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1   /*
2    * Copyright (c) 1998, 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 com.sun.jdi;
27  
28  /**
29   * A class or instance variable in the target VM.
30   * See {@link TypeComponent}
31   * for general information about Field and Method mirrors.
32   *
33   * @see ObjectReference
34   * @see ReferenceType
35   *
36   * @author Robert Field
37   * @author Gordon Hirsch
38   * @author James McIlree
39   * @since  1.3
40   */
41  @jdk.Exported
42  public interface Field extends TypeComponent, Comparable<Field> {
43  
44      /**
45       * Returns a text representation of the type
46       * of this field.
47       * Where the type is the type specified in the declaration
48       * of this field.
49       * <P>
50       * This type name is always available even if
51       * the type has not yet been created or loaded.
52       *
53       * @return a String representing the
54       * type of this field.
55       */
56      String typeName();
57  
58      /**
59       * Returns the type of this field.
60       * Where the type is the type specified in the declaration
61       * of this field.
62       * <P>
63       * For example, if a target class defines:
64       * <PRE>
65       *    short s;
66       *    Date d;
67       *    byte[] ba;</PRE>
68       * And the JDI client defines these <CODE>Field</CODE> objects:
69       * <PRE>
70       *    Field sField = targetClass.fieldByName("s");
71       *    Field dField = targetClass.fieldByName("d");
72       *    Field baField = targetClass.fieldByName("ba");</PRE>
73       * to mirror the corresponding fields, then <CODE>sField.type()</CODE>
74       * is a {@link ShortType}, <CODE>dField.type()</CODE> is the
75       * {@link ReferenceType} for <CODE>java.util.Date</CODE> and
76       * <CODE>((ArrayType)(baField.type())).componentType()</CODE> is a
77       * {@link ByteType}.
78       * <P>
79       * Note: if the type of this field is a reference type (class,
80       * interface, or array) and it has not been created or loaded
81       * by the declaring type's class loader - that is,
82       * {@link TypeComponent#declaringType <CODE>declaringType()</CODE>}
83       * <CODE>.classLoader()</CODE>,
84       * then ClassNotLoadedException will be thrown.
85       * Also, a reference type may have been loaded but not yet prepared,
86       * in which case the type will be returned
87       * but attempts to perform some operations on the returned type
88       * (e.g. {@link ReferenceType#fields() fields()}) will throw
89       * a {@link ClassNotPreparedException}.
90       * Use {@link ReferenceType#isPrepared()} to determine if
91       * a reference type is prepared.
92       *
93       * @see Type
94       * @return the {@link Type} of this field.
95       * @throws ClassNotLoadedException if the type has not yet been loaded
96       * or created through the appropriate class loader.
97       */
98      Type type() throws ClassNotLoadedException;
99  
100     /**
101      * Determine if this is a transient field.
102      *
103      * @return <code>true</code> if this field is transient; false otherwise.
104      */
105     boolean isTransient();
106 
107     /**
108      * Determine if this is a volatile field.
109      *
110      * @return <code>true</code> if this field is volatile; false otherwise.
111      */
112     boolean isVolatile();
113 
114     /**
115      * Determine if this is a field that represents an enum constant.
116      * @return <code>true</code> if this field represents an enum constant;
117      * false otherwise.
118      */
119     boolean isEnumConstant();
120 
121     /**
122      * Compares the specified Object with this field for equality.
123      *
124      * @return true if the Object is a Field and if both
125      * mirror the same field (declared in the same class or interface, in
126      * the same VM).
127      */
128     boolean equals(Object obj);
129 
130     /**
131      * Returns the hash code value for this Field.
132      *
133      * @return the integer hash code
134      */
135     int hashCode();
136 }