1 /* 2 * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.util; 27 28 /** 29 * This exception may be thrown by methods that have detected concurrent 30 * modification of an object when such modification is not permissible. 31 * <p> 32 * For example, it is not generally permissible for one thread to modify a Collection 33 * while another thread is iterating over it. In general, the results of the 34 * iteration are undefined under these circumstances. Some Iterator 35 * implementations (including those of all the general purpose collection implementations 36 * provided by the JRE) may choose to throw this exception if this behavior is 37 * detected. Iterators that do this are known as <i>fail-fast</i> iterators, 38 * as they fail quickly and cleanly, rather that risking arbitrary, 39 * non-deterministic behavior at an undetermined time in the future. 40 * <p> 41 * Note that this exception does not always indicate that an object has 42 * been concurrently modified by a <i>different</i> thread. If a single 43 * thread issues a sequence of method invocations that violates the 44 * contract of an object, the object may throw this exception. For 45 * example, if a thread modifies a collection directly while it is 46 * iterating over the collection with a fail-fast iterator, the iterator 47 * will throw this exception. 48 * 49 * <p>Note that fail-fast behavior cannot be guaranteed as it is, generally 50 * speaking, impossible to make any hard guarantees in the presence of 51 * unsynchronized concurrent modification. Fail-fast operations 52 * throw {@code ConcurrentModificationException} on a best-effort basis. 53 * Therefore, it would be wrong to write a program that depended on this 54 * exception for its correctness: <i>{@code ConcurrentModificationException} 55 * should be used only to detect bugs.</i> 56 * 57 * @author Josh Bloch 58 * @see Collection 59 * @see Iterator 60 * @see Spliterator 61 * @see ListIterator 62 * @see Vector 63 * @see LinkedList 64 * @see HashSet 65 * @see Hashtable 66 * @see TreeMap 67 * @see AbstractList 68 * @since 1.2 69 */ 70 public class ConcurrentModificationException extends RuntimeException { 71 private static final long serialVersionUID = -3666751008965953603L; 72 73 /** 74 * Constructs a ConcurrentModificationException with no 75 * detail message. 76 */ 77 public ConcurrentModificationException() { 78 } 79 80 /** 81 * Constructs a {@code ConcurrentModificationException} 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 90 /** 91 * Constructs a new exception with the specified cause and a detail 92 * message of {@code (cause==null ? null : cause.toString())} (which 93 * typically contains the class and detail message of {@code cause}. 94 * 95 * @param cause the cause (which is saved for later retrieval by the 96 * {@link Throwable#getCause()} method). (A {@code null} value is 97 * permitted, and indicates that the cause is nonexistent or 98 * unknown.) 99 * @since 1.7 100 */ 101 public ConcurrentModificationException(Throwable cause) { 102 super(cause); 103 } 104 105 /** 106 * Constructs a new exception with the specified detail message and 107 * cause. 108 * 109 * <p>Note that the detail message associated with <code>cause</code> is 110 * <i>not</i> automatically incorporated in this exception's detail 111 * message. 112 * 113 * @param message the detail message (which is saved for later retrieval 114 * by the {@link Throwable#getMessage()} method). 115 * @param cause the cause (which is saved for later retrieval by the 116 * {@link Throwable#getCause()} method). (A {@code null} value 117 * is permitted, and indicates that the cause is nonexistent or 118 * unknown.) 119 * @since 1.7 120 */ 121 public ConcurrentModificationException(String message, Throwable cause) { 122 super(message, cause); 123 } 124 } 125
