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 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.

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

  See Also:

  • Inheritance when creating threads

• Thread

  public Thread(Runnable task)

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

  For a non-null group and task, invoking this constructor directly is equivalent 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 same effect asThread(null, null, name).

  This constructor is only useful when extendingThread to override 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 same effect asThread(group, null, name).

  This constructor is only useful when extendingThread to override 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 same effect asThread(null, task, name).

  For a non-null task and name, invoking this constructor directly is equivalent 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 hastask as 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 of priority of the thread creating it and the maximum permitted priority 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 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.

  For a non-null group, task, and name, invoking this constructor directly is 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 hastask 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.

  For a non-null group, task, and name, invoking this constructor directly is 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 hastask as its run object, has the specifiedname as its name, belongs to the thread group referred to bygroup, has the specifiedstackSize, and inherits initial values forinheritable thread-local variables ifinheritThreadLocals istrue.

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

  Specifying a value oftrue for theinheritThreadLocals parameter 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 directly is 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 yield its current use of a processor. The scheduler is free to ignore this hint.

  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.

• sleep

  public static void sleep(long millis) throwsInterruptedException

  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. The thread does 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 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. The thread does not lose ownership of any monitors.

  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 cease execution) for the specified duration, subject to the precision and accuracy of system timers and schedulers. This method is a no-op if the 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 the occurrence of one or more actions on the part of other activities. By invoking 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 invoking spin-wait loop constructions.

  API Note:

  As an example consider a method in a class that spins in a loop until some flag is set outside of that method. A call to theonSpinWait method 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 theonSpinWait method was not called at all. However on some architectures the Java Virtual Machine may issue the processor instructions to address such code patterns in a more beneficial way.

  Since:

  9

• ofPlatform

  public static Thread.Builder.OfPlatform ofPlatform()

  Returns a builder for creating a platformThread orThreadFactory that 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 orThreadFactory that 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 meaningfully cloned. 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 thread is 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 execute independently of the current thread.

  A thread can be started at most once. In particular, a thread can not be 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 of Thread may override this method.

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

  Specified by:

  run in interface Runnable

  Implementation Requirements:

  The default implementation executes theRunnable task that theThread was created with. If the thread was created without a task then 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 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.

  Implementation Note:

  In the JDK Reference Implementation, interruption of a thread that is not alive still records that the interrupt request was made and will 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. In other words, if this method were to be called twice in succession, the second call would return false (unless the current thread were interrupted again, after the first call had cleared its interrupted status 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. Theinterrupted status 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 has been 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_PRIORITY andnewPriority 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 the current thread, and it's a platform thread that was not attached to the VM with the Java Native Interface AttachCurrentThread function, then this method will set the operating system thread name. This may be useful for debugging and troubleshooting purposes.

  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 has terminated.

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

  Returns:

  this thread's thread group ornull

• activeCount

  public static int activeCount()

  Returns an estimate of the number oflive platform 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 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.

  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 everylive platform 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 are not enumerated by this method.

  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 live 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.

  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 not beenstarted.

  Implementation Note:

  For platform threads, the 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.

  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 not beenstarted.

  Implementation Note:

  For platform threads, the 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.

  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 same way 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 or equal to zero. In this case, the method just tests if the thread has terminated.

  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 all started non-daemon threads have terminated.

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

  This method must be invoked before the thread is started. The behavior of 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 running thread had permission to modify this thread. This method was only useful in conjunction withthe Security Manager, which is no longer supported. There is no replacement for the Security Manager or this method.

  Does nothing.

• toString

  public String toString()

  Returns a string representation of this thread. The string representation will usually include the thread'sidentifier and name. The default implementation for platform threads includes the thread's identifier, 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 thread for use by code running in this thread when loading classes and resources. If notset, the default is to inherit the context class loader from the parent thread.

  The contextClassLoader of the primordial thread is typically set 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 thread for 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 the monitor lock on the specified object.

  This method is designed to allow a program to assert that the 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 dump of this thread. This method will return a zero-length array if this thread has not started, has started but has not yet been scheduled to run by the system, or has terminated. If the returned array is of non-zero length then the first element of the array represents the top of the stack, which is the most recent method invocation in the sequence. The last element of the array represents the bottom of the stack, which is the least recent method invocation in the sequence.

  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.

  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 map does not include virtual threads. The map keys are threads and each map value is an array ofStackTraceElement that represents the stack dump of the correspondingThread. The returned stack traces are in the format specified for thegetStackTrace 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.

  Returns:

  aMap fromThread to an array ofStackTraceElement that represents the stack trace of the 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 a value 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 terminates due to an uncaught exception, and no other handler has been defined for that thread.

  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.

  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(java.lang.Thread.UncaughtExceptionHandler)
  • getUncaughtExceptionHandler()
  • ThreadGroup.uncaughtException(java.lang.Thread, java.lang.Throwable)

• getDefaultUncaughtExceptionHandler

  public static Thread.UncaughtExceptionHandler getDefaultUncaughtExceptionHandler()

  Returns the default handler invoked when a thread abruptly terminates due 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(java.lang.Thread.UncaughtExceptionHandler)

• getUncaughtExceptionHandler

  public Thread.UncaughtExceptionHandler getUncaughtExceptionHandler()

  Returns the handler invoked when this thread abruptly terminates due to an uncaught exception. If this thread has not had an uncaught exception handler explicitly set then this thread'sThreadGroup object is returned, unless this thread has 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 terminates due to an uncaught exception.

  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.

  Parameters:

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

  Since:

  1.5

  See Also:

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