HandlerThread


public class HandlerThread
extends Thread

java.lang.Object
   ↳ java.lang.Thread
     ↳ android.os.HandlerThread


A Thread that has a Looper. The Looper can then be used to create Handlers.

Note that just like with a regular Thread, Thread.start() must still be called.

Summary

Inherited constants

int MAX_PRIORITY

The maximum priority that a thread can have.

int MIN_PRIORITY

The minimum priority that a thread can have.

int NORM_PRIORITY

The default priority that is assigned to a thread.

Public constructors

HandlerThread(String name)
HandlerThread(String name, int priority)

Constructs a HandlerThread.

Public methods

Looper getLooper()

This method returns the Looper associated with this thread.

int getThreadId()

Returns the identifier of this thread.

boolean quit()

Quits the handler thread's looper.

boolean quitSafely()

Quits the handler thread's looper safely.

void run()

If this thread was constructed using a separate Runnable run object, then that Runnable object's run method is called; otherwise, this method does nothing and returns.

Protected methods

void onLooperPrepared()

Call back method that can be explicitly overridden if needed to execute some setup before Looper loops.

Inherited methods

static int activeCount()

Returns an estimate of the number of active threads in the current thread's thread group and its subgroups.

final void checkAccess()

This method was deprecated in API level Baklava. This method is only useful in conjunction with the Security Manager, which is deprecated and subject to removal in a future release. Consequently, this method is also deprecated and subject to removal. There is no replacement for the Security Manager or this method.

Object clone()

Throws CloneNotSupportedException as a Thread can not be meaningfully cloned.

static Thread currentThread()

Returns a reference to the currently executing thread object.

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.

static Map<ThreadStackTraceElement[]> getAllStackTraces()

Returns a map of stack traces for all live threads.

ClassLoader getContextClassLoader()

Returns the context ClassLoader for this thread.

static Thread.UncaughtExceptionHandler getDefaultUncaughtExceptionHandler()

Returns the default handler invoked when a thread abruptly terminates due to an uncaught exception.

long getId()

This method was deprecated in API level Baklava. This method is not final and may be overridden to return a value that is not the thread ID. Use threadId() instead.

final String getName()

Returns this thread's name.

final 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.

final 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)

Returns true 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.

final boolean isAlive()

Tests if this thread is alive.

final boolean isDaemon()

Tests if this thread is a daemon thread.

boolean isInterrupted()

Tests whether this thread has been interrupted.

final boolean isVirtual()

Returns true if this thread is a virtual thread.

final void join()

Waits for this thread to die.

final void join(long millis)

Waits at most millis milliseconds for this thread to die.

final void join(long millis, int nanos)

Waits at most millis milliseconds plus nanos nanoseconds for this thread to die.

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.

void run()

If this thread was constructed using a separate Runnable run object, then that Runnable object's run method is called; otherwise, this method does nothing and returns.

void setContextClassLoader(ClassLoader cl)

Sets the context ClassLoader for this Thread.

final void setDaemon(boolean on)

Marks this thread as either a daemon 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.

final void setName(String name)

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

final 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, 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.

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.

void start()

Causes this thread to begin execution; the Java Virtual Machine calls the run method of this thread.

final void stop()

This method was deprecated in API level 15. This method was originally designed to force a thread to stop and throw a ThreadDeath as an exception. It was 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 of stop 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), the interrupt method should be used to interrupt the wait. For more information, see Why are Thread.stop, Thread.suspend and Thread.resume Deprecated?.

final long threadId()

Returns the identifier of this Thread.

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.

Object clone()

Creates and returns a copy of this object.

boolean equals(Object obj)

Indicates whether some other object is "equal to" this one.

void finalize()

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.

final Class<?> getClass()

Returns the runtime class of this Object.

int hashCode()

Returns a hash code value for the object.

final void notify()

Wakes up a single thread that is waiting on this object's monitor.

final void notifyAll()

Wakes up all threads that are waiting on this object's monitor.

String toString()

Returns a string representation of the object.

final void wait(long timeoutMillis, int nanos)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait(long timeoutMillis)

Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

final void wait()

Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

abstract void run()

When an object implementing interface Runnable is used to create a thread, starting the thread causes the object's run method to be called in that separately executing thread.

Public constructors

HandlerThread

Added in API level 1
public HandlerThread (String name)

Parameters
name String

HandlerThread

Added in API level 1
public HandlerThread (String name, 
                int priority)

Constructs a HandlerThread.

Parameters
priority int: The priority to run the thread at. The value supplied must be from Process and not from java.lang.Thread.

Public methods

getLooper

Added in API level 1
public Looper getLooper ()

This method returns the Looper associated with this thread. If this thread not been started or for any reason isAlive() returns false, this method will return null. If this thread has been started, this method will block until the looper has been initialized.

Returns
Looper The looper.

getThreadId

Added in API level 1
public int getThreadId ()

Returns the identifier of this thread. See Process.myTid().

Returns
int

quit

Added in API level 5
public boolean quit ()

Quits the handler thread's looper.

Causes the handler thread's looper to terminate without processing any more messages in the message queue.

Any attempt to post messages to the queue after the looper is asked to quit will fail. For example, the Handler.sendMessage(Message) method will return false.

Using this method may be unsafe because some messages may not be delivered before the looper terminates. Consider using quitSafely() instead to ensure that all pending work is completed in an orderly manner.

Returns
boolean True if the looper looper has been asked to quit or false if the thread had not yet started running.

See also:

quitSafely

Added in API level 18
public boolean quitSafely ()

Quits the handler thread's looper safely.

Causes the handler thread's looper to terminate as soon as all remaining messages in the message queue that are already due to be delivered have been handled. Pending delayed messages with due times in the future will not be delivered.

Any attempt to post messages to the queue after the looper is asked to quit will fail. For example, the Handler.sendMessage(Message) method will return false.

If the thread has not been started or has finished (that is if getLooper() returns null), then false is returned. Otherwise the looper is asked to quit and true is returned.

Returns
boolean True if the looper looper has been asked to quit or false if the thread had not yet started running.

run

Added in API level 1
public void run ()

If this thread was constructed using a separate Runnable run object, then that Runnable object's run method is called; otherwise, this method does nothing and returns.

Subclasses of Thread should override this method.

Protected methods

onLooperPrepared

Added in API level 1
protected void onLooperPrepared ()

Call back method that can be explicitly overridden if needed to execute some setup before Looper loops.