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 * @param <T> the type of the input to the predicate.
28 * @since 3.0
29 */
30 public final class NullIsTruePredicate<T> extends AbstractPredicate<T> implements PredicateDecorator<T>, Serializable {
31
32 /** Serial version UID */
33 private static final long serialVersionUID = -7625133768987126273L;
34
35 /**
36 * Creates the null true predicate.
37 *
38 * @param <T> the type that the predicate queries
39 * @param predicate the predicate to decorate, not null
40 * @return the predicate
41 * @throws NullPointerException if the predicate is null
42 */
43 public static <T> Predicate<T> nullIsTruePredicate(final Predicate<? super T> predicate) {
44 return new NullIsTruePredicate<>(Objects.requireNonNull(predicate, "predicate"));
45 }
46
47 /** The predicate to decorate */
48 private final Predicate<? super T> iPredicate;
49
50 /**
51 * Constructor that performs no validation.
52 * Use {@code nullIsTruePredicate} if you want that.
53 *
54 * @param predicate the predicate to call after the null check
55 */
56 public NullIsTruePredicate(final Predicate<? super T> predicate) {
57 iPredicate = predicate;
58 }
59
60 /**
61 * Gets the predicate being decorated.
62 *
63 * @return the predicate as the only element in an array
64 * @since 3.1
65 */
66 @Override
67 @SuppressWarnings("unchecked")
68 public Predicate<? super T>[] getPredicates() {
69 return new Predicate[] { iPredicate };
70 }
71
72 /**
73 * Evaluates the predicate returning the result of the decorated predicate
74 * once a null check is performed.
75 *
76 * @param object the input object
77 * @return true if decorated predicate returns true or input is null
78 */
79 @Override
80 public boolean test(final T object) {
81 if (object == null) {
82 return true;
83 }
84 return iPredicate.test(object);
85 }
86
87 }