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