Java tutorial
/* * Copyright 2001-2004 The Apache Software Foundation * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.commons.collections.functors; import java.io.Serializable; import org.apache.commons.collections.Predicate; /** * Predicate implementation that returns the opposite of the decorated predicate. * * @since Commons Collections 3.0 * @version $Revision: 1.6 $ $Date: 2004/05/31 16:43:17 $ * * @author Stephen Colebourne */ public final class NotPredicate implements Predicate, PredicateDecorator, Serializable { /** Serial version UID */ static final long serialVersionUID = -2654603322338049674L; /** The predicate to decorate */ private final Predicate iPredicate; /** * Factory to create the not predicate. * * @param predicate the predicate to decorate, not null * @return the predicate * @throws IllegalArgumentException if the predicate is null */ public static Predicate getInstance(Predicate predicate) { if (predicate == null) { throw new IllegalArgumentException("Predicate must not be null"); } return new NotPredicate(predicate); } /** * Constructor that performs no validation. * Use <code>getInstance</code> if you want that. * * @param predicate the predicate to call after the null check */ public NotPredicate(Predicate predicate) { super(); iPredicate = predicate; } /** * Evaluates the predicate returning the opposite to the stored predicate. * * @param object the input object * @return true if predicate returns false */ public boolean evaluate(Object object) { return !(iPredicate.evaluate(object)); } /** * Gets the predicate being decorated. * * @return the predicate as the only element in an array * @since Commons Collections 3.1 */ public Predicate[] getPredicates() { return new Predicate[] { iPredicate }; } }