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 }