public classThreadextendsObjectimplementsRunnable
Every thread has a priority. Threads with higher priority are executed in preference to threads with lower priority. Each thread may or may not also be marked as a daemon. When code running in some thread creates a newThread object, the new thread has its priority initially set equal to the priority of the creating thread, and is a daemon thread if and only if the creating thread is a daemon.
When a Java Virtual Machine starts up, there is usually a single non-daemon thread (which typically calls the method namedmain of some designated class). The Java Virtual Machine continues to execute threads until either of the following occurs:
exit method of classRuntime has been called and the security manager has permitted the exit operation to take place.run method or by throwing an exception that propagates beyond therun method. There are two ways to create a new thread of execution. One is to declare a class to be a subclass ofThread. This subclass should override therun method of classThread. An instance of the subclass can then be allocated and started. For example, a thread that computes primes larger than a stated value could be written as follows:
class PrimeThread extends Thread { long minPrime; PrimeThread(long minPrime) { this.minPrime = minPrime; } public void run() { // compute primes larger than minPrime . . . } }The following code would then create a thread and start it running:
PrimeThread p = new PrimeThread(143); p.start();
The other way to create a thread is to declare a class that implements theRunnable interface. That class then implements therun method. An instance of the class can then be allocated, passed as an argument when creatingThread, and started. The same example in this other style looks like the following:
class PrimeRun implements Runnable { long minPrime; PrimeRun(long minPrime) { this.minPrime = minPrime; } public void run() { // compute primes larger than minPrime . . . } }The following code would then create a thread and start it running:
PrimeRun p = new PrimeRun(143); new Thread(p).start();
Every thread has a name for identification purposes. More than one thread may have the same name. If a name is not specified when a thread is created, a new name is generated for it.
Unless otherwise noted, passing anull argument to a constructor or method in this class will cause aNullPointerException to be thrown.
Runnable,Runtime.exit(int),run(),stop()| Modifier and Type | Class | Description |
|---|---|---|
static class | Thread.State | A thread state. |
static interface | Thread.UncaughtExceptionHandler | Interface for handlers invoked when aThread abruptly terminates due to an uncaught exception. |
| Modifier and Type | Field | Description |
|---|---|---|
static int | MAX_PRIORITY | The maximum priority that a thread can have. |
static int | MIN_PRIORITY | The minimum priority that a thread can have. |
static int | NORM_PRIORITY | The default priority that is assigned to a thread. |
| Constructor | Description |
|---|---|
Thread() | Allocates a new Thread object. |
Thread(Runnable target) | Allocates a new Thread object. |
Thread(Runnable target,String name) | Allocates a new Thread object. |
Thread(String name) | Allocates a new Thread object. |
Thread(ThreadGroup group,Runnable target) | Allocates a new Thread object. |
Thread(ThreadGroup group,Runnable target,String name) | Allocates a new Thread object so that it hastarget as its run object, has the specifiedname as its name, and belongs to the thread group referred to bygroup. |
Thread(ThreadGroup group,Runnable target,String name, long stackSize) | Allocates a new Thread object so that it hastarget as its run object, has the specifiedname as its name, and belongs to the thread group referred to bygroup, and has the specifiedstack size. |
Thread(ThreadGroup group,String name) | Allocates a new Thread object. |
| Modifier and Type | Method | Description |
|---|---|---|
static int | activeCount() | Returns an estimate of the number of active threads in the current thread'sthread group and its subgroups. |
void | checkAccess() | Determines if the currently running thread has permission to modify this thread. |
protectedObject | clone() | Throws CloneNotSupportedException as a Thread can not be meaningfully cloned. |
int | countStackFrames() | Deprecated. The definition of this call depends on suspend(), which is deprecated. Further, the results of this call were never well-defined. |
staticThread | currentThread() | Returns a reference to the currently executing thread object. |
void | destroy() | Deprecated. This method was originally designed to destroy this thread without any cleanup. Any monitors it held would have remained locked. However, the method was never implemented. If if were to be implemented, it would be deadlock-prone in much the manner of suspend(). If the target thread held a lock protecting a critical system resource when it was destroyed, no thread could ever access this resource again. If another thread ever attempted to lock this resource, deadlock would result. Such deadlocks typically manifest themselves as "frozen" processes. For more information, see Why are Thread.stop, Thread.suspend and Thread.resume Deprecated?. |
static void | dumpStack() | Prints a stack trace of the current thread to the standard error stream. |
static int | enumerate(Thread[] tarray) | Copies into the specified array every active thread in the current thread's thread group and its subgroups. |
staticMap<Thread,StackTraceElement[]> | getAllStackTraces() | Returns a map of stack traces for all live threads. |
ClassLoader | getContextClassLoader() | Returns the context ClassLoader for this Thread. |
staticThread.UncaughtExceptionHandler | getDefaultUncaughtExceptionHandler() | Returns the default handler invoked when a thread abruptly terminates due to an uncaught exception. |
long | getId() | Returns the identifier of this Thread. |
String | getName() | Returns this thread's name. |
int | getPriority() | Returns this thread's priority. |
StackTraceElement[] | getStackTrace() | Returns an array of stack trace elements representing the stack dump of this thread. |
Thread.State | getState() | Returns the state of this thread. |
ThreadGroup | getThreadGroup() | Returns the thread group to which this thread belongs. |
Thread.UncaughtExceptionHandler | getUncaughtExceptionHandler() | Returns the handler invoked when this thread abruptly terminates due to an uncaught exception. |
static boolean | holdsLock(Object obj) | Returnstrue if and only if the current thread holds the monitor lock on the specified object. |
void | interrupt() | Interrupts this thread. |
static boolean | interrupted() | Tests whether the current thread has been interrupted. |
boolean | isAlive() | Tests if this thread is alive. |
boolean | isDaemon() | Tests if this thread is a daemon thread. |
boolean | isInterrupted() | Tests whether this thread has been interrupted. |
void | join() | Waits for this thread to die. |
void | join(long millis) | Waits at most millis milliseconds for this thread to die. |
void | join(long millis, int nanos) | Waits at most millis milliseconds plusnanos nanoseconds for this thread to die. |
void | resume() | Deprecated. This method exists solely for use with suspend(), which has been deprecated because it is deadlock-prone. For more information, seeWhy are Thread.stop, Thread.suspend and Thread.resume Deprecated?. |
void | run() | If this thread was constructed using a separate Runnable run object, then thatRunnable object'srun method is called; otherwise, this method does nothing and returns. |
void | setContextClassLoader(ClassLoader cl) | Sets the context ClassLoader for this Thread. |
void | setDaemon(boolean on) | Marks this thread as either adaemon thread or a user thread. |
static void | setDefaultUncaughtExceptionHandler(Thread.UncaughtExceptionHandler eh) | Set the default handler invoked when a thread abruptly terminates due to an uncaught exception, and no other handler has been defined for that thread. |
void | setName(String name) | Changes the name of this thread to be equal to the argument name. |
void | setPriority(int newPriority) | Changes the priority of this thread. |
void | setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler eh) | Set the handler invoked when this thread abruptly terminates due to an uncaught exception. |
static void | sleep(long millis) | Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds, subject to the precision and accuracy of system timers and schedulers. |
static void | sleep(long millis, int nanos) | Causes the currently executing thread to sleep (temporarily cease execution) for the specified number of milliseconds plus the specified number of nanoseconds, subject to the precision and accuracy of system timers and schedulers. |
void | start() | Causes this thread to begin execution; the Java Virtual Machine calls the run method of this thread. |
void | stop() | Deprecated. This method is inherently unsafe. Stopping a thread with Thread.stop causes it to unlock all of the monitors that it has locked (as a natural consequence of the unchecked ThreadDeath exception propagating up the stack). If any of the objects previously protected by these monitors were in an inconsistent state, the damaged objects become visible to other threads, potentially resulting in arbitrary behavior. Many uses ofstop should be replaced by code that simply modifies some variable to indicate that the target thread should stop running. The target thread should check this variable regularly, and return from its run method in an orderly fashion if the variable indicates that it is to stop running. If the target thread waits for long periods (on a condition variable, for example), theinterrupt method should be used to interrupt the wait. For more information, seeWhy are Thread.stop, Thread.suspend and Thread.resume Deprecated?. |
void | stop(Throwable obj) | Deprecated. This method was originally designed to force a thread to stop and throw a given Throwable as an exception. It was inherently unsafe (seestop() for details), and furthermore could be used to generate exceptions that the target thread was not prepared to handle. For more information, seeWhy are Thread.stop, Thread.suspend and Thread.resume Deprecated?. |
void | suspend() | Deprecated. This method has been deprecated, as it is inherently deadlock-prone. If the target thread holds a lock on the monitor protecting a critical system resource when it is suspended, no thread can access this resource until the target thread is resumed. If the thread that would resume the target thread attempts to lock this monitor prior to calling resume, deadlock results. Such deadlocks typically manifest themselves as "frozen" processes. For more information, seeWhy are Thread.stop, Thread.suspend and Thread.resume Deprecated?. |
String | toString() | Returns a string representation of this thread, including the thread's name, priority, and thread group. |
static void | yield() | A hint to the scheduler that the current thread is willing to yield its current use of a processor. |
public static final int MIN_PRIORITY
public static final int NORM_PRIORITY
public static final int MAX_PRIORITY
public Thread()
Thread object. This constructor has the same effect asThread(null, null, gname), wheregname is a newly generated name. Automatically generated names are of the form"Thread-"+n, wheren is an integer.public Thread(Runnable target)
Thread object. This constructor has the same effect asThread(null, target, gname), wheregname is a newly generated name. Automatically generated names are of the form"Thread-"+n, wheren is an integer.target - the object whoserun method is invoked when this thread is started. Ifnull, this classesrun method does nothing.public Thread(ThreadGroup group,Runnable target)
Thread object. This constructor has the same effect asThread(group, target, gname) ,wheregname is a newly generated name. Automatically generated names are of the form"Thread-"+n, wheren is an integer.group - the thread group. Ifnull and there is a security manager, the group is determined bySecurityManager.getThreadGroup(). If there is not a security manager orSecurityManager.getThreadGroup() returnsnull, the group is set to the current thread's thread group.target - the object whoserun method is invoked when this thread is started. Ifnull, this thread's run method is invoked.SecurityException - if the current thread cannot create a thread in the specified thread grouppublic Thread(String name)
name - the name of the new threadpublic Thread(ThreadGroup group,String name)
group - the thread group. Ifnull and there is a security manager, the group is determined bySecurityManager.getThreadGroup(). If there is not a security manager orSecurityManager.getThreadGroup() returnsnull, the group is set to the current thread's thread group.name - the name of the new threadSecurityException - if the current thread cannot create a thread in the specified thread grouppublic Thread(Runnable target,String name)
target - the object whoserun method is invoked when this thread is started. Ifnull, this thread's run method is invoked.name - the name of the new threadpublic Thread(ThreadGroup group,Runnable target,String name)
Thread object so that it hastarget as its run object, has the specifiedname as its name, and belongs to the thread group referred to bygroup.If there is a security manager, itscheckAccess method is invoked with the ThreadGroup as its argument.
In addition, itscheckPermission method is invoked with theRuntimePermission("enableContextClassLoaderOverride") permission when invoked directly or indirectly by the constructor of a subclass which overrides thegetContextClassLoader orsetContextClassLoader methods.
The priority of the newly created thread is set equal to the priority of the thread creating it, that is, the currently running thread. The methodsetPriority may be used to change the priority to a new value.
The newly created thread is initially marked as being a daemon thread if and only if the thread creating it is currently marked as a daemon thread. The methodsetDaemon may be used to change whether or not a thread is a daemon.
group - the thread group. Ifnull and there is a security manager, the group is determined bySecurityManager.getThreadGroup(). If there is not a security manager orSecurityManager.getThreadGroup() returnsnull, the group is set to the current thread's thread group.target - the object whoserun method is invoked when this thread is started. Ifnull, this thread's run method is invoked.name - the name of the new threadSecurityException - if the current thread cannot create a thread in the specified thread group or cannot override the context class loader methods.public Thread(ThreadGroup group,Runnable target,String name, long stackSize)
Thread object so that it hastarget as its run object, has the specifiedname as its name, and belongs to the thread group referred to bygroup, and has the specifiedstack size.This constructor is identical toThread(ThreadGroup,Runnable,String) with the exception of the fact that it allows the thread stack size to be specified. The stack size is the approximate number of bytes of address space that the virtual machine is to allocate for this thread's stack.The effect of thestackSize parameter, if any, is highly platform dependent.
On some platforms, specifying a higher value for thestackSize parameter may allow a thread to achieve greater recursion depth before throwing aStackOverflowError. Similarly, specifying a lower value may allow a greater number of threads to exist concurrently without throwing anOutOfMemoryError (or other internal error). The details of the relationship between the value of thestackSize parameter and the maximum recursion depth and concurrency level are platform-dependent.On some platforms, the value of thestackSize parameter may have no effect whatsoever.
The virtual machine is free to treat thestackSize parameter as a suggestion. If the specified value is unreasonably low for the platform, the virtual machine may instead use some platform-specific minimum value; if the specified value is unreasonably high, the virtual machine may instead use some platform-specific maximum. Likewise, the virtual machine is free to round the specified value up or down as it sees fit (or to ignore it completely).
Specifying a value of zero for thestackSize parameter will cause this constructor to behave exactly like theThread(ThreadGroup, Runnable, String) constructor.
Due to the platform-dependent nature of the behavior of this constructor, extreme care should be exercised in its use. The thread stack size necessary to perform a given computation will likely vary from one JRE implementation to another. In light of this variation, careful tuning of the stack size parameter may be required, and the tuning may need to be repeated for each JRE implementation on which an application is to run.
Implementation note: Java platform implementers are encouraged to document their implementation's behavior with respect to thestackSize parameter.
group - the thread group. Ifnull and there is a security manager, the group is determined bySecurityManager.getThreadGroup(). If there is not a security manager orSecurityManager.getThreadGroup() returnsnull, the group is set to the current thread's thread group.target - the object whoserun method is invoked when this thread is started. Ifnull, this thread's run method is invoked.name - the name of the new threadstackSize - the desired stack size for the new thread, or zero to indicate that this parameter is to be ignored.SecurityException - if the current thread cannot create a thread in the specified thread grouppublic static Thread currentThread()
public static void yield()
Yield is a heuristic attempt to improve relative progression between threads that would otherwise over-utilise a CPU. Its use should be combined with detailed profiling and benchmarking to ensure that it actually has the desired effect.
It is rarely appropriate to use this method. It may be useful for debugging or testing purposes, where it may help to reproduce bugs due to race conditions. It may also be useful when designing concurrency control constructs such as the ones in thejava.util.concurrent.locks package.
public static void sleep(long millis) throwsInterruptedException
millis - the length of time to sleep in millisecondsIllegalArgumentException - if the value ofmillis is negativeInterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.public static void sleep(long millis, int nanos) throwsInterruptedException
millis - the length of time to sleep in millisecondsnanos -0-999999 additional nanoseconds to sleepIllegalArgumentException - if the value ofmillis is negative, or the value ofnanos is not in the range0-999999InterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.protected Object clone() throwsCloneNotSupportedException
clone in class ObjectCloneNotSupportedException - alwaysCloneablepublic void start()
run method of this thread. The result is that two threads are running concurrently: the current thread (which returns from the call to thestart method) and the other thread (which executes itsrun method).
It is never legal to start a thread more than once. In particular, a thread may not be restarted once it has completed execution.
IllegalThreadStateException - if the thread was already started.run(),stop()public void run()
Runnable run object, then thatRunnable object'srun method is called; otherwise, this method does nothing and returns. Subclasses ofThread should override this method.
run in interface Runnablestart(),stop(),Thread(ThreadGroup, Runnable, String)@Deprecatedpublic final void stop()
ThreadDeath exception propagating up the stack). If any of the objects previously protected by these monitors were in an inconsistent state, the damaged objects become visible to other threads, potentially resulting in arbitrary behavior. Many uses ofstop should be replaced by code that simply modifies some variable to indicate that the target thread should stop running. The target thread should check this variable regularly, and return from its run method in an orderly fashion if the variable indicates that it is to stop running. If the target thread waits for long periods (on a condition variable, for example), theinterrupt method should be used to interrupt the wait. For more information, seeWhy are Thread.stop, Thread.suspend and Thread.resume Deprecated?. If there is a security manager installed, itscheckAccess method is called withthis as its argument. This may result in aSecurityException being raised (in the current thread).
If this thread is different from the current thread (that is, the current thread is trying to stop a thread other than itself), the security manager'scheckPermission method (with aRuntimePermission("stopThread") argument) is called in addition. Again, this may result in throwing aSecurityException (in the current thread).
The thread represented by this thread is forced to stop whatever it is doing abnormally and to throw a newly createdThreadDeath object as an exception.
It is permitted to stop a thread that has not yet been started. If the thread is eventually started, it immediately terminates.
An application should not normally try to catchThreadDeath unless it must do some extraordinary cleanup operation (note that the throwing ofThreadDeath causesfinally clauses oftry statements to be executed before the thread officially dies). If acatch clause catches aThreadDeath object, it is important to rethrow the object so that the thread actually dies.
The top-level error handler that reacts to otherwise uncaught exceptions does not print out a message or otherwise notify the application if the uncaught exception is an instance ofThreadDeath.
SecurityException - if the current thread cannot modify this thread.interrupt(),checkAccess(),run(),start(),ThreadDeath,ThreadGroup.uncaughtException(Thread,Throwable),SecurityManager.checkAccess(Thread),SecurityManager.checkPermission(java.security.Permission)@Deprecatedpublic final void stop(Throwable obj)
Throwable as an exception. It was inherently unsafe (seestop() for details), and furthermore could be used to generate exceptions that the target thread was not prepared to handle. For more information, seeWhy are Thread.stop, Thread.suspend and Thread.resume Deprecated?.UnsupportedOperationException.obj - ignoredpublic void interrupt()
Unless the current thread is interrupting itself, which is always permitted, thecheckAccess method of this thread is invoked, which may cause aSecurityException to be thrown.
If this thread is blocked in an invocation of thewait(),wait(long), orwait(long, int) methods of theObject class, or of thejoin(),join(long),join(long, int),sleep(long), orsleep(long, int), methods of this class, then its interrupt status will be cleared and it will receive anInterruptedException.
If this thread is blocked in an I/O operation upon anInterruptibleChannel then the channel will be closed, the thread's interrupt status will be set, and the thread will receive aClosedByInterruptException.
If this thread is blocked in aSelector then the thread's interrupt status will be set and it will return immediately from the selection operation, possibly with a non-zero value, just as if the selector'swakeup method were invoked.
If none of the previous conditions hold then this thread's interrupt status will be set.
Interrupting a thread that is not alive need not have any effect.
SecurityException - if the current thread cannot modify this threadpublic static boolean interrupted()
A thread interruption ignored because a thread was not alive at the time of the interrupt will be reflected by this method returning false.
true if the current thread has been interrupted;false otherwise.isInterrupted()public boolean isInterrupted()
A thread interruption ignored because a thread was not alive at the time of the interrupt will be reflected by this method returning false.
true if this thread has been interrupted;false otherwise.interrupted()@Deprecatedpublic void destroy()
suspend(). If the target thread held a lock protecting a critical system resource when it was destroyed, no thread could ever access this resource again. If another thread ever attempted to lock this resource, deadlock would result. Such deadlocks typically manifest themselves as "frozen" processes. For more information, see Why are Thread.stop, Thread.suspend and Thread.resume Deprecated?.NoSuchMethodError.NoSuchMethodError - alwayspublic final boolean isAlive()
true if this thread is alive;false otherwise.@Deprecatedpublic final void suspend()
resume, deadlock results. Such deadlocks typically manifest themselves as "frozen" processes. For more information, seeWhy are Thread.stop, Thread.suspend and Thread.resume Deprecated?. First, thecheckAccess method of this thread is called with no arguments. This may result in throwing aSecurityException(in the current thread).
If the thread is alive, it is suspended and makes no further progress unless and until it is resumed.
SecurityException - if the current thread cannot modify this thread.checkAccess()@Deprecatedpublic final void resume()
suspend(), which has been deprecated because it is deadlock-prone. For more information, seeWhy are Thread.stop, Thread.suspend and Thread.resume Deprecated?. First, thecheckAccess method of this thread is called with no arguments. This may result in throwing aSecurityException (in the current thread).
If the thread is alive but suspended, it is resumed and is permitted to make progress in its execution.
SecurityException - if the current thread cannot modify this thread.checkAccess(),suspend()public final void setPriority(int newPriority)
First thecheckAccess method of this thread is called with no arguments. This may result in throwing aSecurityException.
Otherwise, the priority of this thread is set to the smaller of the specifiednewPriority and the maximum permitted priority of the thread's thread group.
newPriority - priority to set this thread toIllegalArgumentException - If the priority is not in the rangeMIN_PRIORITY toMAX_PRIORITY.SecurityException - if the current thread cannot modify this thread.getPriority(),checkAccess(),getThreadGroup(),MAX_PRIORITY,MIN_PRIORITY,ThreadGroup.getMaxPriority()public final int getPriority()
setPriority(int)public final void setName(String name)
name. First thecheckAccess method of this thread is called with no arguments. This may result in throwing aSecurityException.
name - the new name for this thread.SecurityException - if the current thread cannot modify this thread.getName(),checkAccess()public final String getName()
setName(String)public final ThreadGroup getThreadGroup()
public static int activeCount()
The value returned is only an estimate because the number of threads may change dynamically while this method traverses internal data structures, and might be affected by the presence of certain system threads. This method is intended primarily for debugging and monitoring purposes.
public static int enumerate(Thread[] tarray)
ThreadGroup.enumerate(Thread[]) method of the current thread's thread group. An application might use theactiveCount method to get an estimate of how big the array should be, howeverif 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 the current thread's thread group and its subgroups, the invoker should verify that the returned int value is strictly less than the length oftarray.
Due to the inherent race condition in this method, it is recommended that the method only be used for debugging and monitoring purposes.
tarray - an array into which to put the list of threadsSecurityException - ifThreadGroup.checkAccess() determines that the current thread cannot access its thread group@Deprecatedpublic int countStackFrames()
suspend(), which is deprecated. Further, the results of this call were never well-defined.IllegalThreadStateException - if this thread is not suspended.public final void join(long millis) throwsInterruptedException
millis milliseconds for this thread to die. A timeout of0 means to wait forever. This implementation uses a loop ofthis.wait calls conditioned onthis.isAlive. As a thread terminates thethis.notifyAll method is invoked. It is recommended that applications not usewait,notify, ornotifyAll onThread instances.
millis - the time to wait in millisecondsIllegalArgumentException - if the value ofmillis is negativeInterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.public final void join(long millis, int nanos) throwsInterruptedException
millis milliseconds plusnanos nanoseconds for this thread to die. This implementation uses a loop ofthis.wait calls conditioned onthis.isAlive. As a thread terminates thethis.notifyAll method is invoked. It is recommended that applications not usewait,notify, ornotifyAll onThread instances.
millis - the time to wait in millisecondsnanos -0-999999 additional nanoseconds to waitIllegalArgumentException - if the value ofmillis is negative, or the value ofnanos is not in the range0-999999InterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.public final void join() throwsInterruptedException
An invocation of this method behaves in exactly the same way as the invocation
join(0)InterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.public static void dumpStack()
Throwable.printStackTrace()public final void setDaemon(boolean on)
This method must be invoked before the thread is started.
on - iftrue, marks this thread as a daemon threadIllegalThreadStateException - if this thread isaliveSecurityException - ifcheckAccess() determines that the current thread cannot modify this threadpublic final boolean isDaemon()
true if this thread is a daemon thread;false otherwise.setDaemon(boolean)public final void checkAccess()
If there is a security manager, itscheckAccess method is called with this thread as its argument. This may result in throwing aSecurityException.
SecurityException - if the current thread is not allowed to access this thread.SecurityManager.checkAccess(Thread)public String toString()
public ClassLoader getContextClassLoader()
If a security manager is present, and the invoker's class loader is notnull and is not the same as or an ancestor of the context class loader, then this method invokes the security manager'scheckPermission method with aRuntimePermission("getClassLoader") permission to verify that retrieval of the context class loader is permitted.
null indicating the system class loader (or, failing that, the bootstrap class loader)SecurityException - if the current thread cannot get the context ClassLoaderpublic void setContextClassLoader(ClassLoader cl)
getContextClassLoader, to code running in the thread when loading classes and resources.If a security manager is present, itscheckPermission method is invoked with aRuntimePermission("setContextClassLoader") permission to see if setting the context ClassLoader is permitted.
cl - the context ClassLoader for this Thread, or null indicating the system class loader (or, failing that, the bootstrap class loader)SecurityException - if the current thread cannot set the context ClassLoaderpublic static boolean holdsLock(Object obj)
This method is designed to allow a program to assert that the current thread already holds a specified lock:
assert Thread.holdsLock(obj);
obj - the object on which to test lock ownershipNullPointerException - if obj isnullpublic StackTraceElement[] getStackTrace()
If there is a security manager, and this thread is not the current thread, then the security manager'scheckPermission method is called with aRuntimePermission("getStackTrace") permission to see if it's ok to get the stack trace.
Some virtual machines may, under some circumstances, omit one or more stack frames from the stack trace. In the extreme case, a virtual machine that has no stack trace information concerning this thread is permitted to return a zero-length array from this method.
SecurityException - if a security manager exists and itscheckPermission method doesn't allow getting the stack trace of thread.SecurityManager.checkPermission(java.security.Permission),RuntimePermission,Throwable.getStackTrace()public static Map<Thread,StackTraceElement[]> getAllStackTraces()
getStackTrace method.The threads may be executing while this method is called. The stack trace of each thread only represents a snapshot and each stack trace may be obtained at different time. A zero-length array will be returned in the map value if the virtual machine has no stack trace information about a thread.
If there is a security manager, then the security manager'scheckPermission method is called with aRuntimePermission("getStackTrace") permission as well asRuntimePermission("modifyThreadGroup") permission to see if it is ok to get the stack trace of all threads.
SecurityException - if a security manager exists and itscheckPermission method doesn't allow getting the stack trace of thread.getStackTrace(),SecurityManager.checkPermission(java.security.Permission),RuntimePermission,Throwable.getStackTrace()public long getId()
public Thread.State getState()
public static void setDefaultUncaughtExceptionHandler(Thread.UncaughtExceptionHandler eh)
Uncaught exception handling is controlled first by the thread, then by the thread'sThreadGroup object and finally by the default uncaught exception handler. If the thread does not have an explicit uncaught exception handler set, and the thread's thread group (including parent thread groups) does not specialize itsuncaughtException method, then the default handler'suncaughtException method will be invoked.
By setting the default uncaught exception handler, an application can change the way in which uncaught exceptions are handled (such as logging to a specific device, or file) for those threads that would already accept whatever "default" behavior the system provided.
Note that the default uncaught exception handler should not usually defer to the thread'sThreadGroup object, as that could cause infinite recursion.
eh - the object to use as the default uncaught exception handler. Ifnull then there is no default handler.SecurityException - if a security manager is present and it deniesRuntimePermission ("setDefaultUncaughtExceptionHandler")setUncaughtExceptionHandler(java.lang.Thread.UncaughtExceptionHandler),getUncaughtExceptionHandler(),ThreadGroup.uncaughtException(java.lang.Thread, java.lang.Throwable)public static Thread.UncaughtExceptionHandler getDefaultUncaughtExceptionHandler()
setDefaultUncaughtExceptionHandler(java.lang.Thread.UncaughtExceptionHandler)public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler()
public void setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler eh)
A thread can take full control of how it responds to uncaught exceptions by having its uncaught exception handler explicitly set. If no such handler is set then the thread'sThreadGroup object acts as its handler.
eh - the object to use as this thread's uncaught exception handler. Ifnull then this thread has no explicit handler.SecurityException - if the current thread is not allowed to modify this thread.setDefaultUncaughtExceptionHandler(java.lang.Thread.UncaughtExceptionHandler),ThreadGroup.uncaughtException(java.lang.Thread, java.lang.Throwable)