Package org.apache.commons.lang3.event
Class EventListenerSupport<L>
- java.lang.Object
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- org.apache.commons.lang3.event.EventListenerSupport<L>
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- Type Parameters:
L
- the type of event listener that is supported by this proxy.
- All Implemented Interfaces:
java.io.Serializable
public class EventListenerSupport<L> extends java.lang.Object implements java.io.Serializable
An EventListenerSupport object can be used to manage a list of event listeners of a particular type. The class provides
addListener(Object)
andremoveListener(Object)
methods for registering listeners, as well as afire()
method for firing events to the listeners.To use this class, suppose you want to support ActionEvents. You would do:
public class MyActionEventSource { private EventListenerSupport<ActionListener> actionListeners = EventListenerSupport.create(ActionListener.class); public void someMethodThatFiresAction() { ActionEvent e = new ActionEvent(this, ActionEvent.ACTION_PERFORMED, "somethingCool"); actionListeners.fire().actionPerformed(e); } }
Serializing an
EventListenerSupport
instance will result in any non-Serializable
listeners being silently dropped.- Since:
- 3.0
- See Also:
- Serialized Form
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Constructor Summary
Constructors Constructor Description EventListenerSupport(java.lang.Class<L> listenerInterface)
Creates an EventListenerSupport object which supports the provided listener interface.EventListenerSupport(java.lang.Class<L> listenerInterface, java.lang.ClassLoader classLoader)
Creates an EventListenerSupport object which supports the provided listener interface using the specified class loader to create the JDK dynamic proxy.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description void
addListener(L listener)
Registers an event listener.void
addListener(L listener, boolean allowDuplicate)
Registers an event listener.static <T> EventListenerSupport<T>
create(java.lang.Class<T> listenerInterface)
Creates an EventListenerSupport object which supports the specified listener type.L
fire()
Returns a proxy object which can be used to call listener methods on all of the registered event listeners.L[]
getListeners()
Gets an array containing the currently registered listeners.void
removeListener(L listener)
Unregisters an event listener.
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Constructor Detail
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EventListenerSupport
public EventListenerSupport(java.lang.Class<L> listenerInterface)
Creates an EventListenerSupport object which supports the provided listener interface.- Parameters:
listenerInterface
- the type of listener interface that will receive events posted using this class.- Throws:
java.lang.NullPointerException
- iflistenerInterface
isnull
.java.lang.IllegalArgumentException
- iflistenerInterface
is not an interface.
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EventListenerSupport
public EventListenerSupport(java.lang.Class<L> listenerInterface, java.lang.ClassLoader classLoader)
Creates an EventListenerSupport object which supports the provided listener interface using the specified class loader to create the JDK dynamic proxy.- Parameters:
listenerInterface
- the listener interface.classLoader
- the class loader.- Throws:
java.lang.NullPointerException
- iflistenerInterface
orclassLoader
isnull
.java.lang.IllegalArgumentException
- iflistenerInterface
is not an interface.
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Method Detail
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create
public static <T> EventListenerSupport<T> create(java.lang.Class<T> listenerInterface)
Creates an EventListenerSupport object which supports the specified listener type.- Type Parameters:
T
- the type of the listener interface- Parameters:
listenerInterface
- the type of listener interface that will receive events posted using this class.- Returns:
- an EventListenerSupport object which supports the specified listener type.
- Throws:
java.lang.NullPointerException
- iflistenerInterface
isnull
.java.lang.IllegalArgumentException
- iflistenerInterface
is not an interface.
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fire
public L fire()
Returns a proxy object which can be used to call listener methods on all of the registered event listeners. All calls made to this proxy will be forwarded to all registered listeners.- Returns:
- a proxy object which can be used to call listener methods on all of the registered event listeners
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addListener
public void addListener(L listener)
Registers an event listener.- Parameters:
listener
- the event listener (may not benull
).- Throws:
java.lang.NullPointerException
- iflistener
isnull
.
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addListener
public void addListener(L listener, boolean allowDuplicate)
Registers an event listener. Will not add a pre-existing listener object to the list ifallowDuplicate
is false.- Parameters:
listener
- the event listener (may not benull
).allowDuplicate
- the flag for determining if duplicate listener objects are allowed to be registered.- Throws:
java.lang.NullPointerException
- iflistener
isnull
.- Since:
- 3.5
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removeListener
public void removeListener(L listener)
Unregisters an event listener.- Parameters:
listener
- the event listener (may not benull
).- Throws:
java.lang.NullPointerException
- iflistener
isnull
.
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getListeners
public L[] getListeners()
Gets an array containing the currently registered listeners. Modification to this array's elements will have no effect on theEventListenerSupport
instance.- Returns:
- L[]
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