oracle.ifs.common

Class UncachedSelectorCollection

java.lang.Object

oracle.ifs.common.UncachedSelectorCollection

All Implemented Interfaces:

Collection, IfsEventHandler

public class UncachedSelectorCollection
extends Object
implements Collection

An UncachedSelectorCollection is a Collection whose items are LIBRARYOBJECTs specified by a Selector or S_Selector and not cached by the collection.

By not caching its items, an UncachedSelectorCollection maintains a small memory footprint. However, each use of the collection causes a database roundtrip, making UncachedSelectorCollection less performant than CachedSelectorCollection.

The order of items returned by getItems() and getItemsVector() is determined by the sort specification of the Selector or S_Selector. The method getItems(int) is implemented in terms of getItems(). For best performance in iterating over the items of the collection, call getItems() once instead of getItems(int) repeatedly.

The LIBRARYOBJECTs returned by the Selector or S_Selector must have a Name attribute. Use getItems(String) to look up an item by name. This lookup is case-insentive. If more than one item has the same case-insensitive name, getItems(String) returns an arbitrary item with that name.

The performance of getItems(String) can be improved by enabling a mini-cache of the "n" items most-recently returned by this method. The size of this mini-cache is specified by a constructor argument.

Version:

1.0

Author:

David Pitfield

(Published)

Field Summary

Fields

Modifier and Type	Field and Description
protected Class	m_Class The class of the objects in this Collection.
protected int	m_ItemCount The number of items in this collection, or -1 if unknown.
protected int	m_MaximumRecentItems The maximum length of m_RecentItems.
protected String	m_NameExpression The SQL expression for the specified Selector or S_Selector that evaluates to the uppercase name of the item.
protected oracle.ifs.common.UncachedSelectorCollection.ItemLink	m_RecentItems A linked list of the "n" items most recently returned by getItems(String), with the most recent at the head and the least recent at the tail of the list.
protected Selector	m_Selector The Selector used to obtain the items in this Collection (if this is a collection of LibraryObjects).
protected S_Selector	m_SSelector The S_Selector used to obtain the items in this Collection (if this is a collection of S_LibraryObjects).

Constructor Summary

Constructors

Constructor and Description
UncachedSelectorCollection(S_Selector selector, String nameExpression, String className, int maximumRecentItems) Constructs a collection of S_LibraryObjects.
UncachedSelectorCollection(Selector selector, String nameExpression, String className, int maximumRecentItems) Constructs a collection of LibraryObjects.

Method Summary

Modifier and Type	Method and Description
Object	checkItemByUpperCaseName(String upperCaseName) Gets the specified item in this Collection by uppercase name, and returns null if not found.
Object	getItemByUpperCaseName(String upperCaseName) Gets the specified item in this Collection by uppercase name.
int	getItemCount() Gets the number of items in this Collection.
Object[]	getItems() Gets an array containing the items in this Collection.
Object	getItems(int index) Gets the specified item in this Collection.
Object	getItems(String name) Gets the specified item in this Collection.
Vector	getItemsVector() Gets a vector containing the items in this Collection.
void	handleEvent(IfsEvent event) Handles the specified event.
void	reset() Resets this Collection.
protected void	resolve() Ensures the items in this Collection are resolved.

Methods inherited from class java.lang.Object

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

Field Detail

m_Class

protected Class m_Class

The class of the objects in this Collection.

The value returned by getItems() can be cast to an array of this type.

(Unpublished)

m_SSelector

protected S_Selector m_SSelector

The S_Selector used to obtain the items in this Collection (if this is a collection of S_LibraryObjects).

(Unpublished)

m_Selector

protected Selector m_Selector

The Selector used to obtain the items in this Collection (if this is a collection of LibraryObjects).

(Unpublished)

m_NameExpression

protected String m_NameExpression

The SQL expression for the specified Selector or S_Selector that evaluates to the uppercase name of the item.

(Unpublished)

m_ItemCount

protected int m_ItemCount

The number of items in this collection, or -1 if unknown.

(Unpublished)

m_RecentItems

protected oracle.ifs.common.UncachedSelectorCollection.ItemLink m_RecentItems

A linked list of the "n" items most recently returned by getItems(String), with the most recent at the head and the least recent at the tail of the list.

(Unpublished)

m_MaximumRecentItems

protected int m_MaximumRecentItems

The maximum length of m_RecentItems.

(Unpublished)

Constructor Detail

UncachedSelectorCollection

public UncachedSelectorCollection(S_Selector selector,
                                  String nameExpression,
                                  String className,
                                  int maximumRecentItems)
                           throws IfsException

Constructs a collection of S_LibraryObjects.

Parameters:

selector - the S_Selector used to obtain the items in the Collection

nameExpression - the SQL expression for the S_Selector that evaluates to the uppercased name of an item

className - the full classname of the objects in this Collection; must be S_LibraryObject or a subclass of S_LibraryObject; if null, S_LibraryObject is used

maximumRecentItems - the maximum number of items recently returned by getItems(String) to cache; typical values are 1 to 50, or 0 to disable caching

Throws:

IfsException - (IFS-12210) if the operation fails

(Unpublished)

UncachedSelectorCollection

public UncachedSelectorCollection(Selector selector,
                                  String nameExpression,
                                  String className,
                                  int maximumRecentItems)
                           throws IfsException

Constructs a collection of LibraryObjects.

Parameters:

selector - the Selector used to obtain the items in the Collection

nameExpression - the SQL expression for the Selector that evaluates to the uppercased name of an item

className - the full classname of the objects in this Collection; must be LibraryObject or a subclass of LibraryObject; if null, LibraryObject is used

maximumRecentItems - the maximum number of items recently returned by getItems(String) to cache; typical values are 1 to 50, or 0 to disable caching

Throws:

IfsException - (IFS-12210) if the operation fails

(Unpublished)

Method Detail

getItemCount

public int getItemCount()
                 throws IfsException

Gets the number of items in this Collection.

Specified by:

getItemCount in interface Collection

Returns:

the number of items in this Collection

Throws:

IfsException - (IFS-12211) if the operation fails

(Published)

getItems

public Object[] getItems()
                  throws IfsException

Gets an array containing the items in this Collection.

Specified by:

getItems in interface Collection

Returns:

the items in this Collection

Throws:

IfsException - (IFS-12212) if the operation fails

(Published)

getItems

public Object getItems(int index)
                throws IfsException

Gets the specified item in this Collection.

Specified by:

getItems in interface Collection

Parameters:

index - the zero-based index of the item

Returns:

the item

Throws:

IfsException - (IFS-12213) if the operation fails

(Published)

getItems

public Object getItems(String name)
                throws IfsException

Gets the specified item in this Collection.

Specified by:

getItems in interface Collection

Parameters:

name - the name of the item

Returns:

the item

Throws:

IfsException - (IFS-12214) if the operation fails

(Published)

getItemByUpperCaseName

public Object getItemByUpperCaseName(String upperCaseName)
                              throws IfsException

Gets the specified item in this Collection by uppercase name.

Specified by:

getItemByUpperCaseName in interface Collection

Parameters:

upperCaseName - the name of the item

Returns:

the item

Throws:

IfsException - (IFS-12214) if the operation fails

(Unpublished)

checkItemByUpperCaseName

public Object checkItemByUpperCaseName(String upperCaseName)
                                throws IfsException

Gets the specified item in this Collection by uppercase name, and returns null if not found.

Specified by:

checkItemByUpperCaseName in interface Collection

Parameters:

upperCaseName - the name of the item

Returns:

the item, or null if not found

Throws:

IfsException - (IFS-12214) if the operation fails

(Unpublished)

getItemsVector

public Vector getItemsVector()
                      throws IfsException

Gets a vector containing the items in this Collection.

The order of the items in the vector is identical to the order of the items in the array returned by getItems().

Specified by:

getItemsVector in interface Collection

Returns:

a vector containing the items in this Collection

Throws:

IfsException - (IFS-12215) if the operation fails

(Published)

reset

public void reset()
           throws IfsException

Resets this Collection.

Resetting a Collection causes the items in it to be redetermined.

Specified by:

reset in interface Collection

Throws:

IfsException - (IFS-12216) if the operation fails

(Unpublished)

resolve

protected final void resolve()
                      throws IfsException

Ensures the items in this Collection are resolved.

Throws:

IfsException - (IFS-12201) if the operation fails

(Unpublished)

handleEvent

public void handleEvent(IfsEvent event)
                 throws IfsException

Handles the specified event. This results in the Collection being reset.

Specified by:

handleEvent in interface IfsEventHandler

Parameters:

event - the event

Throws:

IfsException - if the operation fails

(Published)