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29 * This exception may be thrown by methods that have detected concurrent
30 * modification of an object when such modification is not permissible.
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.
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.
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>
69 public class ConcurrentModificationException extends RuntimeException {
70 private static final long serialVersionUID = -3666751008965953603L;
73 * Constructs a ConcurrentModificationException with no
76 public ConcurrentModificationException() {
80 * Constructs a {@code ConcurrentModificationException} with the
81 * specified detail message.
83 * @param message the detail message pertaining to this exception.
85 public ConcurrentModificationException(String message) {
90 * Constructs a new exception with the specified cause and a detail
91 * message of {@code (cause==null ? null : cause.toString())} (which
92 * typically contains the class and detail message of {@code cause}.
94 * @param cause the cause (which is saved for later retrieval by the
95 * {@link Throwable#getCause()} method). (A {@code null} value is
96 * permitted, and indicates that the cause is nonexistent or
100 public ConcurrentModificationException(Throwable cause) {
105 * Constructs a new exception with the specified detail message and
108 * <p>Note that the detail message associated with <code>cause</code> is
109 * <i>not</i> automatically incorporated in this exception's detail
112 * @param message the detail message (which is saved for later retrieval
113 * by the {@link Throwable#getMessage()} method).
114 * @param cause the cause (which is saved for later retrieval by the
115 * {@link Throwable#getCause()} method). (A {@code null} value
116 * is permitted, and indicates that the cause is nonexistent or
120 public ConcurrentModificationException(String message, Throwable cause) {
121 super(message, cause);