    001    /* ========================================================================
    002     * JCommon : a free general purpose class library for the Java(tm) platform
    003     * ========================================================================
    004     *
    005     * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
    006     *
    007     * Project Info:  http://www.jfree.org/jcommon/index.html
    008     *
    009     * This library is free software; you can redistribute it and/or modify it
    010     * under the terms of the GNU Lesser General Public License as published by
    011     * the Free Software Foundation; either version 2.1 of the License, or
    012     * (at your option) any later version.
    013     *
    014     * This library is distributed in the hope that it will be useful, but
    015     * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    016     * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
    017     * License for more details.
    018     *
    019     * You should have received a copy of the GNU Lesser General Public
    020     * License along with this library; if not, write to the Free Software
    021     * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
    022     * USA.
    023     *
    024     * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
    025     * in the United States and other countries.]
    026     *
    027     * -----------------------
    028     * StackableException.java
    029     * -----------------------
    030     * (C)opyright 2002-2004, by Thomas Morgner and Contributors.
    031     *
    032     * Original Author:  Thomas Morgner;
    033     * Contributor(s):   David Gilbert (for Object Refinery Limited);
    034     *
    035     * $Id: StackableException.java,v 1.3 2005/11/14 10:56:55 mungady Exp $
    036     *
    037     * Changes
    038     * -------
    039     * 06-Dec-2002 : Initial version
    040     * 10-Dec-2002 : Fixed issues reported by Checkstyle (DG);
    041     * 29-Apr-2003 : Distilled from the JFreeReport project and moved into JCommon
    042     *
    043     */
    044
    045    package org.jfree.util;
    046
    047    import java.io.PrintStream;
    048    import java.io.PrintWriter;
    049
    050    /**
    051     * A baseclass for exceptions, which could have parent exceptions. These parent exceptions
    052     * are raised in a subclass and are now wrapped into a subclass of this Exception.
    053     * <p>
    054     * The parents are printed when this exception is printed. This class exists mainly for
    055     * debugging reasons, as with them it is easier to detect the root cause of an error.
    056     *
    057     * <!-- In a perfect world there would be no need for such a class :)-->
    058     *
    059     * @author Thomas Morgner
    060     */
    061    public abstract class StackableException extends Exception {
    062
    063        /** The parent exception. */
    064        private Exception parent;
    065
    066        /**
    067         * Creates a StackableRuntimeException with no message and no parent.
    068         */
    069        public StackableException() {
    070            super();
    071        }
    072
    073        /**
    074         * Creates an exception.
    075         *
    076         * @param message  the exception message.
    077         * @param ex  the parent exception.
    078         */
    079        public StackableException(final String message, final Exception ex) {
    080            super(message);
    081            this.parent = ex;
    082        }
    083
    084        /**
    085         * Creates an exception.
    086         *
    087         * @param message  the exception message.
    088         */
    089        public StackableException(final String message) {
    090            super(message);
    091        }
    092
    093        /**
    094         * Returns the parent exception (possibly null).
    095         *
    096         * @return the parent exception.
    097         */
    098        public Exception getParent() {
    099            return this.parent;
    100        }
    101
    102        /**
    103         * Prints the stack trace to the specified stream.
    104         *
    105         * @param stream  the output stream.
    106         */
    107        public void printStackTrace(final PrintStream stream) {
    108            super.printStackTrace(stream);
    109            if (getParent() != null) {
    110                stream.println("ParentException: ");
    111                getParent().printStackTrace(stream);
    112            }
    113        }
    114
    115        /**
    116         * Prints the stack trace to the specified writer.
    117         *
    118         * @param writer  the writer.
    119         */
    120        public void printStackTrace(final PrintWriter writer) {
    121            super.printStackTrace(writer);
    122            if (getParent() != null) {
    123                writer.println("ParentException: ");
    124                getParent().printStackTrace(writer);
    125            }
    126        }
    127
    128        /**
    129         * Prints this <code>Throwable</code> and its backtrace to the
    130         * standard error stream. This method prints a stack trace for this
    131         * <code>Throwable</code> object on the error output stream that is
    132         * the value of the field <code>System.err</code>. The first line of
    133         * output contains the result of the {@link #toString()} method for
    134         * this object. Remaining lines represent data previously recorded by
    135         * the method {@link #fillInStackTrace()}. The format of this
    136         * information depends on the implementation, but the following
    137         * example may be regarded as typical:
    138         * <blockquote><pre>
    139         * java.lang.NullPointerException
    140         *         at MyClass.mash(MyClass.java:9)
    141         *         at MyClass.crunch(MyClass.java:6)
    142         *         at MyClass.main(MyClass.java:3)
    143         * </pre></blockquote>
    144         * This example was produced by running the program:
    145         * <blockquote><pre>
    146         *
    147         * class MyClass {
    148         *
    149         *     public static void main(String[] argv) {
    150         *         crunch(null);
    151         *     }
    152         *     static void crunch(int[] a) {
    153         *         mash(a);
    154         *     }
    155         *
    156         *     static void mash(int[] b) {
    157         *         System.out.println(b[0]);
    158         *     }
    159         * }
    160         * </pre></blockquote>
    161         *
    162         * @see     System#err
    163         */
    164        public void printStackTrace() {
    165            synchronized (System.err) {
    166                printStackTrace(System.err);
    167            }
    168        }
    169    }