1 /* 2 * Copyright (c) 2003, 2020, 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 interface is applicable. The 30 * declaration contexts and type contexts in which an annotation interface may 31 * be applicable are specified in JLS {@jls 9.6.4.1}, and denoted in source code by 32 * enum constants of {@link ElementType java.lang.annotation.ElementType}. 33 * 34 * <p>If an {@code @Target} meta-annotation is not present on an annotation 35 * interface {@code T}, then an annotation of type {@code T} may be written as 36 * a modifier for any 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 {@jls 9.7.4}. 41 * 42 * <p>For example, this {@code @Target} meta-annotation indicates that the 43 * declared interface is itself a meta-annotation interface. It can only be 44 * used on annotation interface 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 class or 53 * interface is intended solely for use as a member class or interface in 54 * complex annotation interface declarations. It cannot be used to annotate 55 * anything directly: 56 * <pre> 57 * @Target({}) 58 * public @interface MemberInterface { 59 * ... 60 * } 61 * </pre> 62 * 63 * <p>It is a compile-time error for a single {@code ElementType} constant to 64 * appear more than once in an {@code @Target} annotation. For example, the 65 * following {@code @Target} meta-annotation is illegal: 66 * <pre> 67 * @Target({ElementType.FIELD, ElementType.METHOD, ElementType.FIELD}) 68 * public @interface Bogus { 69 * ... 70 * } 71 * </pre> 72 * 73 * @since 1.5 74 * @jls 9.6.4.1 @Target 75 * @jls 9.7.4 Where Annotations May Appear 76 * @jls 9.7.5 Multiple Annotations of the Same Interface 77 */ 78 @Documented 79 @Retention(RetentionPolicy.RUNTIME) 80 @Target(ElementType.ANNOTATION_TYPE) 81 public @interface Target { 82 /** 83 * Returns an array of the kinds of elements an annotation interface 84 * can be applied to. 85 * @return an array of the kinds of elements an annotation interface 86 * can be applied to 87 */ value()88 ElementType[] value(); 89 } 90