eu.webtoolkit.jwt
Class JSignal

java.lang.Object
  eu.webtoolkit.jwt.AbstractSignal
      eu.webtoolkit.jwt.AbstractEventSignal
          eu.webtoolkit.jwt.AbstractJSignal
              eu.webtoolkit.jwt.JSignal

public class JSignal
extends AbstractJSignal

A signal that may be triggered from the browser with a JavaScript call. For a usage example take a look the documentation of JSignal2.

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

Constructor Summary

JSignal(WObject sender, java.lang.String name)
Creates a signal.

Method Summary

AbstractSignal.Connection	addListener(WObject receiver, Signal.Listener listener) Adds a listener for this signal.
java.lang.String	createCall() Returns a JavaScript statement that triggers 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.AbstractJSignal

createUserEventCall, getName

Methods inherited from class eu.webtoolkit.jwt.AbstractEventSignal

addListener, addListener, 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

Constructor Detail

JSignal

public JSignal(WObject sender,
               java.lang.String name)

Creates a signal.

Parameters:

sender - the object that will be identified as the sender for this signal.

name - the signal name (must be unique for each sender)

Method Detail

addListener

public AbstractSignal.Connection addListener(WObject receiver,
                                             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:

receiver - 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()

Triggers the signal.

Overrides:

trigger in class AbstractEventSignal

createCall

public java.lang.String createCall()

Returns a JavaScript statement that triggers this signal.

You can use this to trigger the signal from within generated JavaScript code.