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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  /**
29   * Thrown when an application tries to load in a class through its
30   * string name using:
31   * <ul>
32   * <li>The <code>forName</code> method in class <code>Class</code>.
33   * <li>The <code>findSystemClass</code> method in class
34   *     <code>ClassLoader</code> .
35   * <li>The <code>loadClass</code> method in class <code>ClassLoader</code>.
36   * </ul>
37   * <p>
38   * but no definition for the class with the specified name could be found.
39   *
40   * <p>As of release 1.4, this exception has been retrofitted to conform to
41   * the general purpose exception-chaining mechanism.  The "optional exception
42   * that was raised while loading the class" that may be provided at
43   * construction time and accessed via the {@link #getException()} method is
44   * now known as the <i>cause</i>, and may be accessed via the {@link
45   * Throwable#getCause()} method, as well as the aforementioned "legacy method."
46   *
47   * @author  unascribed
48   * @see     java.lang.Class#forName(java.lang.String)
49   * @see     java.lang.ClassLoader#findSystemClass(java.lang.String)
50   * @see     java.lang.ClassLoader#loadClass(java.lang.String, boolean)
51   * @since   JDK1.0
52   */
53  public class ClassNotFoundException extends ReflectiveOperationException {
54      /**
55       * use serialVersionUID from JDK 1.1.X for interoperability
56       */
57       private static final long serialVersionUID = 9176873029745254542L;
58  
59      /**
60       * This field holds the exception ex if the
61       * ClassNotFoundException(String s, Throwable ex) constructor was
62       * used to instantiate the object
63       * @serial
64       * @since 1.2
65       */
66      private Throwable ex;
67  
68      /**
69       * Constructs a <code>ClassNotFoundException</code> with no detail message.
70       */
71      public ClassNotFoundException() {
72          super((Throwable)null);  // Disallow initCause
73      }
74  
75      /**
76       * Constructs a <code>ClassNotFoundException</code> with the
77       * specified detail message.
78       *
79       * @param   s   the detail message.
80       */
81      public ClassNotFoundException(String s) {
82          super(s, null);  //  Disallow initCause
83      }
84  
85      /**
86       * Constructs a <code>ClassNotFoundException</code> with the
87       * specified detail message and optional exception that was
88       * raised while loading the class.
89       *
90       * @param s the detail message
91       * @param ex the exception that was raised while loading the class
92       * @since 1.2
93       */
94      public ClassNotFoundException(String s, Throwable ex) {
95          super(s, null);  //  Disallow initCause
96          this.ex = ex;
97      }
98  
99      /**
100      * Returns the exception that was raised if an error occurred while
101      * attempting to load the class. Otherwise, returns <tt>null</tt>.
102      *
103      * <p>This method predates the general-purpose exception chaining facility.
104      * The {@link Throwable#getCause()} method is now the preferred means of
105      * obtaining this information.
106      *
107      * @return the <code>Exception</code> that was raised while loading a class
108      * @since 1.2
109      */
110     public Throwable getException() {
111         return ex;
112     }
113 
114     /**
115      * Returns the cause of this exception (the exception that was raised
116      * if an error occurred while attempting to load the class; otherwise
117      * <tt>null</tt>).
118      *
119      * @return  the cause of this exception.
120      * @since   1.4
121      */
122     public Throwable getCause() {
123         return ex;
124     }
125 }