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