Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Nested Classes](https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#nestedclasses) \| [Protected Ctors](https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#proctors) \| [Methods](https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#pubmethods) \| [Protected Methods](https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#promethods) \| [Inherited Methods](https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#inhmethods)

# AbstractQueuedSynchronizer


`
public


abstract
class
AbstractQueuedSynchronizer
`


`


`

`

extends https://developer.android.com/reference/java/util/concurrent/locks/AbstractOwnableSynchronizer


`

`


implements

https://developer.android.com/reference/java/io/Serializable


`

|---|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) |||
| ↳ | [java.util.concurrent.locks.AbstractOwnableSynchronizer](https://developer.android.com/reference/java/util/concurrent/locks/AbstractOwnableSynchronizer) ||
|   | ↳ | java.util.concurrent.locks.AbstractQueuedSynchronizer |

<br />

*** ** * ** ***

Provides a framework for implementing blocking locks and related
synchronizers (semaphores, events, etc) that rely on
first-in-first-out (FIFO) wait queues. This class is designed to
be a useful basis for most kinds of synchronizers that rely on a
single atomic `int` value to represent state. Subclasses
must define the protected methods that change this state, and which
define what that state means in terms of this object being acquired
or released. Given these, the other methods in this class carry
out all queuing and blocking mechanics. Subclasses can maintain
other state fields, but only the atomically updated `int`
value manipulated using methods `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getState()`, `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#setState(int)` and `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#compareAndSetState(int,%20int)` is tracked with respect
to synchronization.

Subclasses should be defined as non-public internal helper
classes that are used to implement the synchronization properties
of their enclosing class. Class
`AbstractQueuedSynchronizer` does not implement any
synchronization interface. Instead it defines methods such as
`https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#acquireInterruptibly(int)` that can be invoked as
appropriate by concrete locks and related synchronizers to
implement their public methods.

This class supports either or both a default *exclusive*
mode and a *shared* mode. When acquired in exclusive mode,
attempted acquires by other threads cannot succeed. Shared mode
acquires by multiple threads may (but need not) succeed. This class
does not "understand" these differences except in the
mechanical sense that when a shared mode acquire succeeds, the next
waiting thread (if one exists) must also determine whether it can
acquire as well. Threads waiting in the different modes share the
same FIFO queue. Usually, implementation subclasses support only
one of these modes, but both can come into play for example in a
`https://developer.android.com/reference/java/util/concurrent/locks/ReadWriteLock`. Subclasses that support only exclusive or
only shared modes need not define the methods supporting the unused mode.

This class defines a nested `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer.ConditionObject` class that
can be used as a `https://developer.android.com/reference/java/util/concurrent/locks/Condition` implementation by subclasses
supporting exclusive mode for which method `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#isHeldExclusively()` reports whether synchronization is exclusively
held with respect to the current thread, method `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#release(int)`
invoked with the current `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getState()` value fully releases
this object, and the underlying version of `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#acquire(int)`,
given this saved state value, eventually restores this object to
its previous acquired state.
No `AbstractQueuedSynchronizer` method otherwise creates such a
condition, so if this constraint cannot be met, do not use it. The
behavior of `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer.ConditionObject` depends of course on the
semantics of its synchronizer implementation.

This class provides inspection, instrumentation, and monitoring
methods for the internal queue, as well as similar methods for
condition objects. These can be exported as desired into classes
using an `AbstractQueuedSynchronizer` for their
synchronization mechanics.

Serialization of this class stores only the underlying atomic
integer maintaining state, so deserialized objects have empty
thread queues. Typical subclasses requiring serializability will
define a `readObject` method that restores this to a known
initial state upon deserialization.

## Usage

To use this class as the basis of a synchronizer, redefine the
following methods, as applicable, by inspecting and/or modifying
the synchronization state using `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getState()`, `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#setState(int)` and/or `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#compareAndSetState(int,%20int)`:

- `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)`
- `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryRelease(int)`
- `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)`
- `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryReleaseShared(int)`
- `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#isHeldExclusively()`

Each of these methods by default throws `https://developer.android.com/reference/java/lang/UnsupportedOperationException`. Implementations of these methods must be internally thread-safe, and should in general be short and not block. Defining these methods is the *only* supported means of using this class. All other methods are declared `final` because they cannot be independently varied.

You may also find the inherited methods from `https://developer.android.com/reference/java/util/concurrent/locks/AbstractOwnableSynchronizer` useful to keep track of the thread
owning an exclusive synchronizer. You are encouraged to use them
-- this enables monitoring and diagnostic tools to assist users in
determining which threads hold locks.

Even though this class is based on an internal FIFO queue, it
does not automatically enforce FIFO acquisition policies. The core
of exclusive synchronization takes the form:

```
Acquire:
    while (!tryAcquire(arg)) {
       enqueue thread if it is not already queued;
       possibly block current thread;
    }

Release:
    if (tryRelease(arg))
       unblock the first queued thread;
```
(Shared mode is similar but may involve cascading signals.)

Because checks in acquire are invoked before
enqueuing, a newly acquiring thread may *barge* ahead of
others that are blocked and queued. However, you can, if desired,
define `tryAcquire` and/or `tryAcquireShared` to
disable barging by internally invoking one or more of the inspection
methods, thereby providing a *fair* FIFO acquisition order.
In particular, most fair synchronizers can define `tryAcquire`
to return `false` if `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#hasQueuedPredecessors()` (a method
specifically designed to be used by fair synchronizers) returns
`true`. Other variations are possible.

Throughput and scalability are generally highest for the
default barging (also known as *greedy* ,
*renouncement* , and *convoy-avoidance* ) strategy.
While this is not guaranteed to be fair or starvation-free, earlier
queued threads are allowed to recontend before later queued
threads, and each recontention has an unbiased chance to succeed
against incoming threads. Also, while acquires do not
"spin" in the usual sense, they may perform multiple
invocations of `tryAcquire` interspersed with other
computations before blocking. This gives most of the benefits of
spins when exclusive synchronization is only briefly held, without
most of the liabilities when it isn't. If so desired, you can
augment this by preceding calls to acquire methods with
"fast-path" checks, possibly prechecking `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#hasContended()`
and/or `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#hasQueuedThreads()` to only do so if the synchronizer
is likely not to be contended.

This class provides an efficient and scalable basis for
synchronization in part by specializing its range of use to
synchronizers that can rely on `int` state, acquire, and
release parameters, and an internal FIFO wait queue. When this does
not suffice, you can build synchronizers from a lower level using
`https://developer.android.com/reference/java/util/concurrent/atomic/package-summary` classes, your own custom
`https://developer.android.com/reference/java/util/Queue` classes, and `https://developer.android.com/reference/java/util/concurrent/locks/LockSupport` blocking
support.

## Usage Examples

Here is a non-reentrant mutual exclusion lock class that uses
the value zero to represent the unlocked state, and one to
represent the locked state. While a non-reentrant lock
does not strictly require recording of the current owner
thread, this class does so anyway to make usage easier to monitor.
It also supports conditions and exposes some instrumentation methods:

    class Mutex implements Lock, java.io.Serializable {

      // Our internal helper class
      private static class Sync extends AbstractQueuedSynchronizer {
        // Acquires the lock if state is zero
        public boolean tryAcquire(int acquires) {
          assert acquires == 1; // Otherwise unused
          if (compareAndSetState(0, 1)) {
            setExclusiveOwnerThread(Thread.currentThread());
            return true;
          }
          return false;
        }

        // Releases the lock by setting state to zero
        protected boolean tryRelease(int releases) {
          assert releases == 1; // Otherwise unused
          if (!isHeldExclusively())
            throw new IllegalMonitorStateException();
          setExclusiveOwnerThread(null);
          setState(0);
          return true;
        }

        // Reports whether in locked state
        public boolean isLocked() {
          return getState() != 0;
        }

        public boolean isHeldExclusively() {
          // a data race, but safe due to out-of-thin-air guarantees
          return getExclusiveOwnerThread() == Thread.currentThread();
        }

        // Provides a Condition
        public Condition newCondition() {
          return new ConditionObject();
        }

        // Deserializes properly
        private void readObject(ObjectInputStream s)
            throws IOException, ClassNotFoundException {
          s.defaultReadObject();
          setState(0); // reset to unlocked state
        }
      }

      // The sync object does all the hard work. We just forward to it.
      private final Sync sync = new Sync();

      public void lock()              { sync.acquire(1); }
      public boolean tryLock()        { return sync.tryAcquire(1); }
      public void unlock()            { sync.release(1); }
      public Condition newCondition() { return sync.newCondition(); }
      public boolean isLocked()       { return sync.isLocked(); }
      public boolean isHeldByCurrentThread() {
        return sync.isHeldExclusively();
      }
      public boolean hasQueuedThreads() {
        return sync.hasQueuedThreads();
      }
      public void lockInterruptibly() throws InterruptedException {
        sync.acquireInterruptibly(1);
      }
      public boolean tryLock(long timeout, TimeUnit unit)
          throws InterruptedException {
        return sync.tryAcquireNanos(1, unit.toNanos(timeout));
      }
    }

Here is a latch class that is like a
`https://developer.android.com/reference/java/util/concurrent/CountDownLatch`
except that it only requires a single `signal` to
fire. Because a latch is non-exclusive, it uses the `shared`
acquire and release methods.

    class BooleanLatch {

      private static class Sync extends AbstractQueuedSynchronizer {
        boolean isSignalled() { return getState() != 0; }

        protected int tryAcquireShared(int ignore) {
          return isSignalled() ? 1 : -1;
        }

        protected boolean tryReleaseShared(int ignore) {
          setState(1);
          return true;
        }
      }

      private final Sync sync = new Sync();
      public boolean isSignalled() { return sync.isSignalled(); }
      public void signal()         { sync.releaseShared(1); }
      public void await() throws InterruptedException {
        sync.acquireSharedInterruptibly(1);
      }
    }

<br />

## Summary

| ### Nested classes ||
|---|---|
| ` class` | `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer.ConditionObject` Condition implementation for a `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer` serving as the basis of a `https://developer.android.com/reference/java/util/concurrent/locks/Lock` implementation. |

| ### Protected constructors ||
|---|---|
| ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#AbstractQueuedSynchronizer()() ` Creates a new `AbstractQueuedSynchronizer` instance with initial synchronization state of zero. |

| ### Public methods ||
|---|---|
| ` final void` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#acquire(int)(int arg) ` Acquires in exclusive mode, ignoring interrupts. |
| ` final void` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#acquireInterruptibly(int)(int arg) ` Acquires in exclusive mode, aborting if interrupted. |
| ` final void` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#acquireShared(int)(int arg) ` Acquires in shared mode, ignoring interrupts. |
| ` final void` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#acquireSharedInterruptibly(int)(int arg) ` Acquires in shared mode, aborting if interrupted. |
| ` final https://developer.android.com/reference/java/util/Collection<https://developer.android.com/reference/java/lang/Thread>` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getExclusiveQueuedThreads()() ` Returns a collection containing threads that may be waiting to acquire in exclusive mode. |
| ` final https://developer.android.com/reference/java/lang/Thread` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getFirstQueuedThread()() ` Returns the first (longest-waiting) thread in the queue, or `null` if no threads are currently queued. |
| ` final int` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getQueueLength()() ` Returns an estimate of the number of threads waiting to acquire. |
| ` final https://developer.android.com/reference/java/util/Collection<https://developer.android.com/reference/java/lang/Thread>` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getQueuedThreads()() ` Returns a collection containing threads that may be waiting to acquire. |
| ` final https://developer.android.com/reference/java/util/Collection<https://developer.android.com/reference/java/lang/Thread>` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getSharedQueuedThreads()() ` Returns a collection containing threads that may be waiting to acquire in shared mode. |
| ` final int` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getWaitQueueLength(java.util.concurrent.locks.AbstractQueuedSynchronizer.ConditionObject)(https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer.ConditionObject condition) ` Returns an estimate of the number of threads waiting on the given condition associated with this synchronizer. |
| ` final https://developer.android.com/reference/java/util/Collection<https://developer.android.com/reference/java/lang/Thread>` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getWaitingThreads(java.util.concurrent.locks.AbstractQueuedSynchronizer.ConditionObject)(https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer.ConditionObject condition) ` Returns a collection containing those threads that may be waiting on the given condition associated with this synchronizer. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#hasContended()() ` Queries whether any threads have ever contended to acquire this synchronizer; that is, if an acquire method has ever blocked. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#hasQueuedPredecessors()() ` Queries whether any threads have been waiting to acquire longer than the current thread. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#hasQueuedThreads()() ` Queries whether any threads are waiting to acquire. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#hasWaiters(java.util.concurrent.locks.AbstractQueuedSynchronizer.ConditionObject)(https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer.ConditionObject condition) ` Queries whether any threads are waiting on the given condition associated with this synchronizer. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#isQueued(java.lang.Thread)(https://developer.android.com/reference/java/lang/Thread thread) ` Returns true if the given thread is currently queued. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#owns(java.util.concurrent.locks.AbstractQueuedSynchronizer.ConditionObject)(https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer.ConditionObject condition) ` Queries whether the given ConditionObject uses this synchronizer as its lock. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#release(int)(int arg) ` Releases in exclusive mode. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#releaseShared(int)(int arg) ` Releases in shared mode. |
| ` https://developer.android.com/reference/java/lang/String` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#toString()() ` Returns a string identifying this synchronizer, as well as its state. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireNanos(int,%20long)(int arg, long nanosTimeout) ` Attempts to acquire in exclusive mode, aborting if interrupted, and failing if the given timeout elapses. |
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireSharedNanos(int,%20long)(int arg, long nanosTimeout) ` Attempts to acquire in shared mode, aborting if interrupted, and failing if the given timeout elapses. |

| ### Protected methods ||
|---|---|
| ` final boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#compareAndSetState(int,%20int)(int expect, int update) ` Atomically sets synchronization state to the given updated value if the current state value equals the expected value. |
| ` final int` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getState()() ` Returns the current value of synchronization state. |
| ` boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#isHeldExclusively()() ` Returns `true` if synchronization is held exclusively with respect to the current (calling) thread. |
| ` final void` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#setState(int)(int newState) ` Sets the value of synchronization state. |
| ` boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)(int arg) ` Attempts to acquire in exclusive mode. |
| ` int` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)(int arg) ` Attempts to acquire in shared mode. |
| ` boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryRelease(int)(int arg) ` Attempts to set the state to reflect a release in exclusive mode. |
| ` boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryReleaseShared(int)(int arg) ` Attempts to set the state to reflect a release in shared mode. |

### Inherited methods

From class `

https://developer.android.com/reference/java/util/concurrent/locks/AbstractOwnableSynchronizer

` `


final

https://developer.android.com/reference/java/lang/Thread` `
https://developer.android.com/reference/java/util/concurrent/locks/AbstractOwnableSynchronizer#getExclusiveOwnerThread()()
`

Returns the thread last set by `setExclusiveOwnerThread`,
or `null` if never set.


`


final

void` `
https://developer.android.com/reference/java/util/concurrent/locks/AbstractOwnableSynchronizer#setExclusiveOwnerThread(java.lang.Thread)(https://developer.android.com/reference/java/lang/Thread thread)
`

Sets the thread that currently owns exclusive access.


From class `

https://developer.android.com/reference/java/lang/Object

` `


https://developer.android.com/reference/java/lang/Object` `
https://developer.android.com/reference/java/lang/Object#clone()()
`

Creates and returns a copy of this object.


`


boolean` `
https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)(https://developer.android.com/reference/java/lang/Object obj)
`

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


`


void` `
https://developer.android.com/reference/java/lang/Object#finalize()()
`

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


`


final

https://developer.android.com/reference/java/lang/Class<?>` `
https://developer.android.com/reference/java/lang/Object#getClass()()
`

Returns the runtime class of this `Object`.


`


int` `
https://developer.android.com/reference/java/lang/Object#hashCode()()
`

Returns a hash code value for the object.


`


final

void` `
https://developer.android.com/reference/java/lang/Object#notify()()
`

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


`


final

void` `
https://developer.android.com/reference/java/lang/Object#notifyAll()()
`

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


`


https://developer.android.com/reference/java/lang/String` `
https://developer.android.com/reference/java/lang/Object#toString()()
`

Returns a string representation of the object.


`


final

void` `
https://developer.android.com/reference/java/lang/Object#wait(long,%20int)(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` `
https://developer.android.com/reference/java/lang/Object#wait(long)(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` `
https://developer.android.com/reference/java/lang/Object#wait()()
`

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


## Protected constructors

### AbstractQueuedSynchronizer

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected AbstractQueuedSynchronizer ()
```

Creates a new `AbstractQueuedSynchronizer` instance
with initial synchronization state of zero.

<br />

## Public methods

### acquire

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final void acquire (int arg)
```

Acquires in exclusive mode, ignoring interrupts. Implemented
by invoking at least once `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)`,
returning on success. Otherwise the thread is queued, possibly
repeatedly blocking and unblocking, invoking `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)` until success. This method can be used
to implement method `https://developer.android.com/reference/java/util/concurrent/locks/Lock#lock()`.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the acquire argument. This value is conveyed to `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)` but is otherwise uninterpreted and can represent anything you like. <br /> |

### acquireInterruptibly

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final void acquireInterruptibly (int arg)
```

Acquires in exclusive mode, aborting if interrupted.
Implemented by first checking interrupt status, then invoking
at least once `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)`, returning on
success. Otherwise the thread is queued, possibly repeatedly
blocking and unblocking, invoking `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)`
until success or the thread is interrupted. This method can be
used to implement method `https://developer.android.com/reference/java/util/concurrent/locks/Lock#lockInterruptibly()`.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the acquire argument. This value is conveyed to `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)` but is otherwise uninterpreted and can represent anything you like. <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/InterruptedException` | if the current thread is interrupted |

### acquireShared

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final void acquireShared (int arg)
```

Acquires in shared mode, ignoring interrupts. Implemented by
first invoking at least once `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)`,
returning on success. Otherwise the thread is queued, possibly
repeatedly blocking and unblocking, invoking `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)` until success.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the acquire argument. This value is conveyed to `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)` but is otherwise uninterpreted and can represent anything you like. <br /> |

### acquireSharedInterruptibly

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final void acquireSharedInterruptibly (int arg)
```

Acquires in shared mode, aborting if interrupted. Implemented
by first checking interrupt status, then invoking at least once
`https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)`, returning on success. Otherwise the
thread is queued, possibly repeatedly blocking and unblocking,
invoking `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)` until success or the thread
is interrupted.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the acquire argument. This value is conveyed to `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)` but is otherwise uninterpreted and can represent anything you like. <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/InterruptedException` | if the current thread is interrupted |

### getExclusiveQueuedThreads

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final Collection<Thread> getExclusiveQueuedThreads ()
```

Returns a collection containing threads that may be waiting to
acquire in exclusive mode. This has the same properties
as `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getQueuedThreads()` except that it only returns
those threads waiting due to an exclusive acquire.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Collection<https://developer.android.com/reference/java/lang/Thread>` | the collection of threads <br /> |

### getFirstQueuedThread

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final Thread getFirstQueuedThread ()
```

Returns the first (longest-waiting) thread in the queue, or
`null` if no threads are currently queued.

In this implementation, this operation normally returns in
constant time, but may iterate upon contention if other threads are
concurrently modifying the queue.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/Thread` | the first (longest-waiting) thread in the queue, or `null` if no threads are currently queued <br /> |

### getQueueLength

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final int getQueueLength ()
```

Returns an estimate of the number of threads waiting to
acquire. The value is only an estimate because the number of
threads may change dynamically while this method traverses
internal data structures. This method is designed for use in
monitoring system state, not for synchronization control.

<br />

| Returns ||
|---|---|
| `int` | the estimated number of threads waiting to acquire <br /> |

### getQueuedThreads

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final Collection<Thread> getQueuedThreads ()
```

Returns a collection containing threads that may be waiting to
acquire. Because the actual set of threads may change
dynamically while constructing this result, the returned
collection is only a best-effort estimate. The elements of the
returned collection are in no particular order. This method is
designed to facilitate construction of subclasses that provide
more extensive monitoring facilities.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Collection<https://developer.android.com/reference/java/lang/Thread>` | the collection of threads <br /> |

### getSharedQueuedThreads

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final Collection<Thread> getSharedQueuedThreads ()
```

Returns a collection containing threads that may be waiting to
acquire in shared mode. This has the same properties
as `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getQueuedThreads()` except that it only returns
those threads waiting due to a shared acquire.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Collection<https://developer.android.com/reference/java/lang/Thread>` | the collection of threads <br /> |

### getWaitQueueLength

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final int getWaitQueueLength (AbstractQueuedSynchronizer.ConditionObject condition)
```

Returns an estimate of the number of threads waiting on the
given condition associated with this synchronizer. Note that
because timeouts and interrupts may occur at any time, the
estimate serves only as an upper bound on the actual number of
waiters. This method is designed for use in monitoring system
state, not for synchronization control.

<br />

| Parameters ||
|---|---|
| `condition` | `AbstractQueuedSynchronizer.ConditionObject`: the condition <br /> |

| Returns ||
|---|---|
| `int` | the estimated number of waiting threads <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if the given condition is not associated with this synchronizer |
| `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` | if exclusive synchronization is not held |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the condition is null |

### getWaitingThreads

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final Collection<Thread> getWaitingThreads (AbstractQueuedSynchronizer.ConditionObject condition)
```

Returns a collection containing those threads that may be
waiting on the given condition associated with this
synchronizer. Because the actual set of threads may change
dynamically while constructing this result, the returned
collection is only a best-effort estimate. The elements of the
returned collection are in no particular order.

<br />

| Parameters ||
|---|---|
| `condition` | `AbstractQueuedSynchronizer.ConditionObject`: the condition <br /> |

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/Collection<https://developer.android.com/reference/java/lang/Thread>` | the collection of threads <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if the given condition is not associated with this synchronizer |
| `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` | if exclusive synchronization is not held |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the condition is null |

### hasContended

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean hasContended ()
```

Queries whether any threads have ever contended to acquire this
synchronizer; that is, if an acquire method has ever blocked.

In this implementation, this operation returns in
constant time.

<br />

| Returns ||
|---|---|
| `boolean` | `true` if there has ever been contention <br /> |

### hasQueuedPredecessors

Added in [API level 21](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean hasQueuedPredecessors ()
```

Queries whether any threads have been waiting to acquire longer
than the current thread.

An invocation of this method is equivalent to (but may be
more efficient than):

    getFirstQueuedThread() != Thread.currentThread()
      && hasQueuedThreads()

Note that because cancellations due to interrupts and
timeouts may occur at any time, a `true` return does not
guarantee that some other thread will acquire before the current
thread. Likewise, it is possible for another thread to win a
race to enqueue after this method has returned `false`,
due to the queue being empty.

This method is designed to be used by a fair synchronizer to
avoid [barging](https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#barging).
Such a synchronizer's `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)` method should return
`false`, and its `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)` method should
return a negative value, if this method returns `true`
(unless this is a reentrant acquire). For example, the `tryAcquire` method for a fair, reentrant, exclusive mode
synchronizer might look like this:

    protected boolean tryAcquire(int arg) {
      if (isHeldExclusively()) {
        // A reentrant acquire; increment hold count
        return true;
      } else if (hasQueuedPredecessors()) {
        return false;
      } else {
        // try to acquire normally
      }
    }

<br />

<br />

| Returns ||
|---|---|
| `boolean` | `true` if there is a queued thread preceding the current thread, and `false` if the current thread is at the head of the queue or the queue is empty <br /> |

### hasQueuedThreads

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean hasQueuedThreads ()
```

Queries whether any threads are waiting to acquire. Note that
because cancellations due to interrupts and timeouts may occur
at any time, a `true` return does not guarantee that any
other thread will ever acquire.

<br />

| Returns ||
|---|---|
| `boolean` | `true` if there may be other threads waiting to acquire <br /> |

### hasWaiters

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean hasWaiters (AbstractQueuedSynchronizer.ConditionObject condition)
```

Queries whether any threads are waiting on the given condition
associated with this synchronizer. Note that because timeouts
and interrupts may occur at any time, a `true` return
does not guarantee that a future `signal` will awaken
any threads. This method is designed primarily for use in
monitoring of the system state.

<br />

| Parameters ||
|---|---|
| `condition` | `AbstractQueuedSynchronizer.ConditionObject`: the condition <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if there are any waiting threads <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalArgumentException` | if the given condition is not associated with this synchronizer |
| `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` | if exclusive synchronization is not held |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the condition is null |

### isQueued

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean isQueued (Thread thread)
```

Returns true if the given thread is currently queued.

This implementation traverses the queue to determine
presence of the given thread.

<br />

| Parameters ||
|---|---|
| `thread` | `Thread`: the thread <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if the given thread is on the queue <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the thread is null |

### owns

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean owns (AbstractQueuedSynchronizer.ConditionObject condition)
```

Queries whether the given ConditionObject
uses this synchronizer as its lock.

<br />

| Parameters ||
|---|---|
| `condition` | `AbstractQueuedSynchronizer.ConditionObject`: the condition <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if owned <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the condition is null |

### release

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean release (int arg)
```

Releases in exclusive mode. Implemented by unblocking one or
more threads if `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryRelease(int)` returns true.
This method can be used to implement method `https://developer.android.com/reference/java/util/concurrent/locks/Lock#unlock()`.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the release argument. This value is conveyed to `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryRelease(int)` but is otherwise uninterpreted and can represent anything you like. <br /> |

| Returns ||
|---|---|
| `boolean` | the value returned from `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryRelease(int)` <br /> |

### releaseShared

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean releaseShared (int arg)
```

Releases in shared mode. Implemented by unblocking one or more
threads if `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryReleaseShared(int)` returns true.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the release argument. This value is conveyed to `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryReleaseShared(int)` but is otherwise uninterpreted and can represent anything you like. <br /> |

| Returns ||
|---|---|
| `boolean` | the value returned from `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryReleaseShared(int)` <br /> |

### toString

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public String toString ()
```

Returns a string identifying this synchronizer, as well as its state.
The state, in brackets, includes the String `"State ="`
followed by the current value of `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#getState()`, and either
`"nonempty"` or `"empty"` depending on whether the
queue is empty.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/String` | a string identifying this synchronizer, as well as its state <br /> |

### tryAcquireNanos

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean tryAcquireNanos (int arg, 
                long nanosTimeout)
```

Attempts to acquire in exclusive mode, aborting if interrupted,
and failing if the given timeout elapses. Implemented by first
checking interrupt status, then invoking at least once `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)`, returning on success. Otherwise, the thread is
queued, possibly repeatedly blocking and unblocking, invoking
`https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)` until success or the thread is interrupted
or the timeout elapses. This method can be used to implement
method `https://developer.android.com/reference/java/util/concurrent/locks/Lock#tryLock(long,%20java.util.concurrent.TimeUnit)`.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the acquire argument. This value is conveyed to `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquire(int)` but is otherwise uninterpreted and can represent anything you like. <br /> |
| `nanosTimeout` | `long`: the maximum number of nanoseconds to wait <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if acquired; `false` if timed out <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/InterruptedException` | if the current thread is interrupted |

### tryAcquireSharedNanos

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public final boolean tryAcquireSharedNanos (int arg, 
                long nanosTimeout)
```

Attempts to acquire in shared mode, aborting if interrupted, and
failing if the given timeout elapses. Implemented by first
checking interrupt status, then invoking at least once `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)`, returning on success. Otherwise, the
thread is queued, possibly repeatedly blocking and unblocking,
invoking `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)` until success or the thread
is interrupted or the timeout elapses.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the acquire argument. This value is conveyed to `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer#tryAcquireShared(int)` but is otherwise uninterpreted and can represent anything you like. <br /> |
| `nanosTimeout` | `long`: the maximum number of nanoseconds to wait <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if acquired; `false` if timed out <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/InterruptedException` | if the current thread is interrupted |

## Protected methods

### compareAndSetState

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected final boolean compareAndSetState (int expect, 
                int update)
```

Atomically sets synchronization state to the given updated
value if the current state value equals the expected value.
This operation has memory semantics of a `volatile` read
and write.

<br />

| Parameters ||
|---|---|
| `expect` | `int`: the expected value <br /> |
| `update` | `int`: the new value <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if successful. False return indicates that the actual value was not equal to the expected value. <br /> |

### getState

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected final int getState ()
```

Returns the current value of synchronization state.
This operation has memory semantics of a `volatile` read.

<br />

| Returns ||
|---|---|
| `int` | current state value <br /> |

### isHeldExclusively

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected boolean isHeldExclusively ()
```

Returns `true` if synchronization is held exclusively with
respect to the current (calling) thread. This method is invoked
upon each call to a `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer.ConditionObject` method.

The default implementation throws `https://developer.android.com/reference/java/lang/UnsupportedOperationException`. This method is invoked
internally only within `https://developer.android.com/reference/java/util/concurrent/locks/AbstractQueuedSynchronizer.ConditionObject` methods, so need
not be defined if conditions are not used.

<br />

| Returns ||
|---|---|
| `boolean` | `true` if synchronization is held exclusively; `false` otherwise <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/UnsupportedOperationException` | if conditions are not supported |

### setState

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected final void setState (int newState)
```

Sets the value of synchronization state.
This operation has memory semantics of a `volatile` write.

<br />

| Parameters ||
|---|---|
| `newState` | `int`: the new state value <br /> |

### tryAcquire

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected boolean tryAcquire (int arg)
```

Attempts to acquire in exclusive mode. This method should query
if the state of the object permits it to be acquired in the
exclusive mode, and if so to acquire it.

This method is always invoked by the thread performing
acquire. If this method reports failure, the acquire method
may queue the thread, if it is not already queued, until it is
signalled by a release from some other thread. This can be used
to implement method `https://developer.android.com/reference/java/util/concurrent/locks/Lock#tryLock()`.

The default
implementation throws `https://developer.android.com/reference/java/lang/UnsupportedOperationException`.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the acquire argument. This value is always the one passed to an acquire method, or is the value saved on entry to a condition wait. The value is otherwise uninterpreted and can represent anything you like. <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if successful. Upon success, this object has been acquired. <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` | if acquiring would place this synchronizer in an illegal state. This exception must be thrown in a consistent fashion for synchronization to work correctly. |
| `https://developer.android.com/reference/java/lang/UnsupportedOperationException` | if exclusive mode is not supported |

### tryAcquireShared

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected int tryAcquireShared (int arg)
```

Attempts to acquire in shared mode. This method should query if
the state of the object permits it to be acquired in the shared
mode, and if so to acquire it.

This method is always invoked by the thread performing
acquire. If this method reports failure, the acquire method
may queue the thread, if it is not already queued, until it is
signalled by a release from some other thread.

The default implementation throws `https://developer.android.com/reference/java/lang/UnsupportedOperationException`.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the acquire argument. This value is always the one passed to an acquire method, or is the value saved on entry to a condition wait. The value is otherwise uninterpreted and can represent anything you like. <br /> |

| Returns ||
|---|---|
| `int` | a negative value on failure; zero if acquisition in shared mode succeeded but no subsequent shared-mode acquire can succeed; and a positive value if acquisition in shared mode succeeded and subsequent shared-mode acquires might also succeed, in which case a subsequent waiting thread must check availability. (Support for three different return values enables this method to be used in contexts where acquires only sometimes act exclusively.) Upon success, this object has been acquired. <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` | if acquiring would place this synchronizer in an illegal state. This exception must be thrown in a consistent fashion for synchronization to work correctly. |
| `https://developer.android.com/reference/java/lang/UnsupportedOperationException` | if shared mode is not supported |

### tryRelease

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected boolean tryRelease (int arg)
```

Attempts to set the state to reflect a release in exclusive
mode.

This method is always invoked by the thread performing release.

The default implementation throws
`https://developer.android.com/reference/java/lang/UnsupportedOperationException`.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the release argument. This value is always the one passed to a release method, or the current state value upon entry to a condition wait. The value is otherwise uninterpreted and can represent anything you like. <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if this object is now in a fully released state, so that any waiting threads may attempt to acquire; and `false` otherwise. <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` | if releasing would place this synchronizer in an illegal state. This exception must be thrown in a consistent fashion for synchronization to work correctly. |
| `https://developer.android.com/reference/java/lang/UnsupportedOperationException` | if exclusive mode is not supported |

### tryReleaseShared

Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
protected boolean tryReleaseShared (int arg)
```

Attempts to set the state to reflect a release in shared mode.

This method is always invoked by the thread performing release.

The default implementation throws
`https://developer.android.com/reference/java/lang/UnsupportedOperationException`.

<br />

| Parameters ||
|---|---|
| `arg` | `int`: the release argument. This value is always the one passed to a release method, or the current state value upon entry to a condition wait. The value is otherwise uninterpreted and can represent anything you like. <br /> |

| Returns ||
|---|---|
| `boolean` | `true` if this release of shared mode may permit a waiting acquire (shared or exclusive) to succeed; and `false` otherwise <br /> |

| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` | if releasing would place this synchronizer in an illegal state. This exception must be thrown in a consistent fashion for synchronization to work correctly. |
| `https://developer.android.com/reference/java/lang/UnsupportedOperationException` | if shared mode is not supported |