/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package java.lang;

import java.io.IOException;

import java.io.ObjectInputStream;

import java.io.ObjectOutputStream;

import java.io.ObjectStreamField;

/**

 * Thrown when an application tries to load in a class through its

 * string name using:

 * <ul>

 * <li>The <code>forName</code> method in class <code>Class</code>.

 * <li>The <code>findSystemClass</code> method in class

 *     <code>ClassLoader</code> .

 * <li>The <code>loadClass</code> method in class <code>ClassLoader</code>.

 * </ul>

 * <p>

 * but no definition for the class with the specified name could be found.

 *

 * <p>As of release 1.4, this exception has been retrofitted to conform to

 * the general purpose exception-chaining mechanism.  The "optional exception

 * that was raised while loading the class" that may be provided at

 * construction time and accessed via the {@link #getException()} method is

 * now known as the <i>cause</i>, and may be accessed via the {@link

 * Throwable#getCause()} method, as well as the aforementioned "legacy method."

 *

 * @author  unascribed

 * @see     java.lang.Class#forName(java.lang.String)

 * @see     java.lang.ClassLoader#findSystemClass(java.lang.String)

 * @see     java.lang.ClassLoader#loadClass(java.lang.String, boolean)

 * @since   1.0

 */

public class ClassNotFoundException extends ReflectiveOperationException {

    /**

     * use serialVersionUID from JDK 1.1.X for interoperability

     */

     private static final long serialVersionUID = 9176873029745254542L;

    /**

     * Constructs a <code>ClassNotFoundException</code> with no detail message.

     */

    public ClassNotFoundException() {

        super((Throwable)null);  // Disallow initCause

    }

    /**

     * Constructs a <code>ClassNotFoundException</code> with the

     * specified detail message.

     *

     * @param   s   the detail message.

     */

    public ClassNotFoundException(String s) {

        super(s, null);  //  Disallow initCause

    }

    /**

     * Constructs a <code>ClassNotFoundException</code> with the

     * specified detail message and optional exception that was

     * raised while loading the class.

     *

     * @param s the detail message

     * @param ex the exception that was raised while loading the class

     * @since 1.2

     */

    public ClassNotFoundException(String s, Throwable ex) {

        super(s, ex);  //  Disallow initCause

    }

    /**

     * Returns the exception that was raised if an error occurred while

     * attempting to load the class. Otherwise, returns {@code null}.

     *

     * <p>This method predates the general-purpose exception chaining facility.

     * The {@link Throwable#getCause()} method is now the preferred means of

     * obtaining this information.

     *

     * @return the <code>Exception</code> that was raised while loading a class

     * @since 1.2

     */

    public Throwable getException() {

        return super.getCause();

    }

    /**

     * Serializable fields for ClassNotFoundException.

     *

     * @serialField ex Throwable

     */

    private static final ObjectStreamField[] serialPersistentFields = {

        new ObjectStreamField("ex", Throwable.class)

    };

    /*

     * Reconstitutes the ClassNotFoundException instance from a stream

     * and initialize the cause properly when deserializing from an older

     * version.

     *

     * The getException and getCause method returns the private "ex" field

     * in the older implementation and ClassNotFoundException::cause

     * was set to null.

     */

    private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException {

        ObjectInputStream.GetField fields = s.readFields();

        Throwable exception = (Throwable) fields.get("ex", null);

        if (exception != null) {

            setCause(exception);

        }

    }

    /*

     * To maintain compatibility with older implementation, write a serial

     * "ex" field with the cause as the value.

     */

    private void writeObject(ObjectOutputStream out) throws IOException {

        ObjectOutputStream.PutField fields = out.putFields();

        fields.put("ex", super.getCause());

        out.writeFields();

    }

}