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Diffstat (limited to 'libjava/java/beans/PropertyChangeListenerProxy.java')
-rw-r--r-- | libjava/java/beans/PropertyChangeListenerProxy.java | 102 |
1 files changed, 102 insertions, 0 deletions
diff --git a/libjava/java/beans/PropertyChangeListenerProxy.java b/libjava/java/beans/PropertyChangeListenerProxy.java new file mode 100644 index 00000000000..6e707038d06 --- /dev/null +++ b/libjava/java/beans/PropertyChangeListenerProxy.java @@ -0,0 +1,102 @@ +/* PropertyChangeListenerProxy.java -- adds a name to a property listener + Copyright (C) 2002 Free Software Foundation, Inc. + +This file is part of GNU Classpath. + +GNU Classpath is free software; you can redistribute it and/or modify +it under the terms of the GNU General Public License as published by +the Free Software Foundation; either version 2, or (at your option) +any later version. + +GNU Classpath is distributed in the hope that it will be useful, but +WITHOUT ANY WARRANTY; without even the implied warranty of +MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +General Public License for more details. + +You should have received a copy of the GNU General Public License +along with GNU Classpath; see the file COPYING. If not, write to the +Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA +02111-1307 USA. + +Linking this library statically or dynamically with other modules is +making a combined work based on this library. Thus, the terms and +conditions of the GNU General Public License cover the whole +combination. + +As a special exception, the copyright holders of this library give you +permission to link this library with independent modules to produce an +executable, regardless of the license terms of these independent +modules, and to copy and distribute the resulting executable under +terms of your choice, provided that you also meet, for each linked +independent module, the terms and conditions of the license of that +module. An independent module is a module which is not derived from +or based on this library. If you modify this library, you may extend +this exception to your version of the library, but you are not +obligated to do so. If you do not wish to do so, delete this +exception statement from your version. */ + + +package java.beans; + +import java.util.EventListenerProxy; + +/** + * This class provides an extension to <code>PropertyChangeListener</code> - + * associating a name with the listener. This can be used to filter the + * changes that one is interested in. + * + * @author Eric Blake <ebb9@email.byu.edu> + * @since 1.4 + * @status udpated to 1.4 + */ +public class PropertyChangeListenerProxy extends EventListenerProxy + implements PropertyChangeListener +{ + /** + * The name of the property to listen for. Package visible for use by + * PropertyChangeSupport. + */ + final String propertyName; + + /** + * Create a new proxy which filters property change events and only passes + * changes to the named property on to the delegate. A null propertyName + * or listener does not fail now, but may cause a NullPointerException down + * the road. + * + * @param propertyName the property's name to filter on + * @param listener the delegate listener + */ + public PropertyChangeListenerProxy(String propertyName, + PropertyChangeListener listener) + { + super(listener); + this.propertyName = propertyName; + } + + /** + * Forwards the event on to the delegate if the property name matches. + * + * @param event the event to pass on, if it meets the filter + * @throws NullPointerException if the delegate this was created with is null + */ + public void propertyChange(PropertyChangeEvent event) + { + // Note: Sun does not filter, under the assumption that since + // PropertyChangeSupport unwraps proxys, this method should never be + // called by normal use of listeners. + String name = event == null ? null : event.getPropertyName(); + if (name == null ? propertyName == null : name.equals(propertyName)) + ((PropertyChangeListener) getListener()).propertyChange(event); + } + + /** + * Gets the name of the property this proxy is filtering on. + * + * @return the property name + */ + public String getPropertyName() + { + return propertyName; + } +} // class PropertyChangeListenerProxy |