org.eclipse.core.runtime
Class ListenerList
java.lang.Object
org.eclipse.core.runtime.ListenerList
-
Direct Known Subclasses:
-
ListenerList
-
public class ListenerList
- extends
Object
This class is a thread safe list that is designed for storing lists of listeners.
The implementation is optimized for minimal memory footprint, frequent reads
and infrequent writes. Modification of the list is synchronized and relatively
expensive, while accessing the listeners is very fast. Readers are given access
to the underlying array data structure for reading, with the trust that they will
not modify the underlying array.
A listener list handles the same listener being added
multiple times, and tolerates removal of listeners that are the same as other
listeners in the list. For this purpose, listeners can be compared with each other
using either equality or identity, as specified in the list constructor.
Use the getListeners
method when notifying listeners. The recommended
code sequence for notifying all registered listeners of say,
FooListener.eventHappened
, is:
Object[] listeners = myListenerList.getListeners();
for (int i = 0; i < listeners.length; ++i) {
((FooListener) listeners[i]).eventHappened(event);
}
This class can be used without OSGi running.
-
Since:
- org.eclipse.equinox.common 3.2
Field Summary
|
static int
|
EQUALITY
Mode constant (value 0) indicating that listeners should be considered
the
same if they are equal. |
static int
|
IDENTITY
Mode constant (value 1) indicating that listeners should be considered
the
same if they are identical. |
Constructor Summary
|
ListenerList
()
Creates a listener list in which listeners are compared using equality. |
ListenerList
(int mode)
Creates a listener list using the provided comparison mode. |
Method Summary
|
void
|
add
(
Object listener)
Adds a listener to this list. |
void
|
clear
()
Removes all listeners from this list. |
Object[]
|
getListeners
()
Returns an array containing all the registered listeners. |
boolean
|
isEmpty
()
Returns whether this listener list is empty. |
void
|
remove
(
Object listener)
Removes a listener from this list. |
int
|
size
()
Returns the number of registered listeners. |
Methods inherited from class java.lang.
Object
|
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
|
EQUALITY
public static final int EQUALITY
- Mode constant (value 0) indicating that listeners should be considered
the
same if they are equal.
-
See Also:
-
Constant Field Values
IDENTITY
public static final int IDENTITY
- Mode constant (value 1) indicating that listeners should be considered
the
same if they are identical.
-
See Also:
-
Constant Field Values
ListenerList
public ListenerList()
- Creates a listener list in which listeners are compared using equality.
ListenerList
public ListenerList(int mode)
- Creates a listener list using the provided comparison mode.
-
Parameters:
-
mode
- The mode used to determine if listeners are the
same.
add
public void add(
Object listener)
- Adds a listener to this list. This method has no effect if the
same
listener is already registered.
-
-
Parameters:
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listener
- the non-null
listener to add
getListeners
public
Object[] getListeners()
- Returns an array containing all the registered listeners.
The resulting array is unaffected by subsequent adds or removes.
If there are no listeners registered, the result is an empty array.
Use this method when notifying listeners, so that any modifications
to the listener list during the notification will have no effect on
the notification itself.
Note: Callers of this method must not modify the returned array.
-
-
Returns:
- the list of registered listeners
isEmpty
public boolean isEmpty()
- Returns whether this listener list is empty.
-
-
Returns:
-
true
if there are no registered listeners, and
false
otherwise
remove
public void remove(
Object listener)
- Removes a listener from this list. Has no effect if the
same
listener was not already registered.
-
-
Parameters:
-
listener
- the non-null
listener to remove
size
public int size()
- Returns the number of registered listeners.
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-
Returns:
- the number of registered listeners
clear
public void clear()
- Removes all listeners from this list.
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Guidelines for using Eclipse APIs.
Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.