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.Predicate;
022    
023    /**
024     * Predicate implementation that returns true if the input is an instanceof
025     * the type stored in this predicate.
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 InstanceofPredicate implements Predicate, Serializable {
033    
034        /** Serial version UID */
035        private static final long serialVersionUID = -6682656911025165584L;
036    
037        /** The type to compare to */
038        private final Class iType;
039        
040        /**
041         * Factory to create the identity predicate.
042         * 
043         * @param type  the type to check for, may not be null
044         * @return the predicate
045         * @throws IllegalArgumentException if the class is null
046         */
047        public static Predicate getInstance(Class type) {
048            if (type == null) {
049                throw new IllegalArgumentException("The type to check instanceof must not be null");
050            }
051            return new InstanceofPredicate(type);
052        }
053    
054        /**
055         * Constructor that performs no validation.
056         * Use <code>getInstance</code> if you want that.
057         * 
058         * @param type  the type to check for
059         */
060        public InstanceofPredicate(Class type) {
061            super();
062            iType = type;
063        }
064    
065        /**
066         * Evaluates the predicate returning true if the input object is of the correct type.
067         * 
068         * @param object  the input object
069         * @return true if input is of stored type
070         */
071        public boolean evaluate(Object object) {
072            return (iType.isInstance(object));
073        }
074    
075        /**
076         * Gets the type to compare to.
077         * 
078         * @return the type
079         * @since Commons Collections 3.1
080         */
081        public Class getType() {
082            return iType;
083        }
084    
085    }