01: /* $Id: PluginAssertionFailure.java 476205 2006-11-17 16:43:10Z dennisl $
02: *
03: * Licensed to the Apache Software Foundation (ASF) under one or more
04: * contributor license agreements. See the NOTICE file distributed with
05: * this work for additional information regarding copyright ownership.
06: * The ASF licenses this file to You under the Apache License, Version 2.0
07: * (the "License"); you may not use this file except in compliance with
08: * the License. You may obtain a copy of the License at
09: *
10: * http://www.apache.org/licenses/LICENSE-2.0
11: *
12: * Unless required by applicable law or agreed to in writing, software
13: * distributed under the License is distributed on an "AS IS" BASIS,
14: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15: * See the License for the specific language governing permissions and
16: * limitations under the License.
17: */
18:
19: package org.apache.commons.digester.plugins;
20:
21: /**
22: * Thrown when a bug is detected in the plugins code.
23: * <p>
24: * This class is intended to be used in assertion statements, similar to
25: * the way that java 1.4's native assertion mechanism is used. However there
26: * is a difference: when a java 1.4 assertion fails, an AssertionError
27: * is thrown, which is a subclass of Error; here, the PluginAssertionFailure
28: * class extends RuntimeException rather than Error.
29: * <p>
30: * This difference in design is because throwing Error objects is not
31: * good in a container-based architecture.
32: * <p>
33: * Example:
34: * <pre>
35: * if (impossibleCondition) {
36: * throw new PluginAssertionFailure(
37: * "internal error: impossible condition is true");
38: * }
39: * </pre>
40: * <p>
41: * Note that PluginAssertionFailure should <i>not</i> be thrown when user
42: * input is bad, or when code external to the Digester module passes invalid
43: * parameters to a plugins method. It should be used only in checks for
44: * problems which indicate internal bugs within the plugins module.
45: *
46: * @since 1.6
47: */
48: public class PluginAssertionFailure extends RuntimeException {
49:
50: private Throwable cause = null;
51:
52: /**
53: * @param cause underlying exception that caused this to be thrown
54: */
55: public PluginAssertionFailure(Throwable cause) {
56: this (cause.getMessage());
57: this .cause = cause;
58: }
59:
60: /**
61: * @param msg describes the reason this exception is being thrown.
62: */
63: public PluginAssertionFailure(String msg) {
64: super (msg);
65: }
66:
67: /**
68: * @param msg describes the reason this exception is being thrown.
69: * @param cause underlying exception that caused this to be thrown
70: */
71: public PluginAssertionFailure(String msg, Throwable cause) {
72: this (msg);
73: this .cause = cause;
74: }
75:
76: /**
77: * Return the cause of this exception (if any) as specified in the
78: * exception constructor.
79: *
80: * @since 1.8
81: */
82: public Throwable getCause() {
83: return cause;
84: }
85: }
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