ca.odell.glazedlists.calculation

Class AbstractEventListCalculation<N,E>

java.lang.Object

ca.odell.glazedlists.calculation.AbstractCalculation<N>

ca.odell.glazedlists.calculation.AbstractEventListCalculation<N,E>

All Implemented Interfaces:

Calculation<N>, ListEventListener<E>, java.util.EventListener

public abstract class AbstractEventListCalculation<N,E>
extends AbstractCalculation<N>
implements ListEventListener<E>

The transition between an EventList and a single calculated value based on information from each element of the EventList happens in subclasses of this class. To ease the job of maintaining the value of the Calculation when the backing EventList changes, this abstract class provides three abstract methods which must be implemented:

• inserted(E) updates the value of this Calculation to include the inserted element
• deleted(E) updates the value of this Calculation to exclude the deleted element
• updated(E, E) updates the value of this Calculation to include the replacement element and exclude the prior element

Author:

James Lemieux

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AbstractEventListCalculation(N initialValue, EventList<E> source)

Method Summary

Modifier and Type	Method and Description
protected abstract void	deleted(E oldElement) Updates the value of this Calculation to exclude the information from the oldElement.
void	dispose() Releases the resources consumed by this AbstractEventListCalculation so that it may eventually be garbage collected.
protected abstract void	inserted(E newElement) Updates the value of this Calculation to include the information from the newElement.
void	listChanged(ListEvent<E> listChanges) Updates the value of this Calculation in response to the listChanges.
protected abstract void	updated(E oldElement, E newElement) Updates the value of this Calculation to exclude the information from the oldElement and include the information from the newElement.

Methods inherited from class ca.odell.glazedlists.calculation.AbstractCalculation

addPropertyChangeListener, fireValueChange, getName, getValue, removePropertyChangeListener, setName, setValue

Methods inherited from class java.lang.Object

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

Constructor Detail

AbstractEventListCalculation

protected AbstractEventListCalculation(N initialValue,
                                       EventList<E> source)

Parameters:

initialValue - the value that should immediately be reported as the value of this Calculation

source - the List of elements from which this calculation is derived

Method Detail

dispose

public void dispose()

Releases the resources consumed by this AbstractEventListCalculation so that it may eventually be garbage collected.

An AbstractEventListCalculation will be garbage collected without a call to dispose(), but not before its source EventList is garbage collected. By calling dispose(), you allow the AbstractEventListCalculation to be garbage collected before its source EventList. This is necessary for situations where an AbstractEventListCalculation is short-lived but its source EventList is long-lived.

Specified by:

dispose in interface Calculation<N>

inserted

protected abstract void inserted(E newElement)

Updates the value of this Calculation to include the information from the newElement.

Parameters:

newElement - the new element within the EventList

deleted

protected abstract void deleted(E oldElement)

Updates the value of this Calculation to exclude the information from the oldElement.

Parameters:

oldElement - the old element within the EventList

updated

protected abstract void updated(E oldElement,
                                E newElement)

Updates the value of this Calculation to exclude the information from the oldElement and include the information from the newElement.

Parameters:

oldElement - the old element within the EventList

newElement - the new element which replaced the oldElement

listChanged

public void listChanged(ListEvent<E> listChanges)

Updates the value of this Calculation in response to the listChanges.

Specified by:

listChanged in interface ListEventListener<E>

Parameters:

listChanges - describes the changes to the backing EventList