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
21 import org.apache.commons.collections4.Equator;
22 import org.apache.commons.collections4.Predicate;
23
24 /**
25 * Predicate implementation that returns true if the input is the same object
26 * as the one stored in this predicate by equals.
27 *
28 * @since 3.0
29 */
30 public final class EqualPredicate<T> implements Predicate<T>, Serializable {
31
32 /** Serial version UID */
33 private static final long serialVersionUID = 5633766978029907089L;
34
35 /**
36 * Factory to create the predicate.
37 *
38 * @param <T> the type that the predicate queries
39 * @param object the object to compare to
40 * @return the predicate
41 */
42 public static <T> Predicate<T> equalPredicate(final T object) {
43 if (object == null) {
44 return NullPredicate.nullPredicate();
45 }
46 return new EqualPredicate<>(object);
47 }
48
49 /**
50 * Factory to create the identity predicate.
51 *
52 * @param <T> the type that the predicate queries
53 * @param object the object to compare to
54 * @param equator the equator to use for comparison
55 * @return the predicate
56 * @since 4.0
57 */
58 public static <T> Predicate<T> equalPredicate(final T object, final Equator<T> equator) {
59 if (object == null) {
60 return NullPredicate.nullPredicate();
61 }
62 return new EqualPredicate<>(object, equator);
63 }
64
65 /** The value to compare to */
66 private final T iValue;
67
68 /** The equator to use for comparison */
69 private final Equator<T> equator;
70
71 /**
72 * Constructor that performs no validation.
73 * Use {@code equalPredicate} if you want that.
74 *
75 * @param object the object to compare to
76 */
77 public EqualPredicate(final T object) {
78 // do not use the DefaultEquator to keep backwards compatibility
79 // the DefaultEquator returns also true if the two object references are equal
80 this(object, null);
81 }
82
83 /**
84 * Constructor that performs no validation.
85 * Use {@code equalPredicate} if you want that.
86 *
87 * @param object the object to compare to
88 * @param equator the equator to use for comparison
89 * @since 4.0
90 */
91 public EqualPredicate(final T object, final Equator<T> equator) {
92 iValue = object;
93 this.equator = equator;
94 }
95
96 /**
97 * Evaluates the predicate returning true if the input equals the stored value.
98 *
99 * @param object the input object
100 * @return true if input object equals stored value
101 */
102 @Override
103 public boolean evaluate(final T object) {
104 if (equator != null) {
105 return equator.equate(iValue, object);
106 }
107 return iValue.equals(object);
108 }
109
110 /**
111 * Gets the value.
112 *
113 * @return the value
114 * @since 3.1
115 */
116 public Object getValue() {
117 return iValue;
118 }
119
120 }