1 /* 2 * Copyright 2003-2004 Sun Microsystems, Inc. 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. Sun designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, 22 * CA 95054 USA or visit www.sun.com if you need additional information or 23 * have any questions. 24 */ 25 26 package java.lang.annotation; 27 28 /** 29 * The common interface extended by all annotation types. Note that an 30 * interface that manually extends this one does <i>not</i> define 31 * an annotation type. Also note that this interface does not itself 32 * define an annotation type. 33 * 34 * @author Josh Bloch 35 * @since 1.5 36 */ 37 public interface Annotation { 38 /** 39 * Returns true if the specified object represents an annotation 40 * that is logically equivalent to this one. In other words, 41 * returns true if the specified object is an instance of the same 42 * annotation type as this instance, all of whose members are equal 43 * to the corresponding member of this annotation, as defined below: 44 * <ul> 45 * <li>Two corresponding primitive typed members whose values are 46 * <tt>x</tt> and <tt>y</tt> are considered equal if <tt>x == y</tt>, 47 * unless their type is <tt>float</tt> or <tt>double</tt>. 48 * 49 * <li>Two corresponding <tt>float</tt> members whose values 50 * are <tt>x</tt> and <tt>y</tt> are considered equal if 51 * <tt>Float.valueOf(x).equals(Float.valueOf(y))</tt>. 52 * (Unlike the <tt>==</tt> operator, NaN is considered equal 53 * to itself, and <tt>0.0f</tt> unequal to <tt>-0.0f</tt>.) 54 * 55 * <li>Two corresponding <tt>double</tt> members whose values 56 * are <tt>x</tt> and <tt>y</tt> are considered equal if 57 * <tt>Double.valueOf(x).equals(Double.valueOf(y))</tt>. 58 * (Unlike the <tt>==</tt> operator, NaN is considered equal 59 * to itself, and <tt>0.0</tt> unequal to <tt>-0.0</tt>.) 60 * 61 * <li>Two corresponding <tt>String</tt>, <tt>Class</tt>, enum, or 62 * annotation typed members whose values are <tt>x</tt> and <tt>y</tt> 63 * are considered equal if <tt>x.equals(y)</tt>. (Note that this 64 * definition is recursive for annotation typed members.) 65 * 66 * <li>Two corresponding array typed members <tt>x</tt> and <tt>y</tt> 67 * are considered equal if <tt>Arrays.equals(x, y)</tt>, for the 68 * appropriate overloading of {@link java.util.Arrays#equals}. 69 * </ul> 70 * 71 * @return true if the specified object represents an annotation 72 * that is logically equivalent to this one, otherwise false 73 */ 74 boolean equals(Object obj); 75 76 /** 77 * Returns the hash code of this annotation, as defined below: 78 * 79 * <p>The hash code of an annotation is the sum of the hash codes 80 * of its members (including those with default values), as defined 81 * below: 82 * 83 * The hash code of an annotation member is (127 times the hash code 84 * of the member-name as computed by {@link String#hashCode()}) XOR 85 * the hash code of the member-value, as defined below: 86 * 87 * <p>The hash code of a member-value depends on its type: 88 * <ul> 89 * <li>The hash code of a primitive value <tt><i>v</i></tt> is equal to 90 * <tt><i>WrapperType</i>.valueOf(<i>v</i>).hashCode()</tt>, where 91 * <tt><i>WrapperType</i></tt> is the wrapper type corresponding 92 * to the primitive type of <tt><i>v</i></tt> ({@link Byte}, 93 * {@link Character}, {@link Double}, {@link Float}, {@link Integer}, 94 * {@link Long}, {@link Short}, or {@link Boolean}). 95 * 96 * <li>The hash code of a string, enum, class, or annotation member-value 97 I <tt><i>v</i></tt> is computed as by calling 98 * <tt><i>v</i>.hashCode()</tt>. (In the case of annotation 99 * member values, this is a recursive definition.) 100 * 101 * <li>The hash code of an array member-value is computed by calling 102 * the appropriate overloading of 103 * {@link java.util.Arrays#hashCode(long[]) Arrays.hashCode} 104 * on the value. (There is one overloading for each primitive 105 * type, and one for object reference types.) 106 * </ul> 107 * 108 * @return the hash code of this annotation 109 */ 110 int hashCode(); 111 112 /** 113 * Returns a string representation of this annotation. The details 114 * of the representation are implementation-dependent, but the following 115 * may be regarded as typical: 116 * <pre> 117 * @com.acme.util.Name(first=Alfred, middle=E., last=Neuman) 118 * </pre> 119 * 120 * @return a string representation of this annotation 121 */ 122 String toString(); 123 124 /** 125 * Returns the annotation type of this annotation. 126 */ 127 Class<? extends Annotation> annotationType(); 128 }