IllegalStateException

AI-generated Key Takeaways

• IllegalStateException signals that a method has been invoked at an illegal or inappropriate time, meaning the Java environment or application is not in the correct state for the operation.

• It's an unchecked exception, extending RuntimeException, indicating it doesn't need to be explicitly declared in a method's throws clause.

• The exception provides constructors to include a detailed message, a cause, or both, offering context for debugging.

• Numerous direct subclasses like AlreadyBoundException and ClosedSelectorException address specific illegal state scenarios within Java's core libraries.

• Developers should use IllegalStateException when a method is called unexpectedly given the current object or system state, aiding in identifying and resolving program flow issues.

public class IllegalStateException extends RuntimeException

Known Direct Subclasses AcceptPendingException, AlreadyBoundException, AlreadyConnectedException, CancellationException, CancelledKeyException, ClosedDirectoryStreamException, ClosedFileSystemException, ClosedSelectorException, ClosedWatchServiceException, ConnectionPendingException, FormatterClosedException, IllegalBlockingModeException, InvalidMarkException, NoConnectionPendingException, NonReadableChannelException, and 7 others. AcceptPendingException Unchecked exception thrown when an attempt is made to initiate an accept operation on a channel and a previous accept operation has not completed.  AlreadyBoundException Unchecked exception thrown when an attempt is made to bind the socket a network oriented channel that is already bound.  AlreadyConnectedException Unchecked exception thrown when an attempt is made to connect a SocketChannel that is already connected.  CancellationException Exception indicating that the result of a value-producing task, such as a FutureTask, cannot be retrieved because the task was cancelled.  CancelledKeyException Unchecked exception thrown when an attempt is made to use a selection key that is no longer valid.  ClosedDirectoryStreamException Unchecked exception thrown when an attempt is made to invoke an operation on a directory stream that is closed.  ClosedFileSystemException Unchecked exception thrown when an attempt is made to invoke an operation on a file and the file system is closed.  ClosedSelectorException Unchecked exception thrown when an attempt is made to invoke an I/O operation upon a closed selector.  ClosedWatchServiceException Unchecked exception thrown when an attempt is made to invoke an operation on a watch service that is closed.  ConnectionPendingException Unchecked exception thrown when an attempt is made to connect a SocketChannel for which a non-blocking connection operation is already in progress.  FormatterClosedException Unchecked exception thrown when the formatter has been closed.  IllegalBlockingModeException Unchecked exception thrown when a blocking-mode-specific operation is invoked upon a channel in the incorrect blocking mode.  InvalidMarkException Unchecked exception thrown when an attempt is made to reset a buffer when its mark is not defined.  NoConnectionPendingException Unchecked exception thrown when the finishConnect method of a SocketChannel is invoked without first successfully invoking its connect method.  NonReadableChannelException Unchecked exception thrown when an attempt is made to read from a channel that was not originally opened for reading.  NonWritableChannelException Unchecked exception thrown when an attempt is made to write to a channel that was not originally opened for writing.  NotYetBoundException Unchecked exception thrown when an attempt is made to invoke an I/O operation upon a server socket channel that is not yet bound.  NotYetConnectedException Unchecked exception thrown when an attempt is made to invoke an I/O operation upon a socket channel that is not yet connected.  OverlappingFileLockException Unchecked exception thrown when an attempt is made to acquire a lock on a region of a file that overlaps a region already locked by the same Java virtual machine, or when another thread is already waiting to lock an overlapping region of the same file.  ReadPendingException Unchecked exception thrown when an attempt is made to read from an asynchronous socket channel and a previous read has not completed.  ShutdownChannelGroupException Unchecked exception thrown when an attempt is made to construct a channel in a group that is shutdown or the completion handler for an I/O operation cannot be invoked because the channel group has terminated.  WritePendingException Unchecked exception thrown when an attempt is made to write to an asynchronous socket channel and a previous write has not completed.

Signals that a method has been invoked at an illegal or inappropriate time. In other words, the Java environment or Java application is not in an appropriate state for the requested operation.

Public Constructor Summary

	IllegalStateException() Constructs an IllegalStateException with no detail message.
	IllegalStateException(String s) Constructs an IllegalStateException with the specified detail message.
	IllegalStateException(String message, Throwable cause) Constructs a new exception with the specified detail message and cause.
	IllegalStateException(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).

Inherited Method Summary

From class java.lang.Throwable

synchronized final void	addSuppressed(Throwable exception) Appends the specified exception to the exceptions that were suppressed in order to deliver this exception.
synchronized Throwable	fillInStackTrace() Fills in the execution stack trace.
synchronized 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 printStackTrace().
synchronized 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.
synchronized 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(PrintWriter s) Prints this throwable and its backtrace to the specified print writer.
void	printStackTrace(PrintStream s) Prints this throwable and its backtrace to the specified print stream.
void	setStackTrace(StackTraceElement[] stackTrace) Sets the stack trace elements that will be returned by getStackTrace() and printed by printStackTrace() and related methods.
String	toString() Returns a short description of this throwable.

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Public Constructors

public IllegalStateException ()

Constructs an IllegalStateException with no detail message. A detail message is a String that describes this particular exception.

public IllegalStateException (String s)

Constructs an IllegalStateException with the specified detail message. A detail message is a String that describes this particular exception.

Parameters

s	the String that contains a detailed message

public IllegalStateException (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.)

public IllegalStateException (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). This constructor is useful for exceptions that are little more than wrappers for other throwables (for example, PrivilegedActionException).

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.)