eu.webtoolkit.jwt
Class Signal1<A1>

java.lang.Object
  extended by eu.webtoolkit.jwt.AbstractSignal
      extended by eu.webtoolkit.jwt.Signal1<A1>

public class Signal1<A1>
extends AbstractSignal

A signal that propagates events to listeners, and is capable of passing 1 argument.

A signal implements the Observer pattern, allowing one or more listeners to listen for events generated on the signal. The event may propagate an argument to the listeners.

For a usage example take a look the documentation of Signal2.


Nested Class Summary
static interface Signal1.Listener<A1>
          The listener interface.
 
Nested classes/interfaces inherited from class eu.webtoolkit.jwt.AbstractSignal
AbstractSignal.Connection
 
Constructor Summary
Signal1()
          Creates a new signal.
Signal1(WObject sender)
           
 
Method Summary
 AbstractSignal.Connection addListener(WObject listenerOwner, Signal.Listener listener)
          Adds a listener for this signal.
 AbstractSignal.Connection addListener(WObject listenerOwner, Signal1.Listener<A1> listener)
          Adds a listener for this signal.
 void removeListener(Signal.Listener listener)
          Removes a listener.
 void removeListener(Signal1.Listener<A1> listener)
          Removes a listener.
 void trigger(A1 arg)
          Triggers the signal.
 
Methods inherited from class eu.webtoolkit.jwt.AbstractSignal
getListenerCount, getListeners, isBlocked, isConnected, setBlocked
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Signal1

public Signal1()
Creates a new signal.


Signal1

public Signal1(WObject sender)
Method Detail

addListener

public AbstractSignal.Connection addListener(WObject listenerOwner,
                                             Signal1.Listener<A1> listener)
Adds a listener for this signal.

Each listener will be triggered whenever the signal is triggered.

Parameters:
listenerOwner - the enclosing object for a listener implemented using an (anonymous) inner class
listener - the listener
Returns:
a connection object that may be used to control the connection
See Also:
AbstractSignal.addListener(WObject, eu.webtoolkit.jwt.Signal.Listener)

removeListener

public void removeListener(Signal1.Listener<A1> listener)
Removes a listener.

Parameters:
listener - a listener that was previously added

trigger

public void trigger(A1 arg)
Triggers the signal.

The argument is passed to the listeners.

Parameters:
arg - The argument.

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

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.