bill.util.persist
Class EntityCollection

java.lang.Object
  |
  +--bill.util.persist.EntityCollection

Direct Known Subclasses:

EntityCollectionConfig, EntityCollectionRDBMS

public abstract class EntityCollection

extends Object

Holds a collection of related entities. Used for 'queries' that retrieve multiple entities of the same type (i.e. Users, Cars, Trucks, etc).

Field Summary

protected Hashtable	_criteria
protected Vector	_entities
protected String	_entityName
protected EntityData	_sampleEntity Sample EntityData of the type contained in the list.

Constructor Summary

EntityCollection()
Default creator, normally only used when creating an object via introspection.

EntityCollection(String entityName, Hashtable criteria)
Main creator, takes the selection criteria for populating the entity collection as input.

Method Summary

protected EntityData	createSampleEntity() Creates an instance of the entity that is contained in this collecion.
Hashtable	getCriteria() Retrieves the selection criteria used to populate the entity colleciton.
Vector	getEntities() Retrieves the list of entities that make up the collection.
EntityData	getEntity(int index) Retrieve a specific entity from the collection.
String	getEntityName() Gets the class name of the entities that are contained in this collection.
abstract void	populateCollection() Must be implemented by the subclass, this is the method that actually performs the read from the persistent data store and populates the collection with it's entities.
void	save() Loops through all the entities in the collection and calls their save method so they are updated in the persistent store.
void	setAllDeleted() Marks all entities in the collection as deleted.
void	setCriteria(Hashtable criteria) Sets the selection criteria used to populate the entity colleciton.
void	setEntityName(String entityName) Sets the class name of the entity that is contained in this collection.
int	size() Returns the number of entities contained in this collection.

Methods inherited from class java.lang.Object

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

Field Detail

_entityName

protected String _entityName

_entities

protected Vector _entities

_criteria

protected Hashtable _criteria

_sampleEntity

protected EntityData _sampleEntity

Sample EntityData of the type contained in the list. Needed so we know details about the entity such as its elements.

Constructor Detail

EntityCollection

public EntityCollection()

Default creator, normally only used when creating an object via introspection. When an object is created using this creator, the setEntityName and setCriteria must be called as well to complete the setting of the data required by this class.

EntityCollection

public EntityCollection(String entityName,
                        Hashtable criteria)
                 throws PersistException

Main creator, takes the selection criteria for populating the entity collection as input.

Parameters:

entityName - Name of the entity that is contained in this collection. Must match the entitiy's Java class name as we will use introspection to create one. Use the full package name if neccessary, such as com.mycompany.UserData.

criteria - The criteria to use to populate the entity collection. Keyed by the element name, the result is the element value.

Method Detail

setEntityName

public void setEntityName(String entityName)
                   throws PersistException

Sets the class name of the entity that is contained in this collection. Also creates a sample entity of that entity name.

Parameters:

entityName - Value to set the entity name to.

Throws:

PersistException - Thrown when a sample entity cannot be created.

getEntityName

public String getEntityName()

Gets the class name of the entities that are contained in this collection.

Returns:

The class name of the entities.

setCriteria

public void setCriteria(Hashtable criteria)

Sets the selection criteria used to populate the entity colleciton.

Parameters:

criteria - The cirteria to use to populate the entity collection. Keyed by the element name, the result is the element value.

getCriteria

public Hashtable getCriteria()

Retrieves the selection criteria used to populate the entity colleciton.

Returns:

The selection criteria.

getEntities

public Vector getEntities()

Retrieves the list of entities that make up the collection.

Returns:

The collection's entities.

getEntity

public EntityData getEntity(int index)

Retrieve a specific entity from the collection.

Parameters:

index - The index of the entity to be retrieved, this is a 0 based index.

setAllDeleted

public void setAllDeleted()

Marks all entities in the collection as deleted. If the collection is then save (or if an item in the collection is saved), the entities will then be deleted from their persistent store.

save

public void save()
          throws PersistException

Loops through all the entities in the collection and calls their save method so they are updated in the persistent store.

Throws:

PersistException - Thrown when the save method fails, forwards on the exception from the save method.

See Also:

EntityData.save()

createSampleEntity

protected EntityData createSampleEntity()
                                 throws PersistException

Creates an instance of the entity that is contained in this collecion. We create most of the entities in the collection via introspection, and this is the method that does this.

Returns:

A newly created instance of the entity.

Throws:

PersistException - Thrown when we cannot instantiate the new entity object.

size

public int size()

Returns the number of entities contained in this collection.

Returns:

The number of entities.

populateCollection

public abstract void populateCollection()
                                 throws PersistException

Must be implemented by the subclass, this is the method that actually performs the read from the persistent data store and populates the collection with it's entities.