Apache Derby Database Engine and Embedded JDBC Driver 10.17.1.0 · org.apache.derby.iapi.services.monitor.DerbyObservable

Modifier and Type	Field and Description
private boolean	_hasChanged
private ArrayList<DerbyObserver>	_observers

Access	Constructor and Description
public	DerbyObservable() No-arg constructor

Method Summary

Modifier and Type	Method and Description
public synchronized void	addObserver(DerbyObserver The object which wants to be notified when this object changes observer) Add another observer who wants to be told about changes to this object.
public synchronized int	Returns: The number of watchers countObservers() Return the number of observers who are watching this object.
public synchronized void	deleteObserver(DerbyObserver The observer to remove. observer) Remove a specific observer from the list of watchers.
public void	notifyObservers() This method is equivalent to notifyObservers(null);
public void	notifyObservers(Object Extra information to be passed to the observer's callback method. extraInfo) If this object has changed, then notify all observers.
protected synchronized void	setChanged() When the object state changes, the object calls this method in order to flag that fact.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll toString wait wait wait

_hasChanged	back to summary
private boolean _hasChanged

_observers	back to summary
private ArrayList<DerbyObserver> _observers

DerbyObservable	back to summary
public DerbyObservable() No-arg constructor

addObserver	back to summary
public synchronized void addObserver(DerbyObserver observer) Add another observer who wants to be told about changes to this object. Parameters observer:DerbyObserver The object which wants to be notified when this object changes Exceptions IllegalArgumentException: If the argument is bad (e.g., null)

addObserver

public synchronized void addObserver(DerbyObserver observer)

Add another observer who wants to be told about changes to this object.

Parameters

observer:DerbyObserver: The object which wants to be notified when this object changes

Exceptions

countObservers	back to summary
public synchronized int countObservers() Return the number of observers who are watching this object. Returns:int The number of watchers

countObservers

public synchronized int countObservers()

Return the number of observers who are watching this object.

deleteObserver	back to summary
public synchronized void deleteObserver(DerbyObserver observer) Remove a specific observer from the list of watchers. Null is ignored. Parameters observer:DerbyObserver The observer to remove.

deleteObserver

public synchronized void deleteObserver(DerbyObserver observer)

Remove a specific observer from the list of watchers. Null is ignored.

Parameters

notifyObservers	back to summary
public void notifyObservers() This method is equivalent to notifyObservers(null);

notifyObservers	back to summary
public void notifyObservers(Object extraInfo) If this object has changed, then notify all observers. Pass them this object and the extraInfo. This object is then marked as unchanged again. Parameters extraInfo:Object Extra information to be passed to the observer's callback method.

notifyObservers

public void notifyObservers(Object extraInfo)

If this object has changed, then notify all observers. Pass them this object and the extraInfo. This object is then marked as unchanged again.

Parameters

extraInfo:Object: Extra information to be passed to the observer's callback method.

setChanged	back to summary
protected synchronized void setChanged() When the object state changes, the object calls this method in order to flag that fact. After this method has been called, then the notifyObservers() will wake up the observers which are watching this object.