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com.cosylab.util
Class ListenerList

java.lang.Object
  com.cosylab.util.ObjectList
      com.cosylab.util.ListenerList

All Implemented Interfaces:

java.io.Serializable, java.lang.Iterable, java.util.Collection, java.util.List

public class ListenerList
extends ObjectList

A listener list is an efficient data structure for holding listeners. Its design is based on the fact that listeners are extensively accessed for event dispatching, but the collection of listeners changes rarely. Under these circumstances (especilly rare invocations of addListener() and removeListener methods) this class is a good choice. It holds listeners in an array that is trimmed every time the listener membership changes (which is quite inefficient). On the other hand, accessing the elements of the array is quick, on the condition and contract that the client does not modify the array being returned. Also note that the array is of the correct run-time type specified by the constructor of this class, and can therefore be cast. For example, if you speficy WindowListener as the RTT of this list, you can perform WindowListener[] wla = (WindowListener[])toArray() without raising a ClassCastException. For cases where the listener membership changes often, but events are dispatched rarely, use ArrayList instead. This class is thread safe, there is no need for additional synchronization. See also swing based listener registration for an approach that is more time consuming during dispatching, but can store different classes of listeners in a single array.

Version:

$id$

Author:

Gasper Tkacik

See Also:

EventListenerList, Serialized Form

Constructor Summary

ListenerList(java.lang.Class type)
Constructs a new instance of the listener list that will be used to hold elements of type type.

Method Summary

Methods inherited from class com.cosylab.util.ObjectList

add, add, add, addAll, addAll, clear, contains, containsAll, get, indexOf, isEmpty, iterator, lastIndexOf, listIterator, listIterator, remove, remove, removeAll, retainAll, set, size, subList, toArray, toArray, toArray, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.util.List

equals, hashCode

Constructor Detail

ListenerList

public ListenerList(java.lang.Class type)

Constructs a new instance of the listener list that will be used to hold elements of type type. The specified class should be a subclass of java.util.EventListener.

Parameters:

type - a run-time type of the elements in this list

Throws:

java.lang.NullPointerException - DOCUMENT ME!

java.lang.IllegalArgumentException - DOCUMENT ME!