1 /*
2 * Copyright (c) 1995, 2004, 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;
27
28 import java.io.IOException;
29 import java.io.ObjectInputStream;
30 import java.io.ObjectOutputStream;
31 import java.io.ObjectStreamField;
32
33 /**
34 * Thrown when an application tries to load in a class through its
35 * string name using:
36 * <ul>
37 * <li>The <code>forName</code> method in class <code>Class</code>.
38 * <li>The <code>findSystemClass</code> method in class
39 * <code>ClassLoader</code> .
40 * <li>The <code>loadClass</code> method in class <code>ClassLoader</code>.
41 * </ul>
42 * <p>
43 * but no definition for the class with the specified name could be found.
44 *
45 * <p>As of release 1.4, this exception has been retrofitted to conform to
46 * the general purpose exception-chaining mechanism. The "optional exception
47 * that was raised while loading the class" that may be provided at
48 * construction time and accessed via the {@link #getException()} method is
49 * now known as the <i>cause</i>, and may be accessed via the {@link
50 * Throwable#getCause()} method, as well as the aforementioned "legacy method."
51 *
52 * @author unascribed
53 * @see java.lang.Class#forName(java.lang.String)
54 * @see java.lang.ClassLoader#findSystemClass(java.lang.String)
55 * @see java.lang.ClassLoader#loadClass(java.lang.String, boolean)
56 * @since 1.0
57 */
58 public class ClassNotFoundException extends ReflectiveOperationException {
59 /**
60 * use serialVersionUID from JDK 1.1.X for interoperability
61 */
62 @java.io.Serial
63 private static final long serialVersionUID = 9176873029745254542L;
64
65 /**
66 * Constructs a <code>ClassNotFoundException</code> with no detail message.
67 */
68 public ClassNotFoundException() {
69 super((Throwable)null); // Disallow initCause
70 }
71
72 /**
73 * Constructs a <code>ClassNotFoundException</code> with the
74 * specified detail message.
75 *
76 * @param s the detail message.
77 */
78 public ClassNotFoundException(String s) {
79 super(s, null); // Disallow initCause
80 }
81
82 /**
83 * Constructs a <code>ClassNotFoundException</code> with the
84 * specified detail message and optional exception that was
85 * raised while loading the class.
86 *
87 * @param s the detail message
88 * @param ex the exception that was raised while loading the class
89 * @since 1.2
90 */
91 public ClassNotFoundException(String s, Throwable ex) {
92 super(s, ex); // Disallow initCause
93 }
94
95 /**
96 * Returns the exception that was raised if an error occurred while
97 * attempting to load the class. Otherwise, returns {@code null}.
98 *
99 * <p>This method predates the general-purpose exception chaining facility.
100 * The {@link Throwable#getCause()} method is now the preferred means of
101 * obtaining this information.
102 *
103 * @return the <code>Exception</code> that was raised while loading a class
104 * @since 1.2
105 */
106 public Throwable getException() {
107 return super.getCause();
108 }
109
110 /**
111 * Serializable fields for ClassNotFoundException.
112 *
113 * @serialField ex Throwable
114 */
115 @java.io.Serial
116 private static final ObjectStreamField[] serialPersistentFields = {
117 new ObjectStreamField("ex", Throwable.class)
118 };
119
120 /*
121 * Reconstitutes the ClassNotFoundException instance from a stream
122 * and initialize the cause properly when deserializing from an older
123 * version.
124 *
125 * The getException and getCause method returns the private "ex" field
126 * in the older implementation and ClassNotFoundException::cause
127 * was set to null.
128 */
129 @java.io.Serial
130 private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException {
131 ObjectInputStream.GetField fields = s.readFields();
132 Throwable exception = (Throwable) fields.get("ex", null);
133 if (exception != null) {
134 setCause(exception);
135 }
136 }
137
138 /*
139 * To maintain compatibility with older implementation, write a serial
140 * "ex" field with the cause as the value.
141 */
142 @java.io.Serial
143 private void writeObject(ObjectOutputStream out) throws IOException {
144 ObjectOutputStream.PutField fields = out.putFields();
145 fields.put("ex", super.getCause());
146 out.writeFields();
147 }
148 }