1 /*
   2  * Copyright (c) 2005, 2012, 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 javax.lang.model.element;
  27 
  28 /**
  29  * Represents a value of an annotation type element.
  30  * A value is of one of the following types:
  31  * <ul><li> a wrapper class (such as {@link Integer}) for a primitive type
  32  *     <li> {@code String}
  33  *     <li> {@code TypeMirror}
  34  *     <li> {@code VariableElement} (representing an enum constant)
  35  *     <li> {@code AnnotationMirror}
  36  *     <li> {@code List<? extends AnnotationValue>}
  37  *              (representing the elements, in declared order, if the value is an array)
  38  * </ul>
  39  *
  40  * @author Joseph D. Darcy
  41  * @author Scott Seligman
  42  * @author Peter von der Ah&eacute;
  43  * @since 1.6
  44  */
  45 public interface AnnotationValue {
  46 
  47     /**
  48      * Returns the value.
  49      *
  50      * @return the value
  51      */
  52     Object getValue();
  53 
  54     /**
  55      * Returns a string representation of this value.
  56      * This is returned in a form suitable for representing this value
  57      * in the source code of an annotation.
  58      *
  59      * @return a string representation of this value
  60      */
  61     String toString();
  62 
  63     /**
  64      * Returns {@code true} if the other object is also an {@code
  65      * AnnotationValue} and its {@linkplain getValue
  66      * value} is equal to this {@code AnnotationValue}'s value.
  67      *
  68      * @return {@code true} if the argument is an equal {@code
  69      * AnnotationValue}; {@code false} otherwise.
  70      */ 
  71     @Override
  72     boolean equals(Object o);
  73 
  74     /**
  75      * Returns the hash code of this {@code
  76      * AnnotationValues}'s {@linkplain getValue value}.
  77      * @reurn the hashCode of the {@code AnnotationValues}'s value
  78      */
  79     @Override
  80     int hashCode();
  81 
  82     /**
  83      * Applies a visitor to this value.
  84      *
  85      * @param <R> the return type of the visitor's methods
  86      * @param <P> the type of the additional parameter to the visitor's methods
  87      * @param v   the visitor operating on this value
  88      * @param p   additional parameter to the visitor
  89      * @return a visitor-specified result
  90      */
  91     <R, P> R accept(AnnotationValueVisitor<R, P> v, P p);
  92 }