java.lang.Object java.lang.ThreadGroup
public class ThreadGroup
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.
Constructor Summary | |
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ThreadGroup
(
String
name) Constructs a new thread group. |
|
ThreadGroup
(
ThreadGroup
parent,
String
name) Creates a new thread group. |
Method Summary | |
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int |
activeCount
() Returns an estimate of the number of active threads in this thread group. |
int |
activeGroupCount
() Returns an estimate of the number of active groups in this thread group. |
boolean |
allowThreadSuspension
(boolean b) Deprecated. The definition of this call depends on suspend() , which is deprecated. Further, the behavior of this call was never specified. |
void |
checkAccess
() Determines if the currently running thread has permission to modify this thread group. |
void |
destroy
() Destroys this thread group and all of its subgroups. |
int |
enumerate
(
Thread
[] list) Copies into the specified array every active thread in this thread group and its subgroups. |
int |
enumerate
(
Thread
[] list, boolean recurse) Copies into the specified array every active thread in this thread group. |
int |
enumerate
(
ThreadGroup
[] list) Copies into the specified array references to every active subgroup in this thread group. |
int |
enumerate
(
ThreadGroup
[] list, boolean recurse) Copies into the specified array references to every active subgroup in this thread group. |
int |
getMaxPriority
() Returns the maximum priority of this thread group. |
String |
getName
() Returns the name of this thread group. |
ThreadGroup |
getParent
() Returns the parent of this thread group. |
void |
interrupt
() Interrupts all threads in this thread group. |
boolean |
isDaemon
() Tests if this thread group is a daemon thread group. |
boolean |
isDestroyed
() Tests if this thread group has been destroyed. |
void |
list
() Prints information about this thread group to the standard output. |
boolean |
parentOf
(
ThreadGroup
g) Tests if this thread group is either the thread group argument or one of its ancestor thread groups. |
void |
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. |
void |
setDaemon
(boolean daemon) Changes the daemon status of this thread group. |
void |
setMaxPriority
(int pri) Sets the maximum priority of the group. |
void |
stop
() Deprecated. This method is inherently unsafe. See Thread.stop() for details. |
void |
suspend
() Deprecated. This method is inherently deadlock-prone. See Thread.suspend() for details. |
String |
toString
() Returns a string representation of this Thread group. |
void |
uncaughtException
(
Thread
t,
Throwable
e) Called by the Java Virtual Machine when a thread in this thread group stops because of an uncaught exception, and the thread does not have a specific Thread.UncaughtExceptionHandler installed. |
Methods inherited from class java.lang. Object |
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clone , equals , finalize , getClass , hashCode , notify , notifyAll , wait , wait , wait |
Constructor Detail |
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public ThreadGroup(String name)
The checkAccess method of the parent thread group is called with no arguments; this may result in a security exception.
public ThreadGroup(ThreadGroup parent, String name)
The checkAccess method of the parent thread group is called with no arguments; this may result in a security exception.
Method Detail |
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public final String getName()
public final ThreadGroup getParent()
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.
public final int getMaxPriority()
public final boolean isDaemon()
public boolean isDestroyed()
public final void setDaemon(boolean daemon)
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.
public final void setMaxPriority(int pri)
First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception.
If the pri argument is less than Thread.MIN_PRIORITY or greater than Thread.MAX_PRIORITY , the maximum priority of the group remains unchanged.
Otherwise, the priority of this ThreadGroup object is set to the smaller of the specified pri and the maximum permitted priority of the parent of this thread group. (If this thread group is the system thread group, which has no parent, then its maximum priority is simply set to pri.) Then this method is called recursively, with pri as its argument, for every thread group that belongs to this thread group.
public final boolean parentOf(ThreadGroup g)
public final void checkAccess()
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.
public int activeCount()
Due to the inherently imprecise nature of the result, it is recommended that this method only be used for informational purposes.
public int enumerate(Thread[] list)
First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception.
An application might use the activeCount method to get an estimate of how big the array should be, however if the array is too short to hold all the threads, the extra threads are silently ignored. If it is critical to obtain every active thread in this thread group and its subgroups, the caller should verify that the returned int value is strictly less than the length of list .
Due to the inherent race condition in this method, it is recommended that the method only be used for informational purposes.
public int enumerate(Thread[] list, boolean recurse)
First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception.
An application might use the activeCount method to get an estimate of how big the array should be, however if the array is too short to hold all the threads, the extra threads are silently ignored. If it is critical to obtain every active thread in this thread group, the caller should verify that the returned int value is strictly less than the length of list .
Due to the inherent race condition in this method, it is recommended that the method only be used for informational purposes.
public int activeGroupCount()
Due to the inherently imprecise nature of the result, it is recommended that this method only be used for informational purposes.
public int enumerate(ThreadGroup[] list)
First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception.
An application might use the activeGroupCount method to get an estimate of how big the array should be, however if the array is too short to hold all the thread groups, the extra thread groups are silently ignored. If it is critical to obtain every active subgroup in this thread group, the caller should verify that the returned int value is strictly less than the length of list .
Due to the inherent race condition in this method, it is recommended that the method only be used for informational purposes.
public int enumerate(ThreadGroup[] list, boolean recurse)
First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception.
An application might use the activeGroupCount method to get an estimate of how big the array should be, however if the array is too short to hold all the thread groups, the extra thread groups are silently ignored. If it is critical to obtain every active subgroup in this thread group, the caller should verify that the returned int value is strictly less than the length of list .
Due to the inherent race condition in this method, it is recommended that the method only be used for informational purposes.
@Deprecated public final void stop()
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.
public final void interrupt()
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.
@Deprecated public final void suspend()
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.
@Deprecated public final void resume()
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.
public final void destroy()
First, the checkAccess method of this thread group is called with no arguments; this may result in a security exception.
public void list()
public void uncaughtException(Thread t, Throwable e)
The uncaughtException method of ThreadGroup does the following:
Applications can override this method in subclasses of ThreadGroup to provide alternative handling of uncaught exceptions.
@Deprecated public boolean allowThreadSuspension(boolean b)
public String toString()