svn commit: r1596015 - /commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/event/EventListener.java

[oh...@apache.org]

Author: oheger
Date: Mon May 19 19:54:05 2014
New Revision: 1596015

URL: http://svn.apache.org/r1596015
Log:
Added EventListener interface.

This is a generic interface for reacting on all kinds of events generated by
the [configuration] library.

Added:
    commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/event/EventListener.java

Added: commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/event/EventListener.java
URL: http://svn.apache.org/viewvc/commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/event/EventListener.java?rev=1596015&view=auto
==============================================================================
--- commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/event/EventListener.java (added)
+++ commons/proper/configuration/trunk/src/main/java/org/apache/commons/configuration/event/EventListener.java Mon May 19 19:54:05 2014
@@ -0,0 +1,51 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * 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
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.commons.configuration.event;
+
+/**
+ * <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>
+ *
+ * @version $Id$
+ * @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
+     * {@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);
+}