/*
 * Copyright (c) 1996, 2004, Oracle and/or its affiliates. All rights reserved.
 * 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.reflect;

import jdk.internal.misc.SharedSecrets;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamField;

/**
 * InvocationTargetException is a checked exception that wraps
 * an exception thrown by an invoked method or constructor.
 *
 * <p>As of release 1.4, this exception has been retrofitted to conform to
 * the general purpose exception-chaining mechanism.  The "target exception"
 * that is provided at construction time and accessed via the
 * {@link #getTargetException()} 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."
 *
 * @see Method
 * @see Constructor
 * @since 1.1
 */
public class InvocationTargetException extends ReflectiveOperationException {
    /**
     * Use serialVersionUID from JDK 1.1.X for interoperability
     */
    private static final long serialVersionUID = 4085088731926701167L;

    /**
     * Constructs an {@code InvocationTargetException} with
     * {@code null} as the target exception.
     */
    protected InvocationTargetException() {
        super((Throwable)null);  // Disallow initCause
    }

    /**
     * Constructs a InvocationTargetException with a target exception.
     *
     * @param target the target exception
     */
    public InvocationTargetException(Throwable target) {
        super(null, target);  // Disallow initCause
    }

    /**
     * Constructs a InvocationTargetException with a target exception
     * and a detail message.
     *
     * @param target the target exception
     * @param s      the detail message
     */
    public InvocationTargetException(Throwable target, String s) {
        super(s, target);  // Disallow initCause
    }

    /**
     * Get the thrown target exception.
     *
     * <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 thrown target exception (cause of this exception).
     */
    public Throwable getTargetException() {
        return super.getCause();
    }

    /**
     * Serializable fields for UndeclaredThrowableException.
     *
     * @serialField target Throwable
     */
    private static final ObjectStreamField[] serialPersistentFields = {
        new ObjectStreamField("target", Throwable.class)
    };

    /*
     * Reconstitutes the InvocationTargetException instance from a stream
     * and initialize the cause properly when deserializing from an older
     * version.
     *
     * The getException and getCause method returns the private "target" field
     * in the older implementation and InvocationTargetException::cause
     * was set to null.
     */
    private void readObject(ObjectInputStream s) throws IOException, ClassNotFoundException {
        ObjectInputStream.GetField fields = s.readFields();
        Throwable exception = (Throwable) fields.get("target", null);
        if (exception != null) {
            SharedSecrets.getJavaLangAccess().setCause(this, exception);
        }
    }

    /*
     * To maintain compatibility with older implementation, write a serial
     * "target" field with the cause as the value.
     */
    private void writeObject(ObjectOutputStream out) throws IOException {
        ObjectOutputStream.PutField fields = out.putFields();
        fields.put("target", super.getCause());
        out.writeFields();
    }
}