| java.lang.Object
 EDU.oswego.cs.dl.util.concurrent.VetoableChangeMulticaster
| VetoableChangeMulticaster | | public class VetoableChangeMulticaster implements Serializable(Code) | | This class is interoperable with java.beans.VetoableChangeSupport,
but relies on a streamlined copy-on-write scheme similar to
that used in CopyOnWriteArrayList. It also adheres to clarified
semantics of add, remove, and fireVetoableChange operations.
Sample usage.
class Thing {
protected Color myColor = Color.red; // an example property
protected boolean changePending; // track whether in midst of change
// vetoable listeners:
protected VetoableChangeMulticaster vetoers =
new VetoableChangeMulticaster(this);
// Possibly also some ordinary listeners:
protected PropertyChangeMulticaster listeners =
new PropertyChangeMulticaster(this);
// registration methods, including:
void addVetoer(VetoableChangeListener l) {
// Use the `ifAbsent' version to avoid duplicate notifications
vetoers.addVetoableChangeListenerIfAbsent(l);
}
public synchronized Color getColor() { // accessor
return myColor;
}
// Simple transactional control for vetos
public void setColor(int newColor) throws PropertyVetoException {
Color oldColor = prepareSetColor(newColor);
try {
vetoers.fireVetoableChange("color", oldColor, newColor);
commitColor(newColor);
listeners.firePropertyChange("color", oldColor, newColor);
}
catch(PropertyVetoException ex) {
abortSetColor();
throw ex;
}
}
// Called on entry to proposed vetoable change from setColor.
// Throws exception if there is already another change in progress.
// Returns current color
synchronized int prepareSetColor(Color c) throws PropertyVetoException {
// only support one transaction at a time
if (changePending)
throw new PropertyVetoException("Concurrent modification");
// (Could alternatively wait out other transactions via
// a wait/notify construction based on changePending.)
// perhaps some other screenings, like:
else if (c == null)
throw new PropertyVetoException("Cannot change color to Null");
else {
changePending = true;
return myColor;
}
}
synchronized void commitColor(Color newColor) {
myColor = newColor;
changePending = false;
}
synchronized void abortSetColor() {
changePending = false;
}
}
[ Introduction to this package. ]
|
| Method Summary | |
| public synchronized void | addVetoableChangeListener(VetoableChangeListener listener)
Add a VetoableChangeListener to the listener list. | | public void | addVetoableChangeListener(String propertyName, VetoableChangeListener listener)
Add a VetoableChangeListener for a specific property. | | public synchronized void | addVetoableChangeListenerIfAbsent(VetoableChangeListener listener)
Add a PropertyChangeListener to the listener list if it is
not already present. | | public void | addVetoableChangeListenerIfAbsent(String propertyName, VetoableChangeListener listener)
Add a VetoableChangeListener for a specific property, if it is not
already registered. | | public void | fireVetoableChange(String propertyName, Object oldValue, Object newValue)
Report a vetoable property update to any registered listeners. | | public void | fireVetoableChange(String propertyName, int oldValue, int newValue)
Report a vetoable property update to any registered listeners. | | public void | fireVetoableChange(String propertyName, boolean oldValue, boolean newValue)
Report a vetoable property update to any registered listeners. | | public void | fireVetoableChange(PropertyChangeEvent evt)
Report a vetoable property update to any registered listeners. | | protected synchronized VetoableChangeMulticaster | getChild(String propertyName)
| | public boolean | hasListeners(String propertyName)
Check if there are any listeners for a specific property.
If propertyName is null, return whether there are any listeners at all.
Parameters:
propertyName - the property name. | | protected void | multicast(PropertyChangeEvent evt)
Helper method to relay evt to all listeners. | | public synchronized void | removeVetoableChangeListener(VetoableChangeListener listener)
Remove an occurrence of a VetoableChangeListener from the listener list. | | public void | removeVetoableChangeListener(String propertyName, VetoableChangeListener listener)
Remove a VetoableChangeListener for a specific property.
Affects only the given property. |
| children | | protected HashMap children(Code) | | HashMap for managing listeners for specific properties.
Maps property names to VetoableChangeMulticaster objects.
|
| source | | final protected Object source(Code) | | The object to be provided as the "source" for any generated events.
|
| VetoableChangeMulticaster | | public VetoableChangeMulticaster(Object sourceBean)(Code) | | Constructs a VetoableChangeMulticaster object.
Parameters:
sourceBean - The bean to be given as the source for any events.
exception:
NullPointerException - if sourceBean is null |
| addVetoableChangeListener | | public synchronized void addVetoableChangeListener(VetoableChangeListener listener)(Code) | | Add a VetoableChangeListener to the listener list.
The listener is registered for all properties.
If the listener is added multiple times, it will
receive multiple change notifications upon any fireVetoableChange.
Parameters:
listener - The VetoableChangeListener to be added |
| addVetoableChangeListener | | public void addVetoableChangeListener(String propertyName, VetoableChangeListener listener)(Code) | | Add a VetoableChangeListener for a specific property. The listener
will be invoked only when a call on fireVetoableChange names that
specific property. However, if a listener is registered both for all
properties and a specific property, it will receive multiple
notifications upon changes to that property.
Parameters:
propertyName - The name of the property to listen on.
Parameters:
listener - The VetoableChangeListener to be added
exception:
NullPointerException - If listener is null |
| addVetoableChangeListenerIfAbsent | | public synchronized void addVetoableChangeListenerIfAbsent(VetoableChangeListener listener)(Code) | | Add a PropertyChangeListener to the listener list if it is
not already present.
The listener is registered for all properties.
The operation maintains Set semantics: If the listener is already
registered, the operation has no effect.
Parameters:
listener - The PropertyChangeListener to be added
exception:
NullPointerException - If listener is null |
| addVetoableChangeListenerIfAbsent | | public void addVetoableChangeListenerIfAbsent(String propertyName, VetoableChangeListener listener)(Code) | | Add a VetoableChangeListener for a specific property, if it is not
already registered. The listener
will be invoked only when a call on fireVetoableChange names that
specific property.
Parameters:
propertyName - The name of the property to listen on.
Parameters:
listener - The VetoableChangeListener to be added
exception:
NullPointerException - If listener is null |
| fireVetoableChange | | public void fireVetoableChange(String propertyName, Object oldValue, Object newValue) throws PropertyVetoException(Code) | | Report a vetoable property update to any registered listeners.
Notifications are sent serially (although in no particular order)
to the list of listeners,
aborting if one throws PropertyVetoException. Upon this exception,
fire a new event reverting this
change to all listeners that have already been notified
(ignoring any further vetos),
suppress notifications to all other listeners, and
then rethrow the PropertyVetoException.
No event is fired if old and new are equal non-null.
Parameters:
propertyName - The programmatic name of the propertythat was changed.
Parameters:
oldValue - The old value of the property.
Parameters:
newValue - The new value of the property.
exception:
PropertyVetoException - if a recipient wishes the propertychange to be rolled back. |
| fireVetoableChange | | public void fireVetoableChange(String propertyName, int oldValue, int newValue) throws PropertyVetoException(Code) | | Report a vetoable property update to any registered listeners.
Notifications are sent serially (although in no particular order)
to the list of listeners,
aborting if one throws PropertyVetoException. Upon this exception,
fire a new event reverting this
change to all listeners that have already been notified
(ignoring any further vetos),
suppress notifications to all other listeners, and
then rethrow the PropertyVetoException.
No event is fired if old and new are equal.
This is merely a convenience wrapper around the more general
fireVetoableChange method that takes Object values.
Parameters:
propertyName - The programmatic name of the propertythat was changed.
Parameters:
oldValue - The old value of the property.
Parameters:
newValue - The new value of the property.
exception:
PropertyVetoException - if the recipient wishes the propertychange to be rolled back. |
| fireVetoableChange | | public void fireVetoableChange(String propertyName, boolean oldValue, boolean newValue) throws PropertyVetoException(Code) | | Report a vetoable property update to any registered listeners.
Notifications are sent serially (although in no particular order)
to the list of listeners,
aborting if one throws PropertyVetoException. Upon this exception,
fire a new event reverting this
change to all listeners that have already been notified
(ignoring any further vetos),
suppress notifications to all other listeners, and
then rethrow the PropertyVetoException.
No event is fired if old and new are equal.
This is merely a convenience wrapper around the more general
fireVetoableChange method that takes Object values.
Parameters:
propertyName - The programmatic name of the propertythat was changed.
Parameters:
oldValue - The old value of the property.
Parameters:
newValue - The new value of the property.
exception:
PropertyVetoException - if the recipient wishes the propertychange to be rolled back. |
| fireVetoableChange | | public void fireVetoableChange(PropertyChangeEvent evt) throws PropertyVetoException(Code) | | Report a vetoable property update to any registered listeners.
Notifications are sent serially (although in no particular order)
to the list of listeners,
aborting if one throws PropertyVetoException. Upon this exception,
fire a new event reverting this
change to all listeners that have already been notified
(ignoring any further vetos),
suppress notifications to all other listeners, and
then rethrow the PropertyVetoException.
No event is fired if old and new are equal and non-null.
equal and non-null.
Parameters:
evt - The PropertyChangeEvent object.
exception:
PropertyVetoException - if the recipient wishes the propertychange to be rolled back. |
| hasListeners | | public boolean hasListeners(String propertyName)(Code) | | Check if there are any listeners for a specific property.
If propertyName is null, return whether there are any listeners at all.
Parameters:
propertyName - the property name. true if there are one or more listeners for the given property |
| removeVetoableChangeListener | | public synchronized void removeVetoableChangeListener(VetoableChangeListener listener)(Code) | | Remove an occurrence of a VetoableChangeListener from the listener list.
It removes at most one occurrence of the given listener.
If the listener was added multiple times it must be removed
mulitple times.
This removes a VetoableChangeListener that was registered
for all properties, and has no effect if registered for only
one or more specified properties.
Parameters:
listener - The VetoableChangeListener to be removed |
| removeVetoableChangeListener | | public void removeVetoableChangeListener(String propertyName, VetoableChangeListener listener)(Code) | | Remove a VetoableChangeListener for a specific property.
Affects only the given property.
If the listener is also registered for all properties,
then it will continue to be registered for them.
Parameters:
propertyName - The name of the property that was listened on.
Parameters:
listener - The VetoableChangeListener to be removed |
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