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.FunctorException;
022    import org.apache.commons.collections.Predicate;
023    
024    /**
025     * Predicate implementation that throws an exception if the input is null.
026     * 
027     * @since Commons Collections 3.0
028     * @version $Revision: 646777 $ $Date: 2008-04-10 13:33:15 +0100 (Thu, 10 Apr 2008) $
029     *
030     * @author Stephen Colebourne
031     */
032    public final class NullIsExceptionPredicate implements Predicate, PredicateDecorator, Serializable {
033    
034        /** Serial version UID */
035        private static final long serialVersionUID = 3243449850504576071L;
036        
037        /** The predicate to decorate */
038        private final Predicate iPredicate;
039        
040        /**
041         * Factory to create the null exception predicate.
042         * 
043         * @param predicate  the predicate to decorate, not null
044         * @return the predicate
045         * @throws IllegalArgumentException if the predicate is null
046         */
047        public static Predicate getInstance(Predicate predicate) {
048            if (predicate == null) {
049                throw new IllegalArgumentException("Predicate must not be null");
050            }
051            return new NullIsExceptionPredicate(predicate);
052        }
053    
054        /**
055         * Constructor that performs no validation.
056         * Use <code>getInstance</code> if you want that.
057         * 
058         * @param predicate  the predicate to call after the null check
059         */
060        public NullIsExceptionPredicate(Predicate predicate) {
061            super();
062            iPredicate = predicate;
063        }
064    
065        /**
066         * Evaluates the predicate returning the result of the decorated predicate
067         * once a null check is performed.
068         * 
069         * @param object  the input object
070         * @return true if decorated predicate returns true
071         * @throws FunctorException if input is null
072         */
073        public boolean evaluate(Object object) {
074            if (object == null) {
075                throw new FunctorException("Input Object must not be null");
076            }
077            return iPredicate.evaluate(object);
078        }
079    
080        /**
081         * Gets the predicate being decorated.
082         * 
083         * @return the predicate as the only element in an array
084         * @since Commons Collections 3.1
085         */
086        public Predicate[] getPredicates() {
087            return new Predicate[] {iPredicate};
088        }
089    
090    }