    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}