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 }