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 26 package 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 * @Target(ElementType.ANNOTATION_TYPE) 47 * public @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 * @Target({}) 57 * public @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 * @Target({ElementType.FIELD, ElementType.METHOD, ElementType.FIELD}) 67 * public @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) 79 public @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 */ value()86 ElementType[] value(); 87 } 88