1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 */ 17 package org.apache.commons.collections4.functors; 18 19 import java.io.Serializable; 20 import java.util.Objects; 21 22 import org.apache.commons.collections4.Predicate; 23 24 /** 25 * Predicate implementation that returns true if the input is null. 26 * 27 * @since 3.0 28 */ 29 public final class NullIsTruePredicate<T> implements PredicateDecorator<T>, Serializable { 30 31 /** Serial version UID */ 32 private static final long serialVersionUID = -7625133768987126273L; 33 34 /** 35 * Factory to create the null true predicate. 36 * 37 * @param <T> the type that the predicate queries 38 * @param predicate the predicate to decorate, not null 39 * @return the predicate 40 * @throws NullPointerException if the predicate is null 41 */ 42 public static <T> Predicate<T> nullIsTruePredicate(final Predicate<? super T> predicate) { 43 return new NullIsTruePredicate<>(Objects.requireNonNull(predicate, "predicate")); 44 } 45 46 /** The predicate to decorate */ 47 private final Predicate<? super T> iPredicate; 48 49 /** 50 * Constructor that performs no validation. 51 * Use {@code nullIsTruePredicate} if you want that. 52 * 53 * @param predicate the predicate to call after the null check 54 */ 55 public NullIsTruePredicate(final Predicate<? super T> predicate) { 56 iPredicate = predicate; 57 } 58 59 /** 60 * Evaluates the predicate returning the result of the decorated predicate 61 * once a null check is performed. 62 * 63 * @param object the input object 64 * @return true if decorated predicate returns true or input is null 65 */ 66 @Override 67 public boolean evaluate(final T object) { 68 if (object == null) { 69 return true; 70 } 71 return iPredicate.evaluate(object); 72 } 73 74 /** 75 * Gets the predicate being decorated. 76 * 77 * @return the predicate as the only element in an array 78 * @since 3.1 79 */ 80 @Override 81 @SuppressWarnings("unchecked") 82 public Predicate<? super T>[] getPredicates() { 83 return new Predicate[] { iPredicate }; 84 } 85 86 }