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com.virtuosotechnologies.lib.util
Class EventBroadcastHelper  

java.lang.Object
  com.virtuosotechnologies.lib.util.EventBroadcastHelper

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public final class EventBroadcastHelper

extends java.lang.Object

A helper class for broadcasting events.

This class is meant to be used internally by any class that needs to broadcast events. It provides the following facilities:

• It manages a set of listeners, providing helper methods for adding and removing listeners.
• It optionally references listeners via weak references, so they can be garbage collected and do not need to be removed explicitly.
• It provides methods for broadcasting an event to all listeners.

Typical usage will involve keeping a data member of type EventBroadcastHelper in your client class. Your add*Listener() and remove*Listener() methods can delegate to this helper, and you may use the helper's fireEvent() method to fire events.

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Field Summary
private  java.lang.Class	listenerClass_
private  java.util.List	listeners_
private  java.lang.String	name_
private  boolean	verbose_

 

Constructor Summary

EventBroadcastHelper(java.lang.Class listenerClass)           Constructor.

 

Method Summary
private  boolean	addListenerHelper(java.util.EventListener listener)           Helper for addListener methods.
void	addListenerStrong(java.util.EventListener listener)           Add a listener to the set of listeners.
void	addListenerWeak(java.util.EventListener listener)           Add a listener to the set of listeners.
void	fireAbortableEvent(java.lang.reflect.Method method, java.util.EventObject event)           Fires an event.
void	fireAbortableEvent(java.lang.String methodName, java.util.EventObject event)           Fires an event.
void	fireEvent(java.lang.reflect.Method method, java.util.EventObject event)           Fires an event.
void	fireEvent(java.lang.String methodName, java.util.EventObject event)           Fires an event.
java.lang.Class	getListenerClass()           Returns the listener class associated with this broadcaster.
static java.lang.reflect.Method	getListenerMethod(java.lang.Class listenerClass, java.lang.String name, java.lang.Class eventClass)           A helper for listener interfaces that want to provide static Method members for fast access to their methods.
java.util.List	getListenersAsList()           Returns a copy of the set of listeners as a list.
java.util.Set	getListenersAsSet()           Returns a copy of the set of listeners as a set.
static java.lang.reflect.Method	getUniqueListenerMethod(java.lang.Class listenerClass)           A helper for listener interfaces that want to provide static Method members for fast access to their methods.
boolean	isVerbose()           Get verbose mode
void	removeAllListeners()           Removes all listeners from the set of listeners.
void	removeListener(java.util.EventListener listener)           Removes a listener from the set of listeners.
void	setName(java.lang.String name)           Set identifying name that will be returned from toString
void	setVerbose(boolean verbose)           Set verbose mode
java.lang.String	toString()           toString override

 

Methods inherited from class java.lang.Object

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

 

Field Detail

listenerClass_

private java.lang.Class listenerClass_

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listeners_

private java.util.List listeners_

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verbose_

private boolean verbose_

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name_

private java.lang.String name_

Constructor Detail

EventBroadcastHelper

public EventBroadcastHelper(java.lang.Class listenerClass)

Constructor.

Method Detail

getListenerMethod

public static java.lang.reflect.Method getListenerMethod(java.lang.Class listenerClass,
                                                         java.lang.String name,
                                                         java.lang.Class eventClass)

A helper for listener interfaces that want to provide static Method members for fast access to their methods. This allows a listener interface to initialize a static member in a single line so a static initializer inner class is not needed.

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getUniqueListenerMethod

public static java.lang.reflect.Method getUniqueListenerMethod(java.lang.Class listenerClass)

A helper for listener interfaces that want to provide static Method members for fast access to their methods. This version assumes that the listener class declares exactly one method, and it returns that method.

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isVerbose

public boolean isVerbose()

Get verbose mode

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setVerbose

public void setVerbose(boolean verbose)

Set verbose mode

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setName

public void setName(java.lang.String name)

Set identifying name that will be returned from toString

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toString

public java.lang.String toString()

toString override

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getListenerClass

public java.lang.Class getListenerClass()

Returns the listener class associated with this broadcaster.

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addListenerHelper

private boolean addListenerHelper(java.util.EventListener listener)

Helper for addListener methods. Checks to make sure the listener is valid, and isn't already added. Returns true if it is okay to add the listener.

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addListenerWeak

public void addListenerWeak(java.util.EventListener listener)

Add a listener to the set of listeners. Has no effect if the listener is already in the set. References the new listener through a weak reference, which means the reference will go away when the listener gets collected. This has two implications:

• If the listener is going to get collected otherwise, you don't need to explicitly remove it from the listener list.
• You shouldn't add a listener weakly without storing a reference to it, or it might get collected prematurely. For example, the following is a no-no:

  addListenerWeak(new MyListener());

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addListenerStrong

public void addListenerStrong(java.util.EventListener listener)

Add a listener to the set of listeners. Has no effect if the listener is already in the set. References the new listener through a strong reference, which means the reference will not be collected until the listener is explicitly removed.

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removeListener

public void removeListener(java.util.EventListener listener)

Removes a listener from the set of listeners. Has no effect if the listener is not in the list.

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removeAllListeners

public void removeAllListeners()

Removes all listeners from the set of listeners.

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getListenersAsSet

public java.util.Set getListenersAsSet()

Returns a copy of the set of listeners as a set. The copy is not backed by the original, so modifications made to the returned set do not affect the actual set of listeners.

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getListenersAsList

public java.util.List getListenersAsList()

Returns a copy of the set of listeners as a list. The copy is not backed by the original, so modifications made to the returned list do not affect the actual set of listeners.

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fireEvent

public void fireEvent(java.lang.String methodName,
                      java.util.EventObject event)

Fires an event. This version takes the name of the method to invoke and an event object to send.

This version of fireEvent may be a little slow because it looks up the method object from the name and parameters via reflection. If an event is to be fired rapidly, you may want to create and cache the method object yourself, and call the other version of fireEvent() that takes a method object.

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fireEvent

public void fireEvent(java.lang.reflect.Method method,
                      java.util.EventObject event)

Fires an event. This version takes a method object to invoke and an event object to send.

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fireAbortableEvent

public void fireAbortableEvent(java.lang.String methodName,
                               java.util.EventObject event)
                        throws EventAbortedException

Fires an event. This version takes the name of the method to invoke and an event object to send.

This version of fireEvent may be a little slow because it looks up the method object from the name and parameters via reflection. If an event is to be fired rapidly, you may want to create and cache the method object yourself, and call the other version of fireEvent() that takes a method object.

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fireAbortableEvent

public void fireAbortableEvent(java.lang.reflect.Method method,
                               java.util.EventObject event)
                        throws EventAbortedException

Fires an event. This version takes a method object to invoke and an event object to send.

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