfer Object" pattern. Some references use the term "Value Object" instead. They mean the same thing.

To keep VOs usable as distributed objects, it's recommended that they don't contain fields which aren't Serializable.

The implementations of equals() and hashcode() make extensions of this object automatically usable in HashMaps and Hashtables.

An example extension follows:

 public class CustomerVO extends ValueObject
{

  public CustomerVO() {}

  public String          getCustomerId()         {return _customerId;}
  public void            setCustomerId(String id)
  {
    if (id == null)  throw new IllegalArgumentException
                               ("Null customer Id not allowed.");
    if (id.equals(""))  throw new IllegalArgumentException
                                  ("Blank customer Id not allowed.");
    _customerId = id;
  }

  //  All other accessors and mutators omitted.

  private String          _customerId = null;
  private String          _firstName = null;
  private String          _lastName = null;
  private String          _address = null;
  private String          _city = null;
  private String          _state = null;
  private String          _zipCode = null;
}
 

Copyright: Delta Vortex Technologies, 2003.

See Also:

Serialized Form

Constructor Summary

protected

ValueObject()

Method Summary

java.lang.String	describe() Provides a textual version of description and state.
java.lang.String	describeAsXMLDocument() Provides XML Document Text for a given instance.
java.lang.String	describeAsXMLElement() Provides XML Element Text for a given instance.
java.lang.String	describeAsXMLElement(java.lang.String fieldName) Provides XML Element Text for a given instance.
java.lang.String	encodeAsXML()
boolean	equals(java.lang.Object obj)
java.lang.String	getReasonForNotEquals(java.lang.Object obj) Provides a textual reason that two ValueObjects are not equal.
int	hashCode()
protected void	init()
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

ValueObject

protected ValueObject()

Method Detail

init

protected void init()

hashCode

public int hashCode()

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object obj)

Overrides:

equals in class java.lang.Object

getReasonForNotEquals

public java.lang.String getReasonForNotEquals(java.lang.Object obj)

Provides a textual reason that two ValueObjects are not equal.

Parameters:

obj -

Returns:

text

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

describe

public java.lang.String describe()

Description copied from interface: Describable

Provides a textual version of description and state.

Specified by:

describe in interface Describable

encodeAsXML

public java.lang.String encodeAsXML()

describeAsXMLDocument

public java.lang.String describeAsXMLDocument()

Description copied from interface: DescribableAsXML

Provides XML Document Text for a given instance.

Specified by:

describeAsXMLDocument in interface DescribableAsXML

Returns:

XML Text

describeAsXMLElement

public java.lang.String describeAsXMLElement()

Description copied from interface: DescribableAsXML

Provides XML Element Text for a given instance.

Specified by:

describeAsXMLElement in interface DescribableAsXML

Returns:

XML Text

describeAsXMLElement

public java.lang.String describeAsXMLElement(java.lang.String fieldName)

Description copied from interface: DescribableAsXML

Provides XML Element Text for a given instance.

Specified by:

describeAsXMLElement in interface DescribableAsXML

Returns:

XML Text