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