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 */
017package org.apache.commons.collections4.functors;
018
019import java.io.Serializable;
020
021import org.apache.commons.collections4.Predicate;
022
023/**
024 * Predicate implementation that returns the opposite of the decorated predicate.
025 *
026 * @since 3.0
027 */
028public final class NotPredicate<T> implements PredicateDecorator<T>, Serializable {
029
030    /** Serial version UID */
031    private static final long serialVersionUID = -2654603322338049674L;
032
033    /** The predicate to decorate */
034    private final Predicate<? super T> iPredicate;
035
036    /**
037     * Factory to create the not predicate.
038     *
039     * @param <T> the type that the predicate queries
040     * @param predicate  the predicate to decorate, not null
041     * @return the predicate
042     * @throws NullPointerException if the predicate is null
043     */
044    public static <T> Predicate<T> notPredicate(final Predicate<? super T> predicate) {
045        if (predicate == null) {
046            throw new NullPointerException("Predicate must not be null");
047        }
048        return new NotPredicate<>(predicate);
049    }
050
051    /**
052     * Constructor that performs no validation.
053     * Use <code>notPredicate</code> if you want that.
054     *
055     * @param predicate  the predicate to call after the null check
056     */
057    public NotPredicate(final Predicate<? super T> predicate) {
058        super();
059        iPredicate = predicate;
060    }
061
062    /**
063     * Evaluates the predicate returning the opposite to the stored predicate.
064     *
065     * @param object  the input object
066     * @return true if predicate returns false
067     */
068    @Override
069    public boolean evaluate(final T object) {
070        return !iPredicate.evaluate(object);
071    }
072
073    /**
074     * Gets the predicate being decorated.
075     *
076     * @return the predicate as the only element in an array
077     * @since 3.1
078     */
079    @Override
080    @SuppressWarnings("unchecked")
081    public Predicate<? super T>[] getPredicates() {
082        return new Predicate[] {iPredicate};
083    }
084
085}