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 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
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 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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package org.apache.commons.configuration2.event;


Definition of a generic event listener interface.


This event listener interface is used throughout the
Commons Configuration library for reacting on all kinds of supported events. The interface is pretty minimalistic, defining only a single onEvent() method. This simplifies the implementation of custom event listeners and also supports the new language features introduced with Java 8 (EventListener is a functional interface and thus can be represented by a Lambda expression). 
Type parameters:
<T> – the type of events this listener can process
Since:
2.0/**
 * <p>
 * Definition of a generic event listener interface.
 * </p>
 * <p>
 * This event listener interface is used throughout the
 * <em>Commons Configuration</em> library for reacting on all kinds of supported
 * events. The interface is pretty minimalistic, defining only a single
 * {@code onEvent()} method. This simplifies the implementation of custom event
 * listeners and also supports the new language features introduced with Java 8
 * ({@code EventListener} is a functional interface and thus can be represented
 * by a Lambda expression).
 * </p>
 *
 * @since 2.0
 * @param <T> the type of events this listener can process
 */
public interface EventListener<T extends Event>
{
    
Notifies this event listener about the arrival of a new event. Typically, event listeners are registered at an event source providing an EventType. This event type acts as a filter; all events matched by the filter are passed to the listener. The type parameters defined by the EventType class and this interface guarantee that the events delivered to the handler are compatible with the concrete method signature of onEvent(). 
Params:
event – the event/**
     * Notifies this event listener about the arrival of a new event. Typically,
     * event listeners are registered at an event source providing an
     * {@link EventType}. This event type acts as a filter; all events matched
     * by the filter are passed to the listener. The type parameters defined by
     * the {@code EventType} class and this interface guarantee that the events
     * delivered to the handler are compatible with the concrete method
     * signature of {@code onEvent()}.
     *
     * @param event the event
     */
    void onEvent(T event);
}