PropertyChangeSupport
public
class
PropertyChangeSupport
extends Object
implements
Serializable
java.lang.Object | |
↳ | java.beans.PropertyChangeSupport |
This is a utility class that can be used by beans that support bound
properties. It manages a list of listeners and dispatches
PropertyChangeEvent
s to them. You can use an instance of this class
as a member field of your bean and delegate these types of work to it.
The PropertyChangeListener
can be registered for all properties
or for a property specified by name.
Here is an example of PropertyChangeSupport
usage that follows
the rules and recommendations laid out in the JavaBeans™ specification:
public class MyBean { private final PropertyChangeSupport pcs = new PropertyChangeSupport(this); public void addPropertyChangeListener(PropertyChangeListener listener) { this.pcs.addPropertyChangeListener(listener); } public void removePropertyChangeListener(PropertyChangeListener listener) { this.pcs.removePropertyChangeListener(listener); } private String value; public String getValue() { return this.value; } public void setValue(String newValue) { String oldValue = this.value; this.value = newValue; this.pcs.firePropertyChange("value", oldValue, newValue); } [...] }
A PropertyChangeSupport
instance is thread-safe.
This class is serializable. When it is serialized it will save (and restore) any listeners that are themselves serializable. Any non-serializable listeners will be skipped during serialization.
Summary
Public constructors | |
---|---|
PropertyChangeSupport(Object sourceBean)
Constructs a |
Public methods | |
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void
|
addPropertyChangeListener(PropertyChangeListener listener)
Add a PropertyChangeListener to the listener list. |
void
|
addPropertyChangeListener(String propertyName, PropertyChangeListener listener)
Add a PropertyChangeListener for a specific property. |
void
|
fireIndexedPropertyChange(String propertyName, int index, boolean oldValue, boolean newValue)
Reports a boolean bound indexed property update to listeners that have been registered to track updates of all properties or a property with the specified name. |
void
|
fireIndexedPropertyChange(String propertyName, int index, int oldValue, int newValue)
Reports an integer bound indexed property update to listeners that have been registered to track updates of all properties or a property with the specified name. |
void
|
fireIndexedPropertyChange(String propertyName, int index, Object oldValue, Object newValue)
Reports a bound indexed property update to listeners that have been registered to track updates of all properties or a property with the specified name. |
void
|
firePropertyChange(String propertyName, Object oldValue, Object newValue)
Reports a bound property update to listeners that have been registered to track updates of all properties or a property with the specified name. |
void
|
firePropertyChange(PropertyChangeEvent event)
Fires a property change event to listeners that have been registered to track updates of all properties or a property with the specified name. |
void
|
firePropertyChange(String propertyName, boolean oldValue, boolean newValue)
Reports a boolean bound property update to listeners that have been registered to track updates of all properties or a property with the specified name. |
void
|
firePropertyChange(String propertyName, int oldValue, int newValue)
Reports an integer bound property update to listeners that have been registered to track updates of all properties or a property with the specified name. |
PropertyChangeListener[]
|
getPropertyChangeListeners(String propertyName)
Returns an array of all the listeners which have been associated with the named property. |
PropertyChangeListener[]
|
getPropertyChangeListeners()
Returns an array of all the listeners that were added to the PropertyChangeSupport object with addPropertyChangeListener(). |
boolean
|
hasListeners(String propertyName)
Check if there are any listeners for a specific property, including those registered on all properties. |
void
|
removePropertyChangeListener(String propertyName, PropertyChangeListener listener)
Remove a PropertyChangeListener for a specific property. |
void
|
removePropertyChangeListener(PropertyChangeListener listener)
Remove a PropertyChangeListener from the listener list. |
Inherited methods | |
---|---|
Public constructors
PropertyChangeSupport
public PropertyChangeSupport (Object sourceBean)
Constructs a PropertyChangeSupport
object.
Parameters | |
---|---|
sourceBean |
Object : The bean to be given as the source for any events. |
Public methods
addPropertyChangeListener
public void addPropertyChangeListener (PropertyChangeListener listener)
Add a PropertyChangeListener to the listener list.
The listener is registered for all properties.
The same listener object may be added more than once, and will be called
as many times as it is added.
If listener
is null, no exception is thrown and no action
is taken.
Parameters | |
---|---|
listener |
PropertyChangeListener : The PropertyChangeListener to be added |
addPropertyChangeListener
public void addPropertyChangeListener (String propertyName, PropertyChangeListener listener)
Add a PropertyChangeListener for a specific property. The listener
will be invoked only when a call on firePropertyChange names that
specific property.
The same listener object may be added more than once. For each
property, the listener will be invoked the number of times it was added
for that property.
If propertyName
or listener
is null, no
exception is thrown and no action is taken.
Parameters | |
---|---|
propertyName |
String : The name of the property to listen on. |
listener |
PropertyChangeListener : The PropertyChangeListener to be added |
fireIndexedPropertyChange
public void fireIndexedPropertyChange (String propertyName, int index, boolean oldValue, boolean newValue)
Reports a boolean bound indexed property update to listeners that have been registered to track updates of all properties or a property with the specified name.
No event is fired if old and new values are equal.
This is merely a convenience wrapper around the more general
fireIndexedPropertyChange(java.lang.String, int, java.lang.Object, java.lang.Object)
method.
Parameters | |
---|---|
propertyName |
String : the programmatic name of the property that was changed |
index |
int : the index of the property element that was changed |
oldValue |
boolean : the old value of the property |
newValue |
boolean : the new value of the property |
fireIndexedPropertyChange
public void fireIndexedPropertyChange (String propertyName, int index, int oldValue, int newValue)
Reports an integer bound indexed property update to listeners that have been registered to track updates of all properties or a property with the specified name.
No event is fired if old and new values are equal.
This is merely a convenience wrapper around the more general
fireIndexedPropertyChange(java.lang.String, int, java.lang.Object, java.lang.Object)
method.
Parameters | |
---|---|
propertyName |
String : the programmatic name of the property that was changed |
index |
int : the index of the property element that was changed |
oldValue |
int : the old value of the property |
newValue |
int : the new value of the property |
fireIndexedPropertyChange
public void fireIndexedPropertyChange (String propertyName, int index, Object oldValue, Object newValue)
Reports a bound indexed property update to listeners that have been registered to track updates of all properties or a property with the specified name.
No event is fired if old and new values are equal and non-null.
This is merely a convenience wrapper around the more general
firePropertyChange(java.beans.PropertyChangeEvent)
method.
Parameters | |
---|---|
propertyName |
String : the programmatic name of the property that was changed |
index |
int : the index of the property element that was changed |
oldValue |
Object : the old value of the property |
newValue |
Object : the new value of the property |
firePropertyChange
public void firePropertyChange (String propertyName, Object oldValue, Object newValue)
Reports a bound property update to listeners that have been registered to track updates of all properties or a property with the specified name.
No event is fired if old and new values are equal and non-null.
This is merely a convenience wrapper around the more general
firePropertyChange(java.beans.PropertyChangeEvent)
method.
Parameters | |
---|---|
propertyName |
String : the programmatic name of the property that was changed |
oldValue |
Object : the old value of the property |
newValue |
Object : the new value of the property |
firePropertyChange
public void firePropertyChange (PropertyChangeEvent event)
Fires a property change event to listeners that have been registered to track updates of all properties or a property with the specified name.
No event is fired if the given event's old and new values are equal and non-null.
Parameters | |
---|---|
event |
PropertyChangeEvent : the PropertyChangeEvent to be fired |
firePropertyChange
public void firePropertyChange (String propertyName, boolean oldValue, boolean newValue)
Reports a boolean bound property update to listeners that have been registered to track updates of all properties or a property with the specified name.
No event is fired if old and new values are equal.
This is merely a convenience wrapper around the more general
firePropertyChange(java.lang.String, java.lang.Object, java.lang.Object)
method.
Parameters | |
---|---|
propertyName |
String : the programmatic name of the property that was changed |
oldValue |
boolean : the old value of the property |
newValue |
boolean : the new value of the property |
firePropertyChange
public void firePropertyChange (String propertyName, int oldValue, int newValue)
Reports an integer bound property update to listeners that have been registered to track updates of all properties or a property with the specified name.
No event is fired if old and new values are equal.
This is merely a convenience wrapper around the more general
firePropertyChange(java.lang.String, java.lang.Object, java.lang.Object)
method.
Parameters | |
---|---|
propertyName |
String : the programmatic name of the property that was changed |
oldValue |
int : the old value of the property |
newValue |
int : the new value of the property |
getPropertyChangeListeners
public PropertyChangeListener[] getPropertyChangeListeners (String propertyName)
Returns an array of all the listeners which have been associated with the named property.
Parameters | |
---|---|
propertyName |
String : The name of the property being listened to |
Returns | |
---|---|
PropertyChangeListener[] |
all of the PropertyChangeListeners associated with
the named property. If no such listeners have been added,
or if propertyName is null, an empty array is
returned. |
getPropertyChangeListeners
public PropertyChangeListener[] getPropertyChangeListeners ()
Returns an array of all the listeners that were added to the PropertyChangeSupport object with addPropertyChangeListener().
If some listeners have been added with a named property, then
the returned array will be a mixture of PropertyChangeListeners
and PropertyChangeListenerProxy
s. If the calling
method is interested in distinguishing the listeners then it must
test each element to see if it's a
PropertyChangeListenerProxy
, perform the cast, and examine
the parameter.
PropertyChangeListener[] listeners = bean.getPropertyChangeListeners();
for (int i = 0; i < listeners.length; i++) {
if (listeners[i] instanceof PropertyChangeListenerProxy) {
PropertyChangeListenerProxy proxy =
(PropertyChangeListenerProxy)listeners[i];
if (proxy.getPropertyName().equals("foo")) {
// proxy is a PropertyChangeListener which was associated
// with the property named "foo"
}
}
}
Returns | |
---|---|
PropertyChangeListener[] |
all of the PropertyChangeListeners added or an
empty array if no listeners have been added |
See also:
hasListeners
public boolean hasListeners (String propertyName)
Check if there are any listeners for a specific property, including
those registered on all properties. If propertyName
is null, only check for listeners registered on all properties.
Parameters | |
---|---|
propertyName |
String : the property name. |
Returns | |
---|---|
boolean |
true if there are one or more listeners for the given property |
removePropertyChangeListener
public void removePropertyChangeListener (String propertyName, PropertyChangeListener listener)
Remove a PropertyChangeListener for a specific property.
If listener
was added more than once to the same event
source for the specified property, it will be notified one less time
after being removed.
If propertyName
is null, no exception is thrown and no
action is taken.
If listener
is null, or was never added for the specified
property, no exception is thrown and no action is taken.
Parameters | |
---|---|
propertyName |
String : The name of the property that was listened on. |
listener |
PropertyChangeListener : The PropertyChangeListener to be removed |
removePropertyChangeListener
public void removePropertyChangeListener (PropertyChangeListener listener)
Remove a PropertyChangeListener from the listener list.
This removes a PropertyChangeListener that was registered
for all properties.
If listener
was added more than once to the same event
source, it will be notified one less time after being removed.
If listener
is null, or was never added, no exception is
thrown and no action is taken.
Parameters | |
---|---|
listener |
PropertyChangeListener : The PropertyChangeListener to be removed |