1/*
2 * Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26package java.lang.annotation;
27
28/**
29 * Indicates the contexts in which an annotation type is applicable. The
30 * declaration contexts and type contexts in which an annotation type may be
31 * applicable are specified in JLS 9.6.4.1, and denoted in source code by enum
32 * constants of {@link ElementType java.lang.annotation.ElementType}.
33 *
34 * <p>If an {@code @Target} meta-annotation is not present on an annotation type
35 * {@code T} , then an annotation of type {@code T} may be written as a
36 * modifier for any declaration except a type parameter declaration.
37 *
38 * <p>If an {@code @Target} meta-annotation is present, the compiler will enforce
39 * the usage restrictions indicated by {@code ElementType}
40 * enum constants, in line with JLS 9.7.4.
41 *
42 * <p>For example, this {@code @Target} meta-annotation indicates that the
43 * declared type is itself a meta-annotation type.  It can only be used on
44 * annotation type declarations:
45 * <pre>
46 *    &#064;Target(ElementType.ANNOTATION_TYPE)
47 *    public &#064;interface MetaAnnotationType {
48 *        ...
49 *    }
50 * </pre>
51 *
52 * <p>This {@code @Target} meta-annotation indicates that the declared type is
53 * intended solely for use as a member type in complex annotation type
54 * declarations.  It cannot be used to annotate anything directly:
55 * <pre>
56 *    &#064;Target({})
57 *    public &#064;interface MemberType {
58 *        ...
59 *    }
60 * </pre>
61 *
62 * <p>It is a compile-time error for a single {@code ElementType} constant to
63 * appear more than once in an {@code @Target} annotation.  For example, the
64 * following {@code @Target} meta-annotation is illegal:
65 * <pre>
66 *    &#064;Target({ElementType.FIELD, ElementType.METHOD, ElementType.FIELD})
67 *    public &#064;interface Bogus {
68 *        ...
69 *    }
70 * </pre>
71 *
72 * @since 1.5
73 * @jls 9.6.4.1 @Target
74 * @jls 9.7.4 Where Annotations May Appear
75 */
76@Documented
77@Retention(RetentionPolicy.RUNTIME)
78@Target(ElementType.ANNOTATION_TYPE)
79public @interface Target {
80    /**
81     * Returns an array of the kinds of elements an annotation type
82     * can be applied to.
83     * @return an array of the kinds of elements an annotation type
84     * can be applied to
85     */
86    ElementType[] value();
87}
88