com.softwareag.mobile.runtime.toolkit.util

Class Observable

java.lang.Object

com.softwareag.mobile.runtime.toolkit.util.Observable

Direct Known Subclasses:

AbstractListViewDatasource

public class Observable
extends java.lang.Object

This class represents an observable object, or "data" in the model-view paradigm. It can be subclassed to represent an object that the application wants to have observed. After an observable instance changes, an application calling the Observable's notifyObservers method causes all of its observers to be notified of the change by a call to their update method.

Version:

9.6.0.0000-0237

Constructor Summary

Constructors

Constructor and Description
Observable() Creates a new instance without registered observers.

Method Summary

Methods

Modifier and Type	Method and Description
void	addObserver(Observer observer) Adds an observer to the set of observers for this object, provided that it is not the same as some observer already in the set
int	countObservers() Returns the number of observers of this Observable object.
void	deleteObserver(Observer observer) Deletes an observer from the set of observers of this object.
void	deleteObservers() Clears the observer list so that this object no longer has any observers.
boolean	hasChanged() Tests if this object has changed.
void	notifyObservers() This method is equivalent to notifyObservers(null, false)
void	notifyObservers(java.lang.Object object) If this object has changed, as indicated by the hasChanged method, then notify all of its observers and then call the clearChanged method to indicate that this object has no longer changed.
void	notifyObservers(java.lang.Object object, boolean setChanged) This method is a shortcut to change the object changed status and call the notification method.

Methods inherited from class java.lang.Object

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

Constructor Detail

Observable

public Observable()

Creates a new instance without registered observers.

Method Detail

notifyObservers

public void notifyObservers()

This method is equivalent to notifyObservers(null, false)

notifyObservers

public void notifyObservers(java.lang.Object object)

If this object has changed, as indicated by the hasChanged method, then notify all of its observers and then call the clearChanged method to indicate that this object has no longer changed.

notifyObservers

public void notifyObservers(java.lang.Object object,
                   boolean setChanged)

This method is a shortcut to change the object changed status and call the notification method.

addObserver

public void addObserver(Observer observer)

Adds an observer to the set of observers for this object, provided that it is not the same as some observer already in the set

Parameters:

observer - an observer to be added.

deleteObserver

public void deleteObserver(Observer observer)

Deletes an observer from the set of observers of this object. Passing null to this method will have no effect.

Parameters:

observer - the observer to be deleted.

deleteObservers

public void deleteObservers()

Clears the observer list so that this object no longer has any observers.

countObservers

public int countObservers()

Returns the number of observers of this Observable object.

Returns:

the number of observers of this object.

hasChanged

public boolean hasChanged()

Tests if this object has changed.

Returns:

true if and only if the setChanged method has been called more recently than the clearChanged method on this object; false otherwise.