org.jquantlib.util

Class LazyObject

java.lang.Object

org.jquantlib.util.LazyObject

All Implemented Interfaces:

Observable, Observer

Direct Known Subclasses:

Instrument, PiecewiseYieldCurve

public abstract class LazyObject
extends java.lang.Object
implements Observer, Observable

Framework for calculation on demand and result caching.

See Also:

Lazy Object Design Pattern, Observer, Observable

Constructor Summary

Constructors

Constructor and Description
LazyObject() Creates a new LazyObject instance which is potentially able to perform calculations on demand every time it observes a change in a Observable object.

Method Summary

Modifier and Type	Method and Description
void	addObserver(Observer observer) Attaches a observer to the Observable.
int	countObservers() Counts how many Observers were attached to this class.
void	deleteObserver(Observer observer) Detaches a previously attached observer to the observable.
void	deleteObservers() Detaches all previously attached observer to the observable.
void	freeze() This method constrains the object to return the presently cached results on successive invocations, even if arguments upon which they depend should change.
java.util.List<Observer>	getObservers() Returns list of observers registered with the Observable.
void	notifyObservers() Notifies all attached observers about changes in the observable.
void	notifyObservers(java.lang.Object arg) Notifies all attached observers about changes in the observable.
void	recalculate() This method force the recalculation of any results which would otherwise be cached.
void	unfreeze() This method reverts the effect of the freeze method, thus re-enabling recalculations.
void	update() This method is called whenever the observed object is changed.

Methods inherited from class java.lang.Object

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

Constructor Detail

LazyObject

public LazyObject()

Creates a new LazyObject instance which is potentially able to perform calculations on demand every time it observes a change in a Observable object. A LazyObject is an Observer and an Observable at the same time.

Method Detail

recalculate

public final void recalculate()

This method force the recalculation of any results which would otherwise be cached.

freeze

public final void freeze()

This method constrains the object to return the presently cached results on successive invocations, even if arguments upon which they depend should change.

unfreeze

public final void unfreeze()

This method reverts the effect of the freeze method, thus re-enabling recalculations.

update

public void update()

Description copied from interface: Observer

This method is called whenever the observed object is changed.

Specified by:

update in interface Observer

addObserver

public final void addObserver(Observer observer)

Description copied from interface: Observable

Attaches a observer to the Observable. After attachment the observer gets informed about changes in the Observable.

Specified by:

addObserver in interface Observable

Parameters:

observer - The observer to attach to the observable

countObservers

public final int countObservers()

Description copied from interface: Observable

Counts how many Observers were attached to this class.

Specified by:

countObservers in interface Observable

Returns:

the number of Observers

See Also:

Observer

deleteObserver

public final void deleteObserver(Observer observer)

Description copied from interface: Observable

Detaches a previously attached observer to the observable. After detachment the observer does no longer receive change notifications from the observable.

Specified by:

deleteObserver in interface Observable

Parameters:

observer - The observer to detach from the observable

notifyObservers

public final void notifyObservers()

Description copied from interface: Observable

Notifies all attached observers about changes in the observable.

Specified by:

notifyObservers in interface Observable

notifyObservers

public final void notifyObservers(java.lang.Object arg)

Description copied from interface: Observable

Notifies all attached observers about changes in the observable.

Specified by:

notifyObservers in interface Observable

Parameters:

arg - an arbitrary Object to be passed to the Observer

deleteObservers

public final void deleteObservers()

Description copied from interface: Observable

Detaches all previously attached observer to the observable. After detachment observers do not longer receive change notifications from the observable.

Specified by:

deleteObservers in interface Observable

getObservers

public final java.util.List<Observer> getObservers()

Description copied from interface: Observable

Returns list of observers registered with the Observable. List returned is unmodifiable list.

Specified by:

getObservers in interface Observable

Returns:

list of observers