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 }