java.lang
Class ThreadGroup

java.lang.Object
  |
  +--java.lang.ThreadGroup

public class ThreadGroup

extends Object

A thread group represents a set of threads. In addition, a thread group can also include other thread groups. The thread groups form a tree in which every thread group except the initial thread group has a parent.

A thread is allowed to access information about its own thread group, but not to access information about its thread group's parent thread group or any other thread groups.

Since:

JDK1.0

Constructor Summary

ThreadGroup
copy-> new ThreadGroup( )
copy-> <ThreadGroup var> = new ThreadGroup(<String name>);

Constructs a new thread group. The parent of this new group is the thread group of the currently running thread.

The checkAccess method of the parent thread group is called with no arguments; this may result in a security exception.

Parameters:

name - the name of the new thread group.

Throws:

SecurityException - if the current thread cannot create a thread in the specified thread group.

Since:

JDK1.0

See Also:

checkAccess()

ThreadGroup
copy-> new ThreadGroup(, )
copy-> <ThreadGroup var> = new ThreadGroup(<ThreadGroup parent>, <String name>);

Creates a new thread group. The parent of this new group is the specified thread group.

The checkAccess method of the parent thread group is called with no arguments; this may result in a security exception.

Parameters:

parent - the parent thread group.

name - the name of the new thread group.

Throws:

NullPointerException - if the thread group argument is null.

SecurityException - if the current thread cannot create a thread in the specified thread group.

Since:

JDK1.0

See Also:

SecurityException, checkAccess()

Method Summary

int	activeCount() copy-> .activeCount() copy-> <int var>=<ThreadGroup>.activeCount(); Returns an estimate of the number of active threads in this thread group. Returns: the number of active threads in this thread group and in any other thread group that has this thread group as an ancestor. Since: JDK1.0
int	activeGroupCount() copy-> .activeGroupCount() copy-> <int var>=<ThreadGroup>.activeGroupCount(); Returns an estimate of the number of active groups in this thread group. Returns: the number of active thread groups with this thread group as an ancestor. Since: JDK1.0
boolean	allowThreadSuspension(boolean b) copy-> .allowThreadSuspension( ) copy-> <boolean var>=<ThreadGroup>.allowThreadSuspension(<boolean b>); Deprecated. The definition of this call depends on suspend(), which is deprecated. Further, the behavior of this call was never specified. Used by VM to control lowmem implicit suspension. Parameters: b - boolean to allow or disallow suspension Returns: true on success Since: JDK1.1
void	checkAccess() copy-> .checkAccess() copy-> <ThreadGroup>.checkAccess(); Determines if the currently running thread has permission to modify this thread group. If there is a security manager, its checkAccess method is called with this thread group as its argument. This may result in throwing a SecurityException. Throws: SecurityException - if the current thread is not allowed to access this thread group. Since: JDK1.0 See Also: SecurityManager.checkAccess(java.lang.ThreadGroup)
void	destroy() copy-> .destroy() copy-> <ThreadGroup>.destroy(); Destroys this thread group and all of its subgroups. This thread group must be empty, indicating that all threads that had been in this thread group have since stopped. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. Throws: IllegalThreadStateException - if the thread group is not empty or if the thread group has already been destroyed. SecurityException - if the current thread cannot modify this thread group. Since: JDK1.0 See Also: checkAccess()
int	enumerate(Thread[] list) copy-> .enumerate( ) copy-> <int var>=<ThreadGroup>.enumerate(<Thread[] list>); Copies into the specified array every active thread in this thread group and its subgroups. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. An application should use the activeCount method to get an estimate of how big the array should be. If the array is too short to hold all the threads, the extra threads are silently ignored. Parameters: list - an array into which to place the list of threads. Returns: the number of threads put into the array. Throws: SecurityException - if the current thread does not have permission to enumerate this thread group. Since: JDK1.0 See Also: activeCount(), checkAccess()
int	enumerate(Thread[] list, boolean recurse) copy-> .enumerate(, ) copy-> <int var>=<ThreadGroup>.enumerate(<Thread[] list>, <boolean recurse>); Copies into the specified array every active thread in this thread group. If the recurse flag is true, references to every active thread in this thread's subgroups are also included. If the array is too short to hold all the threads, the extra threads are silently ignored. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. An application should use the activeCount method to get an estimate of how big the array should be. Parameters: list - an array into which to place the list of threads. recurse - a flag indicating whether also to include threads in thread groups that are subgroups of this thread group. Returns: the number of threads placed into the array. Throws: SecurityException - if the current thread does not have permission to enumerate this thread group. Since: JDK1.0 See Also: activeCount(), checkAccess()
int	enumerate(ThreadGroup[] list) copy-> .enumerate( ) copy-> <int var>=<ThreadGroup>.enumerate(<ThreadGroup[] list>); Copies into the specified array references to every active subgroup in this thread group. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. An application should use the activeGroupCount method to get an estimate of how big the array should be. If the array is too short to hold all the thread groups, the extra thread groups are silently ignored. Parameters: list - an array into which to place the list of thread groups. Returns: the number of thread groups put into the array. Throws: SecurityException - if the current thread does not have permission to enumerate this thread group. Since: JDK1.0 See Also: activeGroupCount(), checkAccess()
int	enumerate(ThreadGroup[] list, boolean recurse) copy-> .enumerate(, ) copy-> <int var>=<ThreadGroup>.enumerate(<ThreadGroup[] list>, <boolean recurse>); Copies into the specified array references to every active subgroup in this thread group. If the recurse flag is true, references to all active subgroups of the subgroups and so forth are also included. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. An application should use the activeGroupCount method to get an estimate of how big the array should be. Parameters: list - an array into which to place the list of threads. recurse - a flag indicating whether to recursively enumerate all included thread groups. Returns: the number of thread groups put into the array. Throws: SecurityException - if the current thread does not have permission to enumerate this thread group. Since: JDK1.0 See Also: activeGroupCount(), checkAccess()
int	getMaxPriority() copy-> .getMaxPriority() copy-> <int var>=<ThreadGroup>.getMaxPriority(); Returns the maximum priority of this thread group. Threads that are part of this group cannot have a higher priority than the maximum priority. Returns: the maximum priority that a thread in this thread group can have. Since: JDK1.0 See Also: setMaxPriority(int)
String	getName() copy-> .getName() copy-> <String var>=<ThreadGroup>.getName(); Returns the name of this thread group. Returns: the name of this thread group. Since: JDK1.0
ThreadGroup	getParent() copy-> .getParent() copy-> <ThreadGroup var>=<ThreadGroup>.getParent(); Returns the parent of this thread group. First, if the parent is not null, the checkAccess method of the parent thread group is called with no arguments; this may result in a security exception. Returns: the parent of this thread group. The top-level thread group is the only thread group whose parent is null. Throws: SecurityException - if the current thread cannot modify this thread group. Since: JDK1.0 See Also: checkAccess(), SecurityException, RuntimePermission
void	interrupt() copy-> .interrupt() copy-> <ThreadGroup>.interrupt(); Interrupts all threads in this thread group. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. This method then calls the interrupt method on all the threads in this thread group and in all of its subgroups. Throws: SecurityException - if the current thread is not allowed to access this thread group or any of the threads in the thread group. Since: 1.2 See Also: Thread.interrupt(), SecurityException, checkAccess()
boolean	isDaemon() copy-> .isDaemon() copy-> <boolean var>=<ThreadGroup>.isDaemon(); Tests if this thread group is a daemon thread group. A daemon thread group is automatically destroyed when its last thread is stopped or its last thread group is destroyed. Returns: true if this thread group is a daemon thread group; false otherwise. Since: JDK1.0
boolean	isDestroyed() copy-> .isDestroyed() copy-> <boolean var>=<ThreadGroup>.isDestroyed(); Tests if this thread group has been destroyed. Returns: true if this object is destroyed Since: JDK1.1
void	list() copy-> .list() copy-> <ThreadGroup>.list(); Prints information about this thread group to the standard output. This method is useful only for debugging. Since: JDK1.0
boolean	parentOf(ThreadGroup g) copy-> .parentOf( ) copy-> <boolean var>=<ThreadGroup>.parentOf(<ThreadGroup g>); Tests if this thread group is either the thread group argument or one of its ancestor thread groups. Parameters: g - a thread group. Returns: true if this thread group is the thread group argument or one of its ancestor thread groups; false otherwise. Since: JDK1.0
void	resume() copy-> .resume() copy-> <ThreadGroup>.resume(); Deprecated. This method is used solely in conjunction with Thread.suspend and ThreadGroup.suspend, both of which have been deprecated, as they are inherently deadlock-prone. See Thread.suspend() for details. Resumes all threads in this thread group. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. This method then calls the resume method on all the threads in this thread group and in all of its sub groups. Throws: SecurityException - if the current thread is not allowed to access this thread group or any of the threads in the thread group. Since: JDK1.0 See Also: SecurityException, Thread.resume(), checkAccess()
void	setDaemon(boolean daemon) copy-> .setDaemon( ) copy-> <ThreadGroup>.setDaemon(<boolean daemon>); Changes the daemon status of this thread group. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. A daemon thread group is automatically destroyed when its last thread is stopped or its last thread group is destroyed. Parameters: daemon - if true, marks this thread group as a daemon thread group; otherwise, marks this thread group as normal. Throws: SecurityException - if the current thread cannot modify this thread group. Since: JDK1.0 See Also: SecurityException, checkAccess()
void	setMaxPriority(int pri) copy-> .setMaxPriority( ) copy-> <ThreadGroup>.setMaxPriority(<int pri>); Sets the maximum priority of the group. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. Threads in the thread group that already have a higher priority are not affected. Parameters: pri - the new priority of the thread group. Throws: SecurityException - if the current thread cannot modify this thread group. Since: JDK1.0 See Also: getMaxPriority(), SecurityException, checkAccess()
void	stop() copy-> .stop() copy-> <ThreadGroup>.stop(); Deprecated. This method is inherently unsafe. See Thread.stop() for details. Stops all threads in this thread group. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. This method then calls the stop method on all the threads in this thread group and in all of its subgroups. Throws: SecurityException - if the current thread is not allowed to access this thread group or any of the threads in the thread group. Since: JDK1.0 See Also: SecurityException, Thread.stop(), checkAccess()
void	suspend() copy-> .suspend() copy-> <ThreadGroup>.suspend(); Deprecated. This method is inherently deadlock-prone. See Thread.suspend() for details. Suspends all threads in this thread group. First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception. This method then calls the suspend method on all the threads in this thread group and in all of its subgroups. Throws: SecurityException - if the current thread is not allowed to access this thread group or any of the threads in the thread group. Since: JDK1.0 See Also: Thread.suspend(), SecurityException, checkAccess()
String	toString() copy-> .toString() copy-> <String var>=<ThreadGroup>.toString(); Returns a string representation of this Thread group. Overrides: toString in class Object Returns: a string representation of this thread group. Since: JDK1.0
void	uncaughtException(Thread t, Throwable e) copy-> .uncaughtException(, ) copy-> <ThreadGroup>.uncaughtException(<Thread t>, <Throwable e>); Called by the Java Virtual Machine when a thread in this thread group stops because of an uncaught exception. The uncaughtException method of ThreadGroup does the following: If this thread group has a parent thread group, the uncaughtException method of that parent is called with the same two arguments. Otherwise, this method determines if the Throwable argument is an instance of ThreadDeath. If so, nothing special is done. Otherwise, the Throwable's printStackTrace method is called to print a stack backtrace to the standard error stream. Applications can override this method in subclasses of ThreadGroup to provide alternative handling of uncaught exceptions. Parameters: t - the thread that is about to exit. e - the uncaught exception. Since: JDK1.0 See Also: System.err, ThreadDeath, Throwable.printStackTrace(java.io.PrintStream)

Methods inherited from class java.lang.Object

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