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.functor.core;
18
19 import java.io.Serializable;
20
21 import org.apache.commons.functor.BinaryPredicate;
22 import org.apache.commons.functor.UnaryPredicate;
23 import org.apache.commons.functor.adapter.IgnoreLeftPredicate;
24 import org.apache.commons.functor.adapter.IgnoreRightPredicate;
25
26 /**
27 * {@link #test Tests}
28 * <code>false</code> iff its argument
29 * is <code>null</code>.
30 *
31 * @param <T> the argument type.
32 * @version $Revision: 1345136 $ $Date: 2012-06-01 09:47:06 -0300 (Fri, 01 Jun 2012) $
33 */
34 public final class IsNotNull<T> implements UnaryPredicate<T>, Serializable {
35
36 // static attributes
37 // ------------------------------------------------------------------------
38 /**
39 * Basic IsNotNull instance.
40 */
41 public static final IsNotNull<Object> INSTANCE = IsNotNull.<Object>instance();
42
43 /**
44 * Left-handed BinaryPredicate.
45 */
46 public static final BinaryPredicate<Object, Object> LEFT = IsNotNull.<Object>left();
47
48 /**
49 * Right-handed BinaryPredicate.
50 */
51 public static final BinaryPredicate<Object, Object> RIGHT = IsNotNull.<Object>right();
52
53 /**
54 * serialVersionUID declaration.
55 */
56 private static final long serialVersionUID = -6856387958371590330L;
57
58 // constructor
59 // ------------------------------------------------------------------------
60 /**
61 * Create a new IsNotNull.
62 */
63 public IsNotNull() {
64 }
65
66 // predicate interface
67 // ------------------------------------------------------------------------
68 /**
69 * {@inheritDoc}
70 */
71 public boolean test(Object obj) {
72 return (null != obj);
73 }
74
75 /**
76 * {@inheritDoc}
77 */
78 @Override
79 public boolean equals(Object that) {
80 return that instanceof IsNotNull<?>;
81 }
82
83 /**
84 * {@inheritDoc}
85 */
86 @Override
87 public int hashCode() {
88 return "IsNotNull".hashCode();
89 }
90
91 /**
92 * {@inheritDoc}
93 */
94 @Override
95 public String toString() {
96 return "IsNotNull";
97 }
98
99 // static methods
100 // ------------------------------------------------------------------------
101 /**
102 * Get an IsNotNull instance.
103 * @param <T> the predicate argument type.
104 * @return IsNotNull
105 */
106 public static <T> IsNotNull<T> instance() {
107 return new IsNotNull<T>();
108 }
109
110 /**
111 * Get a BinaryPredicate that matches if the left argument is not null.
112 * @param <A> the left {@code BinaryPredicate} argument type.
113 * @return BinaryPredicate<A, Object>
114 */
115 public static <A> BinaryPredicate<A, Object> left() {
116 return IgnoreRightPredicate.adapt(new IsNotNull<A>());
117 }
118
119 /**
120 * Get a BinaryPredicate that matches if the right argument is null.
121 * @param <A> the right {@code BinaryPredicate} argument type.
122 * @return BinaryPredicate<Object, A>
123 */
124 public static <A> BinaryPredicate<Object, A> right() {
125 return IgnoreLeftPredicate.adapt(new IsNotNull<A>());
126 }
127
128 }