Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Field Details

• MIN_PRIORITY

  public static final int MIN_PRIORITY

  The minimum priority that a thread can have.

  See Also:

  • Constant Field Values

• NORM_PRIORITY

  public static final int NORM_PRIORITY

  The default priority that is assigned to a thread.

  See Also:

  • Constant Field Values

• MAX_PRIORITY

  public static final int MAX_PRIORITY

  The maximum priority that a thread can have.

  See Also:

  • Constant Field Values

Constructor Details

• Thread

  public Thread()

  Initializes a new platformThread. This constructor has the sameeffect asThread(null, null, gname), wheregname is a newly generatedname. Automatically generated names are of the form"Thread-"+n, wheren is an integer.

  This constructor is only useful when extendingThread tooverride therun() method.

  See Also:

  • Inheritance when creating threads

• Thread

  public Thread(Runnable task)

  Initializes a new platformThread. This constructor has the sameeffect asThread(null, task, gname), wheregname is a newly generatedname. Automatically generated names are of the form"Thread-"+n, wheren is an integer.

  For a non-null task, invoking this constructor directly is equivalent to:

  Thread.ofPlatform().unstarted(task);

  Parameters:

  task - the object whoserun method is invoked when this thread is started. Ifnull, this classesrun method does nothing.

  See Also:

  • Inheritance when creating threads

• Thread

  public Thread(ThreadGroup group,Runnable task)

  Initializes a new platformThread. This constructor has the sameeffect asThread(group, task, gname), wheregname is a newly generatedname. Automatically generated names are of the form"Thread-"+n, wheren is an integer.

  For a non-null group and task, invoking this constructor directly isequivalent to:

  Thread.ofPlatform().group(group).unstarted(task);

  Parameters:

  group - the thread group. Ifnull the group is set to the current thread's thread group.

  task - the object whoserun method is invoked when this thread is started. Ifnull, this thread's run method is invoked.

  See Also:

  • Inheritance when creating threads

• Thread

  public Thread(String name)

  Initializes a new platformThread. This constructor has the sameeffect asThread(null, null, name).

  This constructor is only useful when extendingThread tooverride therun() method.

  Parameters:

  name - the name of the new thread

  See Also:

  • Inheritance when creating threads

• Thread

  public Thread(ThreadGroup group,String name)

  Initializes a new platformThread. This constructor has the sameeffect asThread(group, null, name).

  This constructor is only useful when extendingThread tooverride therun() method.

  Parameters:

  group - the thread group. Ifnull, the group is set to the current thread's thread group.

  name - the name of the new thread

  See Also:

  • Inheritance when creating threads

• Thread

  public Thread(Runnable task,String name)

  Initializes a new platformThread. This constructor has the sameeffect asThread(null, task, name).

  For a non-null task and name, invoking this constructor directly isequivalent to:

  Thread.ofPlatform().name(name).unstarted(task);

  Parameters:

  task - 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 thread

  See Also:

  • Inheritance when creating threads

• Thread

  public Thread(ThreadGroup group,Runnable task,String name)

  Initializes a new platformThread so that it hastaskas its run object, has the specifiedname as its name,and belongs to the thread group referred to bygroup.

  The priority of the newly created thread is the smaller ofpriority of the thread creating it and the maximum permittedpriority of the thread group. The methodsetPriority may be used to change the priority to a new value.

  The newly created thread is initially marked as being a daemonthread if and only if the thread creating it is currently markedas a daemon thread. The methodsetDaemonmay be used to change whether or not a thread is a daemon.

  For a non-null group, task, and name, invoking this constructor directlyis equivalent to:

  Thread.ofPlatform().group(group).name(name).unstarted(task);

  Parameters:

  group - the thread group. Ifnull, the group is set to the current thread's thread group.

  task - 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 thread

  See Also:

  • Inheritance when creating threads

• Thread

  public Thread(ThreadGroup group,Runnable task,String name, long stackSize)

  Initializes a new platformThread so that it hastaskas its run object, has the specifiedname as its name,and belongs to the thread group referred to bygroup, and hasthe specifiedstack size.

  This constructor is identical toThread(ThreadGroup,Runnable,String) with the exception of the factthat it allows the thread stack size to be specified. The stack sizeis the approximate number of bytes of address space that the virtualmachine 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 greaterrecursion depth before throwing aStackOverflowError.Similarly, specifying a lower value may allow a greater number ofthreads to exist concurrently without throwing anOutOfMemoryError (or other internal error). The details ofthe relationship between the value of thestackSize parameterand the maximum recursion depth and concurrency level areplatform-dependent.On some platforms, the value of thestackSize parameter may have no effect whatsoever.

  The virtual machine is free to treat thestackSizeparameter as a suggestion. If the specified value is unreasonably lowfor the platform, the virtual machine may instead use someplatform-specific minimum value; if the specified value is unreasonablyhigh, the virtual machine may instead use some platform-specificmaximum. Likewise, the virtual machine is free to round the specifiedvalue up or down as it sees fit (or to ignore it completely).

  Specifying a value of zero for thestackSize parameter willcause this constructor to behave exactly like theThread(ThreadGroup, Runnable, String) constructor.

  Due to the platform-dependent nature of the behavior of thisconstructor, extreme care should be exercised in its use.The thread stack size necessary to perform a given computation willlikely vary from one JRE implementation to another. In light of thisvariation, careful tuning of the stack size parameter may be required,and the tuning may need to be repeated for each JRE implementation onwhich an application is to run.

  Implementation note: Java platform implementers are encouraged todocument their implementation's behavior with respect to thestackSize parameter.

  For a non-null group, task, and name, invoking this constructor directlyis equivalent to:

  Thread.ofPlatform().group(group).name(name).stackSize(stackSize).unstarted(task);

  Parameters:

  group - the thread group. Ifnull, the group is set to the current thread's thread group.

  task - 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 thread

  stackSize - the desired stack size for the new thread, or zero to indicate that this parameter is to be ignored.

  Since:

  1.4

  See Also:

  • Inheritance when creating threads

• Thread

  public Thread(ThreadGroup group,Runnable task,String name, long stackSize, boolean inheritInheritableThreadLocals)

  Initializes a new platformThread so that it hastaskas its run object, has the specifiedname as its name,belongs to the thread group referred to bygroup, hasthe specifiedstackSize, and inherits initial values forinheritable thread-local variablesifinheritThreadLocals istrue.

  This constructor is identical toThread(ThreadGroup,Runnable,String,long) with the added ability tosuppress, or not, the inheriting of initial values for inheritablethread-local variables from the constructing thread. This allows forfiner grain control over inheritable thread-locals. Care must be takenwhen passing a value offalse forinheritThreadLocals,as it may lead to unexpected behavior if the new thread executes codethat expects a specific thread-local value to be inherited.

  Specifying a value oftrue for theinheritThreadLocalsparameter will cause this constructor to behave exactly like theThread(ThreadGroup, Runnable, String, long) constructor.

  For a non-null group, task, and name, invoking this constructor directlyis equivalent to:

  Thread.ofPlatform()     .group(group)     .name(name)     .stackSize(stackSize)     .inheritInheritableThreadLocals(inheritInheritableThreadLocals)     .unstarted(task);

  Parameters:

  group - the thread group. Ifnull, the group is set to the current thread's thread group.

  task - 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 thread

  stackSize - the desired stack size for the new thread, or zero to indicate that this parameter is to be ignored

  inheritInheritableThreadLocals - iftrue, inherit initial values for inheritable thread-locals from the constructing thread, otherwise no initial values are inherited

  Since:

  9

  See Also:

  • Inheritance when creating threads

Method Details

• currentThread

  public static Thread currentThread()

  Returns the Thread object for the current thread.

  Returns:

  the current thread

• yield

  public static void yield()

  A hint to the scheduler that the current thread is willing to yieldits current use of a processor. The scheduler is free to ignore thishint.

  Yield is a heuristic attempt to improve relative progressionbetween threads that would otherwise over-utilise a CPU. Its useshould be combined with detailed profiling and benchmarking toensure that it actually has the desired effect.

  It is rarely appropriate to use this method. It may be usefulfor debugging or testing purposes, where it may help to reproducebugs due to race conditions. It may also be useful when designingconcurrency control constructs such as the ones in thejava.util.concurrent.locks package.

• sleep

  public static void sleep(long millis) throwsInterruptedException

  Causes the currently executing thread to sleep (temporarily ceaseexecution) for the specified number of milliseconds, subject tothe precision and accuracy of system timers and schedulers. The threaddoes not lose ownership of any monitors.

  Parameters:

  millis - the length of time to sleep in milliseconds

  Throws:

  IllegalArgumentException - if the value ofmillis is negative

  InterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.

• sleep

  public static void sleep(long millis, int nanos) throwsInterruptedException

  Causes the currently executing thread to sleep (temporarily ceaseexecution) for the specified number of milliseconds plus the specifiednumber of nanoseconds, subject to the precision and accuracy of systemtimers and schedulers. The thread does not lose ownership of anymonitors.

  Parameters:

  millis - the length of time to sleep in milliseconds

  nanos -0-999999 additional nanoseconds to sleep

  Throws:

  IllegalArgumentException - if the value ofmillis is negative, or the value ofnanos is not in the range0-999999

  InterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.

• sleep

  public static void sleep(Duration duration) throwsInterruptedException

  Causes the currently executing thread to sleep (temporarily ceaseexecution) for the specified duration, subject to the precision andaccuracy of system timers and schedulers. This method is a no-op ifthe duration isnegative.

  Parameters:

  duration - the duration to sleep

  Throws:

  InterruptedException - if the current thread is interrupted while sleeping. Theinterrupted status of the current thread is cleared when this exception is thrown.

  Since:

  19

• onSpinWait

  public static void onSpinWait()

  Indicates that the caller is momentarily unable to progress, until theoccurrence of one or more actions on the part of other activities. Byinvoking this method within each iteration of a spin-wait loop construct,the calling thread indicates to the runtime that it is busy-waiting.The runtime may take action to improve the performance of invokingspin-wait loop constructions.

  API Note:

  As an example consider a method in a class that spins in a loop untilsome flag is set outside of that method. A call to theonSpinWaitmethod should be placed inside the spin loop.

  Copy

      class EventHandler {        volatile boolean eventNotificationNotReceived;        void waitForEventAndHandleIt() {            while ( eventNotificationNotReceived ) {                Thread.onSpinWait();            }            readAndProcessEvent();        }        void readAndProcessEvent() {            // Read event from some source and process it             . . .        }    }

  The code above would remain correct even if theonSpinWaitmethod was not called at all. However on some architectures the JavaVirtual Machine may issue the processor instructions to address suchcode patterns in a more beneficial way.

  Since:

  9

• ofPlatform

  public static Thread.Builder.OfPlatform ofPlatform()

  Returns a builder for creating a platformThread orThreadFactorythat creates platform threads.

  API Note:

  The following are examples using the builder:

  Copy

    // Start a daemon thread to run a task  Thread thread = Thread.ofPlatform().daemon().start(runnable);  // Create an unstarted thread with name "duke", its start() method  // must be invoked to schedule it to execute.  Thread thread = Thread.ofPlatform().name("duke").unstarted(runnable);  // A ThreadFactory that creates daemon threads named "worker-0", "worker-1", ...  ThreadFactory factory = Thread.ofPlatform().daemon().name("worker-", 0).factory();

  Returns:

  A builder for creatingThread orThreadFactory objects.

  Since:

  21

• ofVirtual

  public static Thread.Builder.OfVirtual ofVirtual()

  Returns a builder for creating a virtualThread orThreadFactorythat creates virtual threads.

  API Note:

  The following are examples using the builder:

  Copy

    // Start a virtual thread to run a task.  Thread thread = Thread.ofVirtual().start(runnable);  // A ThreadFactory that creates virtual threads  ThreadFactory factory = Thread.ofVirtual().factory();

  Returns:

  A builder for creatingThread orThreadFactory objects.

  Since:

  21

• clone

  protected Object clone() throwsCloneNotSupportedException

  Throws CloneNotSupportedException as a Thread can not be meaningfullycloned. Construct a new Thread instead.

  Overrides:

  clone in class Object

  Returns:

  a clone of this instance.

  Throws:

  CloneNotSupportedException - always

  See Also:

  • Cloneable

• startVirtualThread

  public static Thread startVirtualThread(Runnable task)

  Creates a virtual thread to execute a task and schedules it to execute.

  This method is equivalent to:

  Thread.ofVirtual().start(task);

  Parameters:

  task - the object to run when the thread executes

  Returns:

  a new, and started, virtual thread

  Since:

  21

  See Also:

  • Inheritance when creating threads

• isVirtual

  public final boolean isVirtual()

  Returnstrue if this thread is a virtual thread. A virtual threadis scheduled by the Java virtual machine rather than the operating system.

  Returns:

  true if this thread is a virtual thread

  Since:

  21

• start

  public void start()

  Schedules this thread to begin execution. The thread will executeindependently of the current thread.

  A thread can be started at most once. In particular, a thread can notbe restarted after it has terminated.

  Throws:

  IllegalThreadStateException - if the thread was already started

• run

  public void run()

  This method is run by the thread when it executes. Subclasses ofThread may override this method.

  This method is not intended to be invoked directly. If this thread is aplatform thread created with aRunnable task then invoking this methodwill invoke the task'srun method. If this thread is a virtual threadthen invoking this method directly does nothing.

  Specified by:

  run in interface Runnable

  Implementation Requirements:

  The default implementation executes theRunnable task thattheThread was created with. If the thread was created without a taskthen this method does nothing.

• stop

  @Deprecated(since="1.2",forRemoval=true)public final void stop()

  Deprecated, for removal: This API element is subject to removal in a future version.

  This method was originally specified to "stop" a victim thread by causing the victim thread to throw aThreadDeath. It was inherently unsafe. Stopping a thread caused it to unlock all of the monitors that it had locked (as a natural consequence of theThreadDeath exception propagating up the stack). If any of the objects previously protected by these monitors were in an inconsistent state, the damaged objects became visible to other threads, potentially resulting in arbitrary behavior. Usages 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 is Thread.stop deprecated and the ability to stop a thread removed?.

  ThrowsUnsupportedOperationException.

  Throws:

  UnsupportedOperationException - always

• interrupt

  public void interrupt()

  Interrupts this thread.

  If this thread is blocked in an invocation of thewait(),wait(long), orwait(long, int) methods of theObjectclass, 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 itwill receive anInterruptedException.

  If this thread is blocked in an I/O operation upon anInterruptibleChannelthen the channel will be closed, the thread's interruptstatus will be set, and the thread will receive aClosedByInterruptException.

  If this thread is blocked in aSelectorthen the thread's interrupt status will be set and it will returnimmediately from the selection operation, possibly with a non-zerovalue, just as if the selector'swakeup method were invoked.

  If none of the previous conditions hold then this thread's interruptstatus will be set.

  Interrupting a thread that is not alive need not have any effect.

  Implementation Note:

  In the JDK Reference Implementation, interruption of a threadthat is not alive still records that the interrupt request was made andwill report it viainterrupted() andisInterrupted().

• interrupted

  public static boolean interrupted()

  Tests whether the current thread has been interrupted. Theinterrupted status of the thread is cleared by this method. Inother words, if this method were to be called twice in succession, thesecond call would return false (unless the current thread wereinterrupted again, after the first call had cleared its interruptedstatus and before the second call had examined it).

  Returns:

  true if the current thread has been interrupted;false otherwise.

  See Also:

  • isInterrupted()

• isInterrupted

  public boolean isInterrupted()

  Tests whether this thread has been interrupted. Theinterruptedstatus of the thread is unaffected by this method.

  Returns:

  true if this thread has been interrupted;false otherwise.

  See Also:

  • interrupted()

• isAlive

  public final boolean isAlive()

  Tests if this thread is alive. A thread is alive if it hasbeen started and has not yet terminated.

  Returns:

  true if this thread is alive;false otherwise.

• setPriority

  public final void setPriority(int newPriority)

  Changes the priority of this thread.For platform threads, the priority is set to the smaller of the specifiednewPriority and the maximum permitted priority of the thread'sthread group.The priority of a virtual thread is alwaysNORM_PRIORITYandnewPriority is ignored.

  Parameters:

  newPriority - the new thread priority

  Throws:

  IllegalArgumentException - if the priority is not in the rangeMIN_PRIORITY toMAX_PRIORITY.

  See Also:

  • setPriority(int)
  • ThreadGroup.getMaxPriority()

• getPriority

  public final int getPriority()

  Returns this thread's priority.

  The priority of a virtual thread is alwaysNORM_PRIORITY.

  Returns:

  this thread's priority.

  See Also:

  • setPriority(int)

• setName

  public final void setName(String name)

  Changes the name of this thread to be equal to the argumentname.

  Implementation Note:

  In the JDK Reference Implementation, if this thread is thecurrent thread, and it's a platform thread that was not attached to theVM with the Java Native InterfaceAttachCurrentThread function, then this method will set the operatingsystem thread name. This may be useful for debugging and troubleshootingpurposes.

  Parameters:

  name - the new name for this thread.

  External Specifications

  • Java Native Interface Specification

  See Also:

  • getName()

• getName

  public final String getName()

  Returns this thread's name.

  Returns:

  this thread's name.

  See Also:

  • setName(String)

• getThreadGroup

  public final ThreadGroup getThreadGroup()

  Returns the thread's thread group ornull if the thread hasterminated.

  The thread group returned for a virtual thread is the specialThreadGroup forvirtual threads.

  Returns:

  this thread's thread group ornull

• activeCount

  public static int activeCount()

  Returns an estimate of the number ofliveplatform threads in the current thread's thread group and its subgroups.Virtual threads are not included in the estimate.

  The value returned is only an estimate because the number ofthreads may change dynamically while this method traverses internaldata structures, and might be affected by the presence of certainsystem threads. This method is intended primarily for debuggingand monitoring purposes.

  Returns:

  an estimate of the number of live platform threads in the current thread's thread group and in any other thread group that has the current thread's thread group as an ancestor

• enumerate

  public static int enumerate(Thread[] tarray)

  Copies into the specified array everyliveplatform thread in the current thread's thread group and its subgroups.This method simply invokes theThreadGroup.enumerate(Thread[])method of the current thread's thread group. Virtual threads arenot enumerated by this method.

  An application might use theactiveCountmethod to get an estimate of how big the array should be, howeverif the array is too short to hold all the threads, the extra threadsare silently ignored. If it is critical to obtain every livethread in the current thread's thread group and its subgroups, theinvoker should verify that the returned int value is strictly lessthan the length oftarray.

  Due to the inherent race condition in this method, it is recommendedthat the method only be used for debugging and monitoring purposes.

  Parameters:

  tarray - an array into which to put the list of threads

  Returns:

  the number of threads put into the array

• join

  public final void join(long millis) throwsInterruptedException

  Waits at mostmillis milliseconds for this thread to terminate.A timeout of0 means to wait forever.This method returns immediately, without waiting, if the thread has notbeenstarted.

  Implementation Note:

  For platform threads, the implementation uses a loop ofthis.waitcalls conditioned onthis.isAlive. As a thread terminates thethis.notifyAll method is invoked. It is recommended thatapplications not usewait,notify, ornotifyAll onThread instances.

  Parameters:

  millis - the time to wait in milliseconds

  Throws:

  IllegalArgumentException - if the value ofmillis is negative

  InterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.

• join

  public final void join(long millis, int nanos) throwsInterruptedException

  Waits at mostmillis milliseconds plusnanos nanoseconds for this thread to terminate.If both arguments are0, it means to wait forever.This method returns immediately, without waiting, if the thread has notbeenstarted.

  Implementation Note:

  For platform threads, the implementation uses a loop ofthis.waitcalls conditioned onthis.isAlive. As a thread terminates thethis.notifyAll method is invoked. It is recommended thatapplications not usewait,notify, ornotifyAll onThread instances.

  Parameters:

  millis - the time to wait in milliseconds

  nanos -0-999999 additional nanoseconds to wait

  Throws:

  IllegalArgumentException - if the value ofmillis is negative, or the value ofnanos is not in the range0-999999

  InterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.

• join

  public final void join() throwsInterruptedException

  Waits for this thread to terminate.

  An invocation of this method behaves in exactly the sameway as the invocation

  join(0)

  Throws:

  InterruptedException - if any thread has interrupted the current thread. Theinterrupted status of the current thread is cleared when this exception is thrown.

• join

  public final boolean join(Duration duration) throwsInterruptedException

  Waits for this thread to terminate for up to the given waiting duration.

  This method does not wait if the duration to wait is less than orequal to zero. In this case, the method just tests if the thread hasterminated.

  Parameters:

  duration - the maximum duration to wait

  Returns:

  true if the thread has terminated,false if the thread has not terminated

  Throws:

  InterruptedException - if the current thread is interrupted while waiting. Theinterrupted status of the current thread is cleared when this exception is thrown.

  IllegalThreadStateException - if this thread has not been started.

  Since:

  19

• dumpStack

  public static void dumpStack()

  Prints a stack trace of the current thread to the standard error stream.This method is useful for debugging.

• setDaemon

  public final void setDaemon(boolean on)

  Marks this thread as either adaemon ornon-daemon thread.Theshutdown sequence begins when allstarted non-daemon threads have terminated.

  The daemon status of a virtual thread is alwaystrue and cannot bechanged by this method tofalse.

  This method must be invoked before the thread is started. The behaviorof this method when the thread has terminated is not specified.

  Parameters:

  on - iftrue, marks this thread as a daemon thread

  Throws:

  IllegalArgumentException - if this is a virtual thread andon is false

  IllegalThreadStateException - if this thread isalive

• isDaemon

  public final boolean isDaemon()

  Tests if this thread is a daemon thread.The daemon status of a virtual thread is alwaystrue.

  Returns:

  true if this thread is a daemon thread;false otherwise.

  See Also:

  • setDaemon(boolean)

• checkAccess

  @Deprecated(since="17",forRemoval=true)public final void checkAccess()

  Deprecated, for removal: This API element is subject to removal in a future version.

  This method originally determined if the currently runningthread had permission to modify this thread. This method was only usefulin conjunction withthe Security Manager,which is no longer supported. There is no replacement for the SecurityManager or this method.

  Does nothing.

• toString

  public String toString()

  Returns a string representation of this thread. The string representationwill usually include the thread'sidentifier andname. The default implementation for platform threads includes the thread'sidentifier, name, priority, and the name of the thread group.

  Overrides:

  toString in class Object

  Returns:

  a string representation of this thread.

• getContextClassLoader

  public ClassLoader getContextClassLoader()

  Returns the contextClassLoader for this thread.The contextClassLoader may be set by the creator of the threadfor use by code running in this thread when loading classes and resources.If notset, the default is to inheritthe context class loader from the parent thread.

  The contextClassLoader of the primordial thread is typicallyset to the class loader used to load the application.

  Returns:

  the contextClassLoader for this thread, ornull indicating the system class loader (or, failing that, the bootstrap class loader)

  Since:

  1.2

• setContextClassLoader

  public void setContextClassLoader(ClassLoader cl)

  Sets the contextClassLoader for this thread.

  The contextClassLoader may be set by the creator of the threadfor use by code running in this thread when loading classes and resources.

  Parameters:

  cl - the context ClassLoader for this Thread, or null indicating the system class loader (or, failing that, the bootstrap class loader)

  Since:

  1.2

• holdsLock

  public static boolean holdsLock(Object obj)

  Returnstrue if and only if the current thread holds themonitor lock on the specified object.

  This method is designed to allow a program to assert thatthe current thread already holds a specified lock:

      assert Thread.holdsLock(obj);

  Parameters:

  obj - the object on which to test lock ownership

  Returns:

  true if the current thread holds the monitor lock on the specified object.

  Since:

  1.4

• getStackTrace

  public StackTraceElement[] getStackTrace()

  Returns an array of stack trace elements representing the stack dumpof this thread. This method will return a zero-length array ifthis thread has not started, has started but has not yet beenscheduled to run by the system, or has terminated.If the returned array is of non-zero length then the first element ofthe array represents the top of the stack, which is the most recentmethod invocation in the sequence. The last element of the arrayrepresents the bottom of the stack, which is the least recent methodinvocation in the sequence.

  Some virtual machines may, under some circumstances, omit oneor more stack frames from the stack trace. In the extreme case,a virtual machine that has no stack trace information concerningthis thread is permitted to return a zero-length array from thismethod.

  Returns:

  an array ofStackTraceElement,each represents one stack frame.

  Since:

  1.5

  See Also:

  • Throwable.getStackTrace()

• getAllStackTraces

  public static Map<Thread,StackTraceElement[]> getAllStackTraces()

  Returns a map of stack traces for all live platform threads. The mapdoes not include virtual threads.The map keys are threads and each map value is an array ofStackTraceElement that represents the stack dumpof the correspondingThread.The returned stack traces are in the format specified forthegetStackTrace method.

  The threads may be executing while this method is called.The stack trace of each thread only represents a snapshot andeach stack trace may be obtained at different time. A zero-lengtharray will be returned in the map value if the virtual machine hasno stack trace information about a thread.

  Returns:

  aMap fromThread to an array ofStackTraceElement that represents the stack trace ofthe corresponding thread.

  Since:

  1.5

  See Also:

  • getStackTrace()
  • Throwable.getStackTrace()

• getId

  @Deprecated(since="19")public long getId()

  Deprecated.

  This method is not final and may be overridden to return avalue that is not the thread ID. UsethreadId() instead.

  Returns the identifier of this Thread. The thread ID is a positivelong number generated when this thread was created.The thread ID is unique and remains unchanged during its lifetime.

  Returns:

  this thread's ID

  Since:

  1.5

• threadId

  public final long threadId()

  Returns the identifier of this Thread. The thread ID is a positivelong number generated when this thread was created.The thread ID is unique and remains unchanged during its lifetime.

  Returns:

  this thread's ID

  Since:

  19

• getState

  public Thread.State getState()

  Returns the state of this thread.This method is designed for use in monitoring of the system state,not for synchronization control.

  Returns:

  this thread's state.

  Since:

  1.5

• setDefaultUncaughtExceptionHandler

  public static void setDefaultUncaughtExceptionHandler(Thread.UncaughtExceptionHandler ueh)

  Set the default handler invoked when a thread abruptly terminatesdue to an uncaught exception, and no other handler has been definedfor that thread.

  Uncaught exception handling is controlled first by the thread, thenby the thread'sThreadGroup object and finally by the defaultuncaught exception handler. If the thread does not have an explicituncaught 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 applicationcan change the way in which uncaught exceptions are handled (such aslogging to a specific device, or file) for those threads that wouldalready accept whatever "default" behavior the systemprovided.

  Note that the default uncaught exception handler should not usuallydefer to the thread'sThreadGroup object, as that could causeinfinite recursion.

  Parameters:

  ueh - the object to use as the default uncaught exception handler.Ifnull then there is no default handler.

  Since:

  1.5

  See Also:

  • setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler)
  • getUncaughtExceptionHandler()
  • ThreadGroup.uncaughtException(Thread, Throwable)

• getDefaultUncaughtExceptionHandler

  public static Thread.UncaughtExceptionHandler getDefaultUncaughtExceptionHandler()

  Returns the default handler invoked when a thread abruptly terminatesdue to an uncaught exception. If the returned value isnull,there is no default.

  Returns:

  the default uncaught exception handler for all threads

  Since:

  1.5

  See Also:

  • setDefaultUncaughtExceptionHandler(Thread.UncaughtExceptionHandler)

• getUncaughtExceptionHandler

  public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler()

  Returns the handler invoked when this thread abruptly terminatesdue to an uncaught exception. If this thread has not had anuncaught exception handler explicitly set then this thread'sThreadGroup object is returned, unless this threadhas terminated, in which casenull is returned.

  Returns:

  the uncaught exception handler for this thread

  Since:

  1.5

• setUncaughtExceptionHandler

  public void setUncaughtExceptionHandler(Thread.UncaughtExceptionHandler ueh)

  Set the handler invoked when this thread abruptly terminatesdue to an uncaught exception.

  A thread can take full control of how it responds to uncaughtexceptions by having its uncaught exception handler explicitly set.If no such handler is set then the thread'sThreadGroupobject acts as its handler.

  Parameters:

  ueh - the object to use as this thread's uncaught exceptionhandler. Ifnull then this thread has no explicit handler.

  Since:

  1.5

  See Also:

  • setDefaultUncaughtExceptionHandler(Thread.UncaughtExceptionHandler)
  • ThreadGroup.uncaughtException(Thread, Throwable)