KickJava   Java API By Example, From Geeks To Geeks.

Java > Open Source Codes > net > sf > clirr > core > internal > ExceptionUtil


1 //////////////////////////////////////////////////////////////////////////////
2 // Clirr: compares two versions of a java library for binary compatibility
3 // Copyright (C) 2003 - 2005 Lars Kühne
4 //
5 // This library is free software; you can redistribute it and/or
6 // modify it under the terms of the GNU Lesser General Public
7 // License as published by the Free Software Foundation; either
8 // version 2.1 of the License, or (at your option) any later version.
9 //
10 // This library is distributed in the hope that it will be useful,
11 // but WITHOUT ANY WARRANTY; without even the implied warranty of
12 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 // Lesser General Public License for more details.
14 //
15 // You should have received a copy of the GNU Lesser General Public
16 // License along with this library; if not, write to the Free Software
17 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 //////////////////////////////////////////////////////////////////////////////
19
20 package net.sf.clirr.core.internal;
21
22 import java.lang.reflect.Method JavaDoc;
23
24 /**
25  * A helper class to initialize the cause of an exception.
26  *
27  * This allows Clirr to be compile time compatible with JDK 1.3
28  * at still taking advantage of the JDK 1.4 chained exceptions feature
29  * if available.
30  *
31  * @author lkuehne
32  */
33 public final class ExceptionUtil
34 {
35     /** Disallow instantiation. */
36     private ExceptionUtil()
37     {
38     }
39
40     private static Method JavaDoc initCauseMethod;
41
42     static
43     {
44         try
45         {
46             initCauseMethod = Throwable JavaDoc.class.getMethod("initCause", new Class JavaDoc[]{Throwable JavaDoc.class});
47         }
48         catch (NoSuchMethodException JavaDoc e)
49         {
50             // we're on JDK < 1.4, no cause data will be available in Exception stacktraces
51 initCauseMethod = null;
52         }
53     }
54
55     /**
56      * Initializes the chained exception if possible.
57      * Does nothing if chained exceptions are not available on the
58      * current JDK (1.3 or lower).
59      *
60      * @param t the resulting exception (high abstraction level)
61      * @param cause the underlying cause of t (low abstraction level)
62      */
63     public static void initCause(Throwable JavaDoc t, Throwable JavaDoc cause)
64     {
65         if (initCauseMethod == null)
66         {
67             return;
68         }
69
70         try
71         {
72             initCauseMethod.invoke(t, new Throwable JavaDoc[]{cause});
73         }
74         catch (Exception JavaDoc e)
75         {
76             if (e instanceof RuntimeException JavaDoc)
77             {
78                 throw (RuntimeException JavaDoc) e;
79             }
80             throw new RuntimeException JavaDoc("unable to initCause: " + e.toString());
81         }
82     }
83 }
84
Popular Tags