    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
    045package org.jfree.util;
    046
    047import java.io.PrintStream;
    048import 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 */
    061public 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}