blob: 75a31bba6fb57f69f67701706f3fef18469ebb74 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
|
/*
* Copyright (C) 2015, Google Inc. and others
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0 which is available at
* https://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package org.eclipse.jgit.annotations;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.LOCAL_VARIABLE;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Marks types that can hold the value {@code null} at run time.
* <p>
* Unlike {@code org.eclipse.jdt.annotation.Nullable}, this has run-time
* retention, allowing the annotation to be recognized by
* <a href="https://github.com/google/guice/wiki/UseNullable">Guice</a>. Unlike
* {@code javax.annotation.Nullable}, this does not involve importing new classes
* to a standard (Java EE) package, so it can be deployed in an OSGi container
* without running into
* <a href="http://wiki.osgi.org/wiki/Split_Packages">split-package</a>
* <a href="https://gerrit-review.googlesource.com/50112">problems</a>.
* <p>
* You can use this annotation to qualify a type in a method signature or local
* variable declaration. The entity whose type has this annotation is allowed to
* hold the value {@code null} at run time. This allows annotation based null
* analysis to infer that
* <ul>
* <li>Binding a {@code null} value to the entity is legal.
* <li>Dereferencing the entity is unsafe and can trigger a
* {@code NullPointerException}.
* </ul>
* <p>
* To avoid a dependency on Java 8, this annotation does not use
* {@link Target @Target} {@code TYPE_USE}. That may change when JGit starts
* requiring Java 8.
* <p>
* <b>Warning:</b> Please do not use this annotation on arrays. Different
* annotation processors treat {@code @Nullable Object[]} differently: some
* treat it as an array of nullable objects, for consistency with versions of
* {@code Nullable} defined with {@code @Target} {@code TYPE_USE}, while others
* treat it as a nullable array of objects. JGit therefore avoids using this
* annotation on arrays altogether.
*
* @see <a href=
* "http://types.cs.washington.edu/checker-framework/current/checker-framework-manual.html#faq-array-syntax-meaning">
* The checker-framework manual</a>
* @since 4.2
*/
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ FIELD, METHOD, PARAMETER, LOCAL_VARIABLE })
public @interface Nullable {
// marker annotation with no members
}
|
