001    /*
002     *  Licensed to the Apache Software Foundation (ASF) under one or more
003     *  contributor license agreements.  See the NOTICE file distributed with
004     *  this work for additional information regarding copyright ownership.
005     *  The ASF licenses this file to You under the Apache License, Version 2.0
006     *  (the "License"); you may not use this file except in compliance with
007     *  the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     *  Unless required by applicable law or agreed to in writing, software
012     *  distributed under the License is distributed on an "AS IS" BASIS,
013     *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     *  See the License for the specific language governing permissions and
015     *  limitations under the License.
016     */
017    package org.apache.commons.collections.functors;
018    
019    import java.io.Serializable;
020    
021    import org.apache.commons.collections.Closure;
022    
023    /**
024     * Closure implementation that does nothing.
025     * 
026     * @since Commons Collections 3.0
027     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
028     *
029     * @author Stephen Colebourne
030     */
031    public class NOPClosure implements Closure, Serializable {
032    
033        /** Serial version UID */
034        private static final long serialVersionUID = 3518477308466486130L;
035    
036        /** Singleton predicate instance */
037        public static final Closure INSTANCE = new NOPClosure();
038    
039        /**
040         * Factory returning the singleton instance.
041         * 
042         * @return the singleton instance
043         * @since Commons Collections 3.1
044         */
045        public static Closure getInstance() {
046            return INSTANCE;
047        }
048    
049        /**
050         * Constructor
051         */
052        private NOPClosure() {
053            super();
054        }
055    
056        /**
057         * Do nothing.
058         * 
059         * @param input  the input object
060         */
061        public void execute(Object input) {
062            // do nothing
063        }
064    
065    }