1 /*
2 * Portions of this software was developed by employees of the National Institute
3 * of Standards and Technology (NIST), an agency of the Federal Government and is
4 * being made available as a public service. Pursuant to title 17 United States
5 * Code Section 105, works of NIST employees are not subject to copyright
6 * protection in the United States. This software may be subject to foreign
7 * copyright. Permission in the United States and in foreign countries, to the
8 * extent that NIST may hold copyright, to use, copy, modify, create derivative
9 * works, and distribute this software and its documentation without fee is hereby
10 * granted on a non-exclusive basis, provided that this notice and disclaimer
11 * of warranty appears in all copies.
12 *
13 * THE SOFTWARE IS PROVIDED 'AS IS' WITHOUT ANY WARRANTY OF ANY KIND, EITHER
14 * EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING, BUT NOT LIMITED TO, ANY WARRANTY
15 * THAT THE SOFTWARE WILL CONFORM TO SPECIFICATIONS, ANY IMPLIED WARRANTIES OF
16 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FREEDOM FROM
17 * INFRINGEMENT, AND ANY WARRANTY THAT THE DOCUMENTATION WILL CONFORM TO THE
18 * SOFTWARE, OR ANY WARRANTY THAT THE SOFTWARE WILL BE ERROR FREE. IN NO EVENT
19 * SHALL NIST BE LIABLE FOR ANY DAMAGES, INCLUDING, BUT NOT LIMITED TO, DIRECT,
20 * INDIRECT, SPECIAL OR CONSEQUENTIAL DAMAGES, ARISING OUT OF, RESULTING FROM,
21 * OR IN ANY WAY CONNECTED WITH THIS SOFTWARE, WHETHER OR NOT BASED UPON WARRANTY,
22 * CONTRACT, TORT, OR OTHERWISE, WHETHER OR NOT INJURY WAS SUSTAINED BY PERSONS OR
23 * PROPERTY OR OTHERWISE, AND WHETHER OR NOT LOSS WAS SUSTAINED FROM, OR AROSE OUT
24 * OF THE RESULTS OF, OR USE OF, THE SOFTWARE OR SERVICES PROVIDED HEREUNDER.
25 */
26
27 package gov.nist.secauto.metaschema.core.util;
28
29 import java.util.Objects;
30 import java.util.stream.Stream;
31
32 import edu.umd.cs.findbugs.annotations.NonNull;
33
34 public final class ObjectUtils {
35 private ObjectUtils() {
36 // disable construction
37 }
38
39 /**
40 * Assert that the provided object is not {@code null}.
41 * <p>
42 * This method sets the expectation that the provided object is not {@code null}
43 * in cases where a non-null value is required.
44 *
45 * @param <T>
46 * the object type
47 * @param obj
48 * the object
49 * @return the object
50 */
51 @NonNull
52 public static <T> T notNull(T obj) {
53 assert obj != null;
54 return obj;
55 }
56
57 /**
58 * Require a non-null value.
59 *
60 * @param <T>
61 * the type of the reference
62 * @param obj
63 * the object reference to check for nullity
64 * @return {@code obj} if not {@code null}
65 * @throws NullPointerException
66 * if {@code obj} is {@code null}
67 */
68 @NonNull
69 public static <T> T requireNonNull(T obj) {
70 if (obj == null) {
71 throw new NullPointerException(); // NOPMD
72 }
73 return obj;
74 }
75
76 /**
77 * Require a non-null value.
78 *
79 * @param <T>
80 * the type of the reference
81 * @param obj
82 * the object reference to check for nullity
83 * @param message
84 * detail message to be used in the event that a {@code
85 * NullPointerException} is thrown
86 * @return {@code obj} if not {@code null}
87 * @throws NullPointerException
88 * if {@code obj} is {@code null}
89 */
90 @NonNull
91 public static <T> T requireNonNull(T obj, @NonNull String message) {
92 if (obj == null) {
93 throw new NullPointerException(message); // NOPMD
94 }
95 return obj;
96 }
97
98 /**
99 * A filter used to remove null items from a stream.
100 *
101 * @param <T>
102 * the item type
103 * @param item
104 * the item to filter
105 * @return the item as a steam or an empty stream if the item is {@code null}
106 */
107 @SuppressWarnings("null")
108 @NonNull
109 public static <T> Stream<T> filterNull(T item) {
110 return Objects.nonNull(item) ? Stream.of(item) : Stream.empty();
111 }
112
113 @SuppressWarnings("unchecked")
114 @NonNull
115 public static <T> T asType(@NonNull Object obj) {
116 return (T) obj;
117 }
118
119 @SuppressWarnings("unchecked")
120 public static <T> T asNullableType(Object obj) {
121 return (T) obj;
122 }
123 }