Class ConcurrentModificationException

java.lang.Object

java.lang.Throwable

java.lang.Exception

java.lang.RuntimeException

java.util.ConcurrentModificationException

All Implemented Interfaces:

Serializable

Direct Known Subclasses:

DirectoryIteratorException

public class ConcurrentModificationException
extends RuntimeException

This exception may be thrown by methods that have detected concurrent modification of an object when such modification is not permissible.

For example, it is not generally permissible for one thread to modify a Collection while another thread is iterating over it. In general, the results of the iteration are undefined under these circumstances. Some Iterator implementations (including those of all the general purpose collection implementations provided by the JRE) may choose to throw this exception if this behavior is detected. Iterators that do this are known as fail-fast iterators, as they fail quickly and cleanly, rather that risking arbitrary, non-deterministic behavior at an undetermined time in the future.

Note that this exception does not always indicate that an object has been concurrently modified by a different thread. If a single thread issues a sequence of method invocations that violates the contract of an object, the object may throw this exception. For example, if a thread modifies a collection directly while it is iterating over the collection with a fail-fast iterator, the iterator will throw this exception.

Note that fail-fast behavior cannot be guaranteed as it is, generally speaking, impossible to make any hard guarantees in the presence of unsynchronized concurrent modification. Fail-fast operations throw ConcurrentModificationException on a best-effort basis. Therefore, it would be wrong to write a program that depended on this exception for its correctness: ConcurrentModificationException should be used only to detect bugs.

Since:

1.2

See Also:

• Collection
• Iterator
• Spliterator
• ListIterator
• Vector
• LinkedList
• HashSet
• Hashtable
• TreeMap
• AbstractList
• Serialized Form

Constructor Summary

Constructors

Constructor	Description
ConcurrentModificationException()	Constructs a ConcurrentModificationException with no detail message.
ConcurrentModificationException(String message)	Constructs a ConcurrentModificationException with the specified detail message.
ConcurrentModificationException(String message, Throwable cause)	Constructs a new exception with the specified detail message and cause.
ConcurrentModificationException(Throwable cause)	Constructs a new exception with the specified cause and a detail message of (cause==null ? null : cause.toString()) (which typically contains the class and detail message of cause.

Method Summary

Methods declared in class Throwable

addSuppressed, fillInStackTrace, getCause, getLocalizedMessage, getMessage, getStackTrace, getSuppressed, initCause, printStackTrace, printStackTrace, printStackTrace, setStackTrace, toString

Modifier and Type	Method	Description
final void	addSuppressed(Throwable exception)	Appends the specified exception to the exceptions that were suppressed in order to deliver this exception.
Throwable	fillInStackTrace()	Fills in the execution stack trace.
Throwable	getCause()	Returns the cause of this throwable or null if the cause is nonexistent or unknown.
String	getLocalizedMessage()	Creates a localized description of this throwable.
String	getMessage()	Returns the detail message string of this throwable.
StackTraceElement[]	getStackTrace()	Provides programmatic access to the stack trace information printed by Throwable.printStackTrace().
final Throwable[]	getSuppressed()	Returns an array containing all of the exceptions that were suppressed, typically by the try-with-resources statement, in order to deliver this exception.
Throwable	initCause(Throwable cause)	Initializes the cause of this throwable to the specified value.
void	printStackTrace()	Prints this throwable and its backtrace to the standard error stream.
void	printStackTrace(PrintStream s)	Prints this throwable and its backtrace to the specified print stream.
void	printStackTrace(PrintWriter s)	Prints this throwable and its backtrace to the specified print writer.
void	setStackTrace(StackTraceElement[] stackTrace)	Sets the stack trace elements that will be returned by Throwable.getStackTrace() and printed by Throwable.printStackTrace() and related methods.
String	toString()	Returns a short description of this throwable.

Methods declared in class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Modifier and Type	Method	Description
protected Object	clone()	Creates and returns a copy of this object.
boolean	equals(Object obj)	Indicates whether some other object is "equal to" this one.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
final Class<?>	getClass()	Returns the runtime class of this Object.
int	hashCode()	Returns a hash code value for this object.
final void	notify()	Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll()	Wakes up all threads that are waiting on this object's monitor.
final void	wait()	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
final void	wait(long timeoutMillis)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
final void	wait(long timeoutMillis, int nanos)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Constructor Details

ConcurrentModificationException

public ConcurrentModificationException()

Constructs a ConcurrentModificationException with no detail message.

ConcurrentModificationException

public ConcurrentModificationException(String message)

Constructs a ConcurrentModificationException with the specified detail message.

Parameters:

message - the detail message pertaining to this exception.

ConcurrentModificationException

public ConcurrentModificationException(Throwable cause)

Constructs a new exception with the specified cause and a detail message of (cause==null ? null : cause.toString()) (which typically contains the class and detail message of cause.

Parameters:

cause - the cause (which is saved for later retrieval by the Throwable.getCause() method). (A null value is permitted, and indicates that the cause is nonexistent or unknown.)

Since:

1.7

ConcurrentModificationException

public ConcurrentModificationException(String message,
 Throwable cause)

Constructs a new exception with the specified detail message and cause.

Note that the detail message associated with cause is not automatically incorporated in this exception's detail message.

Parameters:

message - the detail message (which is saved for later retrieval by the Throwable.getMessage() method).

cause - the cause (which is saved for later retrieval by the Throwable.getCause() method). (A null value is permitted, and indicates that the cause is nonexistent or unknown.)

Since:

1.7