1 /* Annotation.java - Base interface for all annotations 2 Copyright (C) 2004 Free Software Foundation 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 package java.lang.annotation; 39 40 /** 41 * This is the common interface for all annotations. Note that classes 42 * that implement this class manually are not classed as annotations, and 43 * that this interface does not define an annotation type in itself. 44 * 45 * @author Tom Tromey (tromey@redhat.com) 46 * @author Andrew John Hughes (gnu_andrew@member.fsf.org) 47 * @since 1.5 48 */ 49 public interface Annotation 50 { 51 52 /** 53 * Returns the type of this annotation. 54 * 55 * @return the class of which this annotation is an instance. 56 */ annotationType()57 Class<? extends Annotation> annotationType(); 58 59 /** 60 * <p> 61 * Returns true if the supplied object is equivalent to this annotation. 62 * For this property to hold, the following must be true of <code>o</code>: 63 * </p> 64 * <ul> 65 * <li>The object is also an instance of the same annotation type.</li> 66 * <li>The members of the supplied annotation are equal to those of this 67 * annotation, according to the following: 68 * <ul> 69 * <li>If the members are <code>float</code>s, then, for floats 70 * <code>x</code> and <code>y</code>, 71 * <code>Float.valueOf(x).equals(Float.valueOf(y)</code> must return 72 * true. This differs from the usual (<code>==</code>) comparison 73 * in that <code>NaN</code> is considered equal to itself and positive 74 * and negative zero are seen as different.</li> 75 * <li>Likewise, if the members are <code>double</code>s, then, for doubles 76 * <code>x</code> and <code>y</code>, 77 * <code>Double.valueOf(x).equals(Double.valueOf(y)</code> must return 78 * true. This differs from the usual (<code>==</code>) comparison 79 * in that <code>NaN</code> is considered equal to itself and positive 80 * and negative zero are seen as different.</li> 81 * <li>Strings, classes, enumerations and annotations are considered 82 * equal according to the <code>equals()</code> implementation for these 83 * types.</li> 84 * <li>Arrays are considered equal according to <code>Arrays.equals()</code> 85 * </li> 86 * <li>Any remaining types are considered equal using <code>==</code>.</li> 87 * </li> 88 * </ul> 89 * 90 * @param o the object to compare with this annotation. 91 * @return true if the supplied object is an annotation with equivalent 92 * members. 93 */ equals(Object o)94 boolean equals(Object o); 95 96 /** 97 * <p> 98 * Returns the hash code of the annotation. This is computed as the 99 * sum of the hash codes of the annotation's members. 100 * </p> 101 * <p> 102 * The hash code of a member of the annotation is the result of XORing 103 * the hash code of its value with the result of multiplying the hash code 104 * of its name by 127. Formally, if the value is <code>v</code> and the 105 * name is <code>n</code>, the hash code of the member is 106 * v.hashCode() XOR (127 * String.hashCode(n)). <code>v.hashCode()</code> 107 * is defined as follows: 108 * </p> 109 * <ul> 110 * <li>The hash code of a primitive value (i.e. <code>byte</code>, 111 * <code>char</code>, <code>double</code>, <code>float</code>, 112 * <code>int</code>, <code>long</code>, <code>short</code> and 113 * <code>boolean</code>) is the hash code obtained from its corresponding 114 * wrapper class using <code>valueOf(v).hashCode()</code>, where 115 * <code>v</code> is the primitive value.</li> 116 * <li>The hash code of an enumeration, string, class or other annotation 117 * is obtained using <code>v.hashCode()</code>.</li> 118 * <li>The hash code of an array is computed using 119 * <code>Arrays.hashCode(v)</code>.</li> 120 * </ul> 121 * 122 * @return the hash code of the annotation, computed as the sum of its 123 * member hashcodes. 124 */ hashCode()125 int hashCode(); 126 127 /** 128 * Returns a textual representation of the annotation. This is 129 * implementation-dependent, but is expected to include the classname 130 * and the names and values of each member. 131 * 132 * @return a textual representation of the annotation. 133 */ toString()134 String toString(); 135 } 136