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   1.0
  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      * Constructs a <code>ClassNotFoundException</code> with the
 101      * specified detail message, optional exception that was
 102      * raised while loading the class and a writableStackTrace flag.
 103      *
 104      * @param s the detail message
 105      * @param ex the exception that was raised while loading the class
 106      * @param writableStackTrace whether or not the stack trace should
 107      *                           be writable and filled-in
 108      */
 109     ClassNotFoundException(String s, Throwable ex, boolean writableStackTrace) {
 110         super(s, null, true, writableStackTrace);
 111         this.ex = ex;
 112     }
 113 
 114     /**
 115      * Returns the exception that was raised if an error occurred while
 116      * attempting to load the class. Otherwise, returns <tt>null</tt>.
 117      *
 118      * <p>This method predates the general-purpose exception chaining facility.
 119      * The {@link Throwable#getCause()} method is now the preferred means of
 120      * obtaining this information.
 121      *
 122      * @return the <code>Exception</code> that was raised while loading a class
 123      * @since 1.2
 124      */
 125     public Throwable getException() {
 126         return ex;
 127     }
 128 
 129     /**
 130      * Returns the cause of this exception (the exception that was raised
 131      * if an error occurred while attempting to load the class; otherwise
 132      * <tt>null</tt>).
 133      *
 134      * @return  the cause of this exception.
 135      * @since   1.4
 136      */
 137     public Throwable getCause() {
 138         return ex;
 139     }
 140 }