eu.webtoolkit.jwt
Class EventSignal

java.lang.Object
  eu.webtoolkit.jwt.AbstractSignal
      eu.webtoolkit.jwt.AbstractEventSignal
          eu.webtoolkit.jwt.EventSignal

public class EventSignal
extends AbstractEventSignal

An signal which relays a browser event. This event signal does not pass any event details.

Nested Class Summary

Nested classes/interfaces inherited from class eu.webtoolkit.jwt.AbstractEventSignal

AbstractEventSignal.AutoLearnListener, AbstractEventSignal.JavaScriptListener, AbstractEventSignal.LearningListener, AbstractEventSignal.PreLearnListener

Nested classes/interfaces inherited from class eu.webtoolkit.jwt.AbstractSignal

AbstractSignal.Connection

Method Summary

void	addListener(JSlot slot) Adds a JavaScript event listener.
void	addListener(WObject receiver, AbstractEventSignal.LearningListener listener) Adds a learning listener to this signal.
AbstractSignal.Connection	addListener(WObject listenerOwner, Signal.Listener listener) Adds a listener for this signal.
protected int	getListenerCount() Returns the number of connected listeners.
void	removeListener(Signal.Listener listener) Removes a listener.
void	trigger() Triggers the signal.

Methods inherited from class eu.webtoolkit.jwt.AbstractEventSignal

addListener, addListener, addListener, addListener, createUserEventCall, disconnect, isConnected, isDefaultActionPrevented, isPropagationPrevented, preventDefaultAction, preventDefaultAction, preventPropagation, preventPropagation, removeListener

Methods inherited from class eu.webtoolkit.jwt.AbstractSignal

getListeners, isBlocked, setBlocked

Methods inherited from class java.lang.Object

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

Method Detail

addListener

public AbstractSignal.Connection addListener(WObject listenerOwner,
                                             Signal.Listener listener)

Description copied from class: AbstractSignal

Adds a listener for this signal.

Each listener will be notified when the signal is triggered.

An owner object may be passed when the listener is implemented using an (anonymous) inner class. In that case the owner object should be the enclosing object of the listener object, and this is used to bind the lifetime of the listener. To avoid the owner object from not being garbage collected when it is no longer used, only the owner object will add a reference to the listener, while the signal will use a weak reference.

This avoids the most common reason for memory leaks in Java implementations of the Observer pattern: the owner object will not get garbage collected because of the (anonymous) listener object having a reference to it, even if the receiver object is no longer referenced from anywhere. When the owner object is not null, the listener is stored using a strong reference in the owner object, and using a weak reference in the signal.

Specified by:

addListener in class AbstractSignal

Parameters:

listenerOwner - if not null, the enclosing object for a listener implemented using an inner class

listener - the listener

Returns:

a connection object that may be used to control the connection

getListenerCount

protected int getListenerCount()

Description copied from class: AbstractSignal

Returns the number of connected listeners.

Overrides:

getListenerCount in class AbstractEventSignal

Returns:

the number of connected listeners.

removeListener

public void removeListener(Signal.Listener listener)

Description copied from class: AbstractSignal

Removes a listener.

Specified by:

removeListener in class AbstractSignal

Parameters:

listener - a listener that was previously added.

trigger

public void trigger()

Description copied from class: AbstractEventSignal

Triggers the signal.

The AbstractEventSignal.LearningListener.trigger() method of all listeners added to this signal are triggered.

Overrides:

trigger in class AbstractEventSignal

addListener

public void addListener(JSlot slot)

Description copied from class: AbstractEventSignal

Adds a JavaScript event listener.

Overrides:

addListener in class AbstractEventSignal

Parameters:

slot - the JavaScript event listener

addListener

public void addListener(WObject receiver,
                        AbstractEventSignal.LearningListener listener)

Description copied from class: AbstractEventSignal

Adds a learning listener to this signal.

An owner object may be passed when the listener is implemented using an anonymous inner class. In that case the owner object should be the enclosing object of the listener object, and this is used to bind the lifetime of the listener: when the owner object is garbage collected, the listener will be freed as well. This avoids the most common reason for memory leaks in Java implementations of the Observer pattern: the owner object will not get garbage collected because of the (anonymous) listener object having a reference to it, even if the receiver object is no longer referenced from anywhere. When the owner object is not null, the listener is stored using a strong reference in the owner object, and using a weak reference in the signal. Note: The receiver is currently not yet used.

Overrides:

addListener in class AbstractEventSignal

Parameters:

receiver - if not null, the enclosing object for an anonymous listener

listener - the listener