Class java.util.Observable
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Class java.util.Observable

java.lang.Object
   |
   +----java.util.Observable

public class Observable
extends Object
This class should be subclassed by observable object, or "data" in the Model-View paradigm. An Observable object may have any number of Observers. Whenever the Observable instance changes, it notifies all of its observers. Notification is done by calling the update() method on all observers.

Constructor Index

 o Observable()

Method Index

 o addObserver(Observer)
Adds an observer to the observer list.
 o clearChanged()
Clears an observable change.
 o countObservers()
Counts the number of observers.
 o deleteObserver(Observer)
Deletes an observer from the observer list.
 o deleteObservers()
Deletes observers from the observer list.
 o hasChanged()
Returns a true boolean if an observable change has occurred.
 o notifyObservers()
Notifies all observers if an observable change occurs.
 o notifyObservers(Object)
Notifies all observers of the specified observable change which occurred.
 o setChanged()
Sets a flag to note an observable change.

Constructors

 o Observable
  public Observable()

Methods

 o addObserver
  public synchronized void addObserver(Observer o)
Adds an observer to the observer list.
Parameters:
o - the observer to be added
 o deleteObserver
  public synchronized void deleteObserver(Observer o)
Deletes an observer from the observer list.
Parameters:
o - the observer to be deleted
 o notifyObservers
  public void notifyObservers()
Notifies all observers if an observable change occurs.
 o notifyObservers
  public synchronized void notifyObservers(Object arg)
Notifies all observers of the specified observable change which occurred.
Parameters:
arg - what is being notified
 o deleteObservers
  public synchronized void deleteObservers()
Deletes observers from the observer list.
 o setChanged
  protected synchronized void setChanged()
Sets a flag to note an observable change.
 o clearChanged
  protected synchronized void clearChanged()
Clears an observable change.
 o hasChanged
  public synchronized boolean hasChanged()
Returns a true boolean if an observable change has occurred.
 o countObservers
  public synchronized int countObservers()
Counts the number of observers.

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