Source for org.jfree.util.StackableException

   1: /* ========================================================================
   2:  * JCommon : a free general purpose class library for the Java(tm) platform
   3:  * ========================================================================
   4:  *
   5:  * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors.
   6:  * 
   7:  * Project Info:  http://www.jfree.org/jcommon/index.html
   8:  *
   9:  * This library is free software; you can redistribute it and/or modify it 
  10:  * under the terms of the GNU Lesser General Public License as published by 
  11:  * the Free Software Foundation; either version 2.1 of the License, or 
  12:  * (at your option) any later version.
  13:  *
  14:  * This library is distributed in the hope that it will be useful, but 
  15:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
  16:  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 
  17:  * License for more details.
  18:  *
  19:  * You should have received a copy of the GNU Lesser General Public
  20:  * License along with this library; if not, write to the Free Software
  21:  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, 
  22:  * USA.  
  23:  *
  24:  * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 
  25:  * in the United States and other countries.]
  26:  * 
  27:  * -----------------------
  28:  * StackableException.java
  29:  * -----------------------
  30:  * (C)opyright 2002-2004, by Thomas Morgner and Contributors.
  31:  *
  32:  * Original Author:  Thomas Morgner;
  33:  * Contributor(s):   David Gilbert (for Object Refinery Limited);
  34:  *
  35:  * $Id: StackableException.java,v 1.3 2005/11/14 10:56:55 mungady Exp $
  36:  *
  37:  * Changes
  38:  * -------
  39:  * 06-Dec-2002 : Initial version
  40:  * 10-Dec-2002 : Fixed issues reported by Checkstyle (DG);
  41:  * 29-Apr-2003 : Distilled from the JFreeReport project and moved into JCommon
  42:  *
  43:  */
  44: 
  45: package org.jfree.util;
  46: 
  47: import java.io.PrintStream;
  48: import java.io.PrintWriter;
  49: 
  50: /**
  51:  * A baseclass for exceptions, which could have parent exceptions. These parent exceptions
  52:  * are raised in a subclass and are now wrapped into a subclass of this Exception.
  53:  * <p>
  54:  * The parents are printed when this exception is printed. This class exists mainly for
  55:  * debugging reasons, as with them it is easier to detect the root cause of an error.
  56:  *
  57:  * <!-- In a perfect world there would be no need for such a class :)-->
  58:  *
  59:  * @author Thomas Morgner
  60:  */
  61: public abstract class StackableException extends Exception {
  62: 
  63:     /** The parent exception. */
  64:     private Exception parent;
  65: 
  66:     /**
  67:      * Creates a StackableRuntimeException with no message and no parent.
  68:      */
  69:     public StackableException() {
  70:         super();
  71:     }
  72: 
  73:     /**
  74:      * Creates an exception.
  75:      *
  76:      * @param message  the exception message.
  77:      * @param ex  the parent exception.
  78:      */
  79:     public StackableException(final String message, final Exception ex) {
  80:         super(message);
  81:         this.parent = ex;
  82:     }
  83: 
  84:     /**
  85:      * Creates an exception.
  86:      *
  87:      * @param message  the exception message.
  88:      */
  89:     public StackableException(final String message) {
  90:         super(message);
  91:     }
  92: 
  93:     /**
  94:      * Returns the parent exception (possibly null).
  95:      *
  96:      * @return the parent exception.
  97:      */
  98:     public Exception getParent() {
  99:         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: }