Misc. event utils.
git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@966589 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
James W. Carman
parent
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang3.event;
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import java.lang.reflect.InvocationHandler;
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import java.lang.reflect.Method;
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import java.lang.reflect.Proxy;
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import java.util.List;
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import java.util.concurrent.CopyOnWriteArrayList;
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/**
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* An EventListenerSupport object can be used to manage a list of event listeners of a particular type.
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* <p/>
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* To use this class, suppose you want to support ActionEvents. You would do:
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* <pre>
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* public class MyActionEventSource
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* {
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* private EventListenerSupport<ActionListener> actionListeners = EventListenerSupport.create(ActionListener.class);
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* <p/>
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* public void someMethodThatFiresAction()
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* {
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* ActionEvent e = new ActionEvent(this, ActionEvent.ACTION_PERFORMED, "somethingCool");
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* actionListeners.getProxy().actionPerformed(e);
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* }
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* }
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* </pre>
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*
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* @param <L> The event listener type
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*/
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public class EventListenerSupport<L>
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{
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private final List<L> listeners;
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private final L proxy;
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/**
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* Creates an EventListenerSupport object which supports the specified listener type.
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*
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* @param listenerType the listener type
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* @return an EventListenerSupport object which supports the specified listener type
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*/
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public static <T> EventListenerSupport<T> create(Class<T> listenerType)
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{
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return new EventListenerSupport<T>(listenerType);
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}
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/**
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* Creates an EventListenerSupport object which supports the provided listener interface.
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*
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* @param listenerInterface the listener interface
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*/
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public EventListenerSupport(Class<L> listenerInterface)
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{
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this(listenerInterface, Thread.currentThread().getContextClassLoader());
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}
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/**
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* Creates an EventListenerSupport object which supports the provided listener interface using the specified
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* class loader to create the JDK dynamic proxy.
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*
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* @param listenerInterface the listener interface
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* @param classLoader the class loader
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*/
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public EventListenerSupport(Class<L> listenerInterface, ClassLoader classLoader)
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{
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listeners = new CopyOnWriteArrayList<L>();
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proxy = listenerInterface.cast(Proxy.newProxyInstance(classLoader, new Class[]{listenerInterface},
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new ProxyInvocationHandler()));
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}
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/**
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* Returns a proxy object which can be used to call listener methods on all of the registered event listeners.
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*
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* @return a proxy object which can be used to call listener methods on all of the registered event listeners
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*/
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public L fire()
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{
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return proxy;
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}
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//**********************************************************************************************************************
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// Other Methods
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//**********************************************************************************************************************
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/**
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* Registers an event listener.
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*
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* @param listener the event listener
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*/
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public void addListener(L listener)
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{
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listeners.add(0, listener);
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}
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/**
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* Returns the number of registered listeners.
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*
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* @return the number of registered listeners
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*/
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public int getListenerCount()
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{
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return listeners.size();
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}
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/**
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* Unregisters an event listener.
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*
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* @param listener the event listener
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*/
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public void removeListener(L listener)
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{
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listeners.remove(listener);
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}
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/**
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* An invocation handler used to dispatch the event(s) to all the listeners.
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*/
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private class ProxyInvocationHandler implements InvocationHandler
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{
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public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
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{
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for (int i = listeners.size() - 1; i >= 0; --i)
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{
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method.invoke(listeners.get(i), args);
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}
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return null;
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}
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}
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}
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang3.event;
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import org.apache.commons.lang3.reflect.MethodUtils;
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import java.lang.reflect.InvocationHandler;
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import java.lang.reflect.InvocationTargetException;
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import java.lang.reflect.Method;
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import java.lang.reflect.Proxy;
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import java.util.Arrays;
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import java.util.HashSet;
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import java.util.Set;
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public class EventUtils
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{
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public static <L> void addEventListener(Object eventSource, Class<L> listenerType, L listener)
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{
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try
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{
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MethodUtils.invokeMethod(eventSource, "add" + listenerType.getSimpleName(), listener);
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}
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catch (NoSuchMethodException e)
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{
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throw new IllegalArgumentException("Class " + eventSource.getClass() + " does not have an accesible add" + listenerType.getSimpleName() + " method which takes a parameter of type " + listenerType.getClass().getName() + ".");
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}
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catch (IllegalAccessException e)
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{
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throw new IllegalArgumentException("Class " + eventSource.getClass() + " does not have an accesible add" + listenerType.getSimpleName () + " method which takes a parameter of type " + listenerType.getClass().getName() + ".");
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}
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catch (InvocationTargetException e)
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{
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throw new RuntimeException("Unable to add listener.", e.getCause());
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}
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}
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/**
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* Binds an event listener to a specific method on a specific object.
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*
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* @param target the target object
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* @param methodName the name of the method to be called
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* @param eventSource the object which is generating events (JButton, JList, etc.)
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* @param listenerType the listener interface (ActionListener.class, SelectionListener.class, etc.)
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* @param eventTypes the event types (method names) from the listener interface (if none specified, all will be
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* supported)
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*/
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public static void bindEventsToMethod(Object target, String methodName, Object eventSource, Class listenerType, String... eventTypes)
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{
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final Object listener = Proxy.newProxyInstance(target.getClass().getClassLoader(), new Class[] { listenerType }, new EventBindingInvocationHandler(target, methodName, eventTypes));
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addEventListener(eventSource, listenerType, listener);
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}
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private static class EventBindingInvocationHandler implements InvocationHandler
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{
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private final Object target;
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private final String methodName;
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private final Set<String> eventTypes;
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public EventBindingInvocationHandler(final Object target, final String methodName, String[] eventTypes)
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{
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this.target = target;
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this.methodName = methodName;
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this.eventTypes = new HashSet<String>(Arrays.asList(eventTypes));
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}
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public Object invoke(final Object proxy, final Method method, final Object[] parameters) throws Throwable
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{
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if ( eventTypes.isEmpty() || eventTypes.contains(method.getName()))
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{
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if (hasMatchingParametersMethod(method))
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{
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return MethodUtils.invokeMethod(target, methodName, parameters);
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}
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else
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{
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return MethodUtils.invokeMethod(target, methodName, new Object[]{});
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}
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}
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return null;
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}
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private boolean hasMatchingParametersMethod(final Method method)
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{
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return MethodUtils.getAccessibleMethod(target.getClass(), methodName, method.getParameterTypes()) != null;
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}
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}
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}
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang3.event;
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import junit.framework.TestCase;
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import java.awt.event.ActionEvent;
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import java.awt.event.ActionListener;
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import java.util.ArrayList;
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import java.util.List;
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public class EventListenerSupportTest extends TestCase
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{
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public void testEventDispatchOrder()
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{
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EventListenerSupport<ActionListener> listenerSupport = EventListenerSupport.create(ActionListener.class);
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final List<ActionListener> calledListeners = new ArrayList<ActionListener>();
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final ActionListener listener1 = createListener(calledListeners);
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final ActionListener listener2 = createListener(calledListeners);
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listenerSupport.addListener(listener1);
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listenerSupport.addListener(listener2);
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listenerSupport.fire().actionPerformed(new ActionEvent("Hello", 0, "Hello"));
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assertEquals(calledListeners.size(), 2);
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assertSame(calledListeners.get(0), listener1);
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assertSame(calledListeners.get(1), listener2);
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}
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public void testRemoveListenerDuringEvent()
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{
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final EventListenerSupport<ActionListener> listenerSupport = EventListenerSupport.create(ActionListener.class);
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for (int i = 0; i < 10; ++i)
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{
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addDeregisterListener(listenerSupport);
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}
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assertEquals(listenerSupport.getListenerCount(), 10);
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listenerSupport.fire().actionPerformed(new ActionEvent("Hello", 0, "Hello"));
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assertEquals(listenerSupport.getListenerCount(), 0);
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}
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private void addDeregisterListener(final EventListenerSupport<ActionListener> listenerSupport)
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{
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listenerSupport.addListener(new ActionListener()
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{
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public void actionPerformed(ActionEvent e)
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{
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listenerSupport.removeListener(this);
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}
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});
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}
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private ActionListener createListener(final List<ActionListener> calledListeners)
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{
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return new ActionListener()
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{
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public void actionPerformed(ActionEvent e)
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{
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calledListeners.add(this);
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}
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};
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}
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}
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/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package org.apache.commons.lang3.event;
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import junit.framework.TestCase;
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import java.beans.PropertyChangeEvent;
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import java.beans.PropertyChangeListener;
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import java.lang.reflect.InvocationHandler;
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import java.lang.reflect.Method;
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import java.lang.reflect.Proxy;
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import java.util.Map;
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import java.util.TreeMap;
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public class EventUtilsTest extends TestCase
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{
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public void testAddEventListener()
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{
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final PropertyChangeSource src = new PropertyChangeSource();
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EventCountingInvociationHandler handler = new EventCountingInvociationHandler();
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PropertyChangeListener listener = handler.createListener(PropertyChangeListener.class);
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assertEquals(0, handler.getEventCount("propertyChange"));
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EventUtils.addEventListener(src, PropertyChangeListener.class, listener);
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assertEquals(0, handler.getEventCount("propertyChange"));
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src.setProperty("newValue");
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assertEquals(1, handler.getEventCount("propertyChange"));
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}
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public void testBindEventsToMethod()
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{
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final PropertyChangeSource src = new PropertyChangeSource();
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final EventCounter counter = new EventCounter();
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EventUtils.bindEventsToMethod(counter, "eventOccurred", src, PropertyChangeListener.class);
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assertEquals(0, counter.getCount());
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src.setProperty("newValue");
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assertEquals(1, counter.getCount());
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}
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public static class EventCounter
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{
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private int count;
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public void eventOccurred()
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{
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count++;
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}
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public int getCount()
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{
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return count;
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}
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}
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private static class EventCountingInvociationHandler implements InvocationHandler
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{
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private Map<String, Integer> eventCounts = new TreeMap<String, Integer>();
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public <L> L createListener(Class<L> listenerType)
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{
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return listenerType.cast(Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(),
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new Class[]{listenerType},
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this));
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}
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public int getEventCount(String eventName)
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{
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Integer count = eventCounts.get(eventName);
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return count == null ? 0 : count;
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}
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public Object invoke(Object proxy, Method method, Object[] args) throws Throwable
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{
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Integer count = eventCounts.get(method.getName());
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if (count == null)
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{
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eventCounts.put(method.getName(), 1);
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}
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else
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{
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eventCounts.put(method.getName(), count + 1);
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}
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return null;
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}
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}
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public static class PropertyChangeSource
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{
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private EventListenerSupport<PropertyChangeListener> listeners = EventListenerSupport.create(PropertyChangeListener.class);
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private String property;
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public void setProperty(String property)
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{
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String oldValue = this.property;
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this.property = property;
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listeners.fire().propertyChange(new PropertyChangeEvent(this, "property", "oldValue", property));
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}
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public void addPropertyChangeListener(PropertyChangeListener listener)
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{
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listeners.addListener(listener);
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}
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public void removePropertyChangeListener(PropertyChangeListener listener)
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{
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listeners.removeListener(listener);
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}
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}
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}
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