ice.util.alg
Class Listeners

java.lang.Object
  ice.util.alg.Listeners

public class Listeners

extends Object

Set of utilities to support adding/removing of listeners in memory efficient way. Possible usage:

        private volatile Object _myListeners;

        public void addMyListener(TextListener l) {
                synchronized (this) {
                        _myListeners = Listeners.add(_myListeners, l);
                }
        }

        public void removeTextListener(TextListener l) {
                synchronized (this) {
                        _myListeners = Listeners.remove(_myListeners, l);
                }
        }

        public void fireMyEvent() {
        // Get immune local copy
                Object listeners = _myListeners;
                if (listeners != null) {
                        MyEvent e = new MyEvent(this);
                        for (int i = 0; ; ++i) {
                                MyListener l = (MyListener)Listeners.get(listeners, i);
                                if (l == null) { break; }
                                l.onMyEvent(e);
                        }
                }
        }

















Constructor Summary
Listeners()



           
 



Method Summary




static Object
add(Object listenerSet,
    Object listener)



          Add listener to listenerSet listener collection and
 return the resulting collection.



static Object
get(Object listenerSet,
    int index)



          Get listener at index in listenerSet or null if
 index equals to listenerSet length.



static Object
remove(Object listenerSet,
       Object listener)



          Removelistener from listenerSet listener collection and
 return the resulting collection.


 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 








Constructor Detail



Listeners
public Listeners()






Method Detail



add
public static Object add(Object listenerSet,
                         Object listener)

Add listener to listenerSet listener collection and
 return the resulting collection. The function does not modify
 listenerSet and if listener is presents there, it simply
 returns listenerSet.


Parameters:
listener - Listener to add to listenerSet
listenerSet - Current collection of listeners. Empty collection
                     always represented as the null value
Returns:
A listener collection that contains listener and all
         listeners from listenerSet
See Also:
remove(Object listenerSet, Object listener), 
get(Object listenerSet, int index)





remove
public static Object remove(Object listenerSet,
                            Object listener)

Removelistener from listenerSet listener collection and
 return the resulting collection. The function does not modify
 listenerSet and if listener is not presents there, it simply
 returns listenerSet.



Parameters:
listener - Listener to remove from listenerSet
listenerSet - Current collection of listeners.
Returns:
A listener collection with listener removed.
See Also:
add(Object listenerSet, Object listener), 
get(Object listenerSet, int index)





get
public static Object get(Object listenerSet,
                         int index)

Get listener at index in listenerSet or null if
 index equals to listenerSet length.


Parameters:
listenerSet - Collection of listeners.
Throws:
RuntimeException - if listenerSet is null
RuntimeException - if index ≥ length of listenerSet
See Also:
add(Object listenerSet, Object listener), 
remove(Object listenerSet, Object listener)