01: /*
02: * @(#)ConcurrentModificationException.java 1.18 06/10/10
03: *
04: * Copyright 1990-2006 Sun Microsystems, Inc. All Rights Reserved.
05: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
06: *
07: * This program is free software; you can redistribute it and/or
08: * modify it under the terms of the GNU General Public License version
09: * 2 only, as published by the Free Software Foundation.
10: *
11: * This program is distributed in the hope that it will be useful, but
12: * WITHOUT ANY WARRANTY; without even the implied warranty of
13: * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14: * General Public License version 2 for more details (a copy is
15: * included at /legal/license.txt).
16: *
17: * You should have received a copy of the GNU General Public License
18: * version 2 along with this work; if not, write to the Free Software
19: * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20: * 02110-1301 USA
21: *
22: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa
23: * Clara, CA 95054 or visit www.sun.com if you need additional
24: * information or have any questions.
25: *
26: */
27:
28: package java.util;
29:
30: /**
31: * This exception may be thrown by methods that have detected concurrent
32: * modification of an object when such modification is not permissible.
33: * <p>
34: * For example, it is not generally permssible for one thread to modify a Collection
35: * while another thread is iterating over it. In general, the results of the
36: * iteration are undefined under these circumstances. Some Iterator
37: * implementations (including those of all the collection implementations
38: * provided by the JRE) may choose to throw this exception if this behavior is
39: * detected. Iterators that do this are known as <i>fail-fast</i> iterators,
40: * as they fail quickly and cleanly, rather that risking arbitrary,
41: * non-deterministic behavior at an undetermined time in the future.
42: * <p>
43: * Note that this exception does not always indicate that an object has
44: * been concurrently modified by a <i>different</i> thread. If a single
45: * thread issues a sequence of method invocations that violates the
46: * contract of an object, the object may throw this exception. For
47: * example, if a thread modifies a collection directly while it is
48: * iterating over the collection with a fail-fast iterator, the iterator
49: * will thow this exception.
50: *
51: * <p>Note that fail-fast behavior cannot be guaranteed as it is, generally
52: * speaking, impossible to make any hard guarantees in the presence of
53: * unsynchronized concurrent modification. Fail-fast operations
54: * throw <tt>ConcurrentModificationException</tt> on a best-effort basis.
55: * Therefore, it would be wrong to write a program that depended on this
56: * exception for its correctness: <i><tt>ConcurrentModificationException</tt>
57: * should be used only to detect bugs.</i>
58: *
59: * @author Josh Bloch
60: * @version 1.11, 02/02/00
61: * @see Collection
62: * @see Iterator
63: * @see ListIterator
64: * @see Vector
65: * @see LinkedList
66: * @see HashSet
67: * @see Hashtable
68: * @see TreeMap
69: * @see AbstractList
70: * @since 1.2
71: */
72: public class ConcurrentModificationException extends RuntimeException {
73: /**
74: * Constructs a ConcurrentModificationException with no
75: * detail message.
76: */
77: public ConcurrentModificationException() {
78: }
79:
80: /**
81: * Constructs a <tt>ConcurrentModificationException</tt> with the
82: * specified detail message.
83: *
84: * @param message the detail message pertaining to this exception.
85: */
86: public ConcurrentModificationException(String message) {
87: super(message);
88: }
89: }
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