Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Protected Ctors](https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#proctors) \| [Methods](https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#pubmethods) \| [Inherited Methods](https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#inhmethods)
# ReentrantReadWriteLock.WriteLock
`
public
static
class
ReentrantReadWriteLock.WriteLock
`
`
extends https://developer.android.com/reference/java/lang/Object
`
`
implements
https://developer.android.com/reference/java/util/concurrent/locks/Lock,
https://developer.android.com/reference/java/io/Serializable
`
|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) ||
| ↳ | java.util.concurrent.locks.ReentrantReadWriteLock.WriteLock |
*** ** * ** ***
The lock returned by method `https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock#writeLock()`.
## Summary
| ### Protected constructors ||
|---|---|
| ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#WriteLock(java.util.concurrent.locks.ReentrantReadWriteLock)(https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock lock) ` Constructor for use by subclasses. |
| ### Public methods ||
|---|---|
| ` int` | ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#getHoldCount()() ` Queries the number of holds on this write lock by the current thread. |
| ` boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#isHeldByCurrentThread()() ` Queries if this write lock is held by the current thread. |
| ` void` | ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#lock()() ` Acquires the write lock. |
| ` void` | ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#lockInterruptibly()() ` Acquires the write lock unless the current thread is [interrupted](https://developer.android.com/reference/java/lang/Thread#interrupt()). |
| ` https://developer.android.com/reference/java/util/concurrent/locks/Condition` | ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#newCondition()() ` Returns a `https://developer.android.com/reference/java/util/concurrent/locks/Condition` instance for use with this `https://developer.android.com/reference/java/util/concurrent/locks/Lock` instance. |
| ` https://developer.android.com/reference/java/lang/String` | ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#toString()() ` Returns a string identifying this lock, as well as its lock state. |
| ` boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#tryLock()() ` Acquires the write lock only if it is not held by another thread at the time of invocation. |
| ` boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#tryLock(long,%20java.util.concurrent.TimeUnit)(long timeout, https://developer.android.com/reference/java/util/concurrent/TimeUnit unit) ` Acquires the write lock if it is not held by another thread within the given waiting time and the current thread has not been [interrupted](https://developer.android.com/reference/java/lang/Thread#interrupt()). |
| ` void` | ` https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#unlock()() ` Attempts to release this lock. |
| ### Inherited methods |
|---|---|
| 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*. | ||
| From interface ` https://developer.android.com/reference/java/util/concurrent/locks/Lock ` |---|---| | ` abstract void` | ` https://developer.android.com/reference/java/util/concurrent/locks/Lock#lock()() ` Acquires the lock. | | ` abstract void` | ` https://developer.android.com/reference/java/util/concurrent/locks/Lock#lockInterruptibly()() ` Acquires the lock unless the current thread is [interrupted](https://developer.android.com/reference/java/lang/Thread#interrupt()). | | ` abstract https://developer.android.com/reference/java/util/concurrent/locks/Condition` | ` https://developer.android.com/reference/java/util/concurrent/locks/Lock#newCondition()() ` Returns a new `https://developer.android.com/reference/java/util/concurrent/locks/Condition` instance that is bound to this `Lock` instance. | | ` abstract boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/Lock#tryLock()() ` Acquires the lock only if it is free at the time of invocation. | | ` abstract boolean` | ` https://developer.android.com/reference/java/util/concurrent/locks/Lock#tryLock(long,%20java.util.concurrent.TimeUnit)(long time, https://developer.android.com/reference/java/util/concurrent/TimeUnit unit) ` Acquires the lock if it is free within the given waiting time and the current thread has not been [interrupted](https://developer.android.com/reference/java/lang/Thread#interrupt()). | | ` abstract void` | ` https://developer.android.com/reference/java/util/concurrent/locks/Lock#unlock()() ` Releases the lock. | ||
## Protected constructors
### WriteLock
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
protected WriteLock (ReentrantReadWriteLock lock)
```
Constructor for use by subclasses.
| Parameters ||
|---|---|
| `lock` | `ReentrantReadWriteLock`: the outer lock object
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the lock is null |
## Public methods
### getHoldCount
Added in [API level 9](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public int getHoldCount ()
```
Queries the number of holds on this write lock by the current
thread. A thread has a hold on a lock for each lock action
that is not matched by an unlock action. Identical in effect
to `https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock#getWriteHoldCount()`.
| Returns ||
|---|---|
| `int` | the number of holds on this lock by the current thread, or zero if this lock is not held by the current thread
|
### isHeldByCurrentThread
Added in [API level 9](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean isHeldByCurrentThread ()
```
Queries if this write lock is held by the current thread.
Identical in effect to `https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock#isWriteLockedByCurrentThread()`.
| Returns ||
|---|---|
| `boolean` | `true` if the current thread holds this lock and `false` otherwise
|
### lock
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void lock ()
```
Acquires the write lock.
Acquires the write lock if neither the read nor write lock
are held by another thread
and returns immediately, setting the write lock hold count to
one.
If the current thread already holds the write lock then the
hold count is incremented by one and the method returns
immediately.
If the lock is held by another thread then the current
thread becomes disabled for thread scheduling purposes and
lies dormant until the write lock has been acquired, at which
time the write lock hold count is set to one.
### lockInterruptibly
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void lockInterruptibly ()
```
Acquires the write lock unless the current thread is
[interrupted](https://developer.android.com/reference/java/lang/Thread#interrupt()).
Acquires the write lock if neither the read nor write lock
are held by another thread
and returns immediately, setting the write lock hold count to
one.
If the current thread already holds this lock then the
hold count is incremented by one and the method returns
immediately.
If the lock is held by another thread then the current
thread becomes disabled for thread scheduling purposes and
lies dormant until one of two things happens:
- The write lock is acquired by the current thread; or
- Some other thread [interrupts](https://developer.android.com/reference/java/lang/Thread#interrupt()) the current thread.
If the write lock is acquired by the current thread then the
lock hold count is set to one.
If the current thread:
- has its interrupted status set on entry to this method; or
- is [interrupted](https://developer.android.com/reference/java/lang/Thread#interrupt()) while acquiring the write lock,
then `https://developer.android.com/reference/java/lang/InterruptedException` is thrown and the current thread's interrupted status is cleared.
In this implementation, as this method is an explicit
interruption point, preference is given to responding to
the interrupt over normal or reentrant acquisition of the
lock.
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/InterruptedException` | if the current thread is interrupted |
### newCondition
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public Condition newCondition ()
```
Returns a `https://developer.android.com/reference/java/util/concurrent/locks/Condition` instance for use with this
`https://developer.android.com/reference/java/util/concurrent/locks/Lock` instance.
The returned `https://developer.android.com/reference/java/util/concurrent/locks/Condition` instance supports the same
usages as do the `https://developer.android.com/reference/java/lang/Object` monitor methods (`https://developer.android.com/reference/java/lang/Object#wait()`, `https://developer.android.com/reference/java/lang/Object#notify()`, and `https://developer.android.com/reference/java/lang/Object#notifyAll()`) when used with the built-in
monitor lock.
- If this write lock is not held when any `https://developer.android.com/reference/java/util/concurrent/locks/Condition` method is called then an `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` is thrown. (Read locks are held independently of write locks, so are not checked or affected. However it is essentially always an error to invoke a condition waiting method when the current thread has also acquired read locks, since other threads that could unblock it will not be able to acquire the write lock.)
- When the condition [waiting](https://developer.android.com/reference/java/util/concurrent/locks/Condition#await()) methods are called the write lock is released and, before they return, the write lock is reacquired and the lock hold count restored to what it was when the method was called.
- If a thread is [interrupted](https://developer.android.com/reference/java/lang/Thread#interrupt()) while waiting then the wait will terminate, an `https://developer.android.com/reference/java/lang/InterruptedException` will be thrown, and the thread's interrupted status will be cleared.
- Waiting threads are signalled in FIFO order.
- The ordering of lock reacquisition for threads returning from waiting methods is the same as for threads initially acquiring the lock, which is in the default case not specified, but for *fair* locks favors those threads that have been waiting the longest.
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/util/concurrent/locks/Condition` | the Condition object
|
### 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 lock, as well as its lock
state. The state, in brackets includes either the String
`"Unlocked"` or the String `"Locked by"`
followed by the [name](https://developer.android.com/reference/java/lang/Thread#getName()) of the owning thread.
| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/String` | a string identifying this lock, as well as its lock state
|
### tryLock
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean tryLock ()
```
Acquires the write lock only if it is not held by another thread
at the time of invocation.
Acquires the write lock if neither the read nor write lock
are held by another thread
and returns immediately with the value `true`,
setting the write lock hold count to one. Even when this lock has
been set to use a fair ordering policy, a call to
`tryLock()` *will* immediately acquire the
lock if it is available, whether or not other threads are
currently waiting for the write lock. This "barging"
behavior can be useful in certain circumstances, even
though it breaks fairness. If you want to honor the
fairness setting for this lock, then use `https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#tryLock(long,%20java.util.concurrent.TimeUnit)`
which is almost equivalent (it also detects interruption).
If the current thread already holds this lock then the
hold count is incremented by one and the method returns
`true`.
If the lock is held by another thread then this method
will return immediately with the value `false`.
| Returns ||
|---|---|
| `boolean` | `true` if the lock was free and was acquired by the current thread, or the write lock was already held by the current thread; and `false` otherwise.
|
### tryLock
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public boolean tryLock (long timeout,
TimeUnit unit)
```
Acquires the write lock if it is not held by another thread
within the given waiting time and the current thread has
not been [interrupted](https://developer.android.com/reference/java/lang/Thread#interrupt()).
Acquires the write lock if neither the read nor write lock
are held by another thread
and returns immediately with the value `true`,
setting the write lock hold count to one. If this lock has been
set to use a fair ordering policy then an available lock
*will not* be acquired if any other threads are
waiting for the write lock. This is in contrast to the `https://developer.android.com/reference/java/util/concurrent/locks/ReentrantReadWriteLock.WriteLock#tryLock()` method. If you want a timed `tryLock`
that does permit barging on a fair lock then combine the
timed and un-timed forms together:
if (lock.tryLock() ||
lock.tryLock(timeout, unit)) {
...
}
If the current thread already holds this lock then the
hold count is incremented by one and the method returns
`true`.
If the lock is held by another thread then the current
thread becomes disabled for thread scheduling purposes and
lies dormant until one of three things happens:
- The write lock is acquired by the current thread; or
- Some other thread [interrupts](https://developer.android.com/reference/java/lang/Thread#interrupt()) the current thread; or
- The specified waiting time elapses
If the write lock is acquired then the value `true` is
returned and the write lock hold count is set to one.
If the current thread:
- has its interrupted status set on entry to this method; or
- is [interrupted](https://developer.android.com/reference/java/lang/Thread#interrupt()) while acquiring the write lock,
then `https://developer.android.com/reference/java/lang/InterruptedException` is thrown and the current thread's interrupted status is cleared.
If the specified waiting time elapses then the value
`false` is returned. If the time is less than or
equal to zero, the method will not wait at all.
In this implementation, as this method is an explicit
interruption point, preference is given to responding to
the interrupt over normal or reentrant acquisition of the
lock, and over reporting the elapse of the waiting time.
| Parameters ||
|---|---|
| `timeout` | `long`: the time to wait for the write lock
|
| `unit` | `TimeUnit`: the time unit of the timeout argument
|
| Returns ||
|---|---|
| `boolean` | `true` if the lock was free and was acquired by the current thread, or the write lock was already held by the current thread; and `false` if the waiting time elapsed before the lock could be acquired.
|
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/InterruptedException` | if the current thread is interrupted |
| `https://developer.android.com/reference/java/lang/NullPointerException` | if the time unit is null |
### unlock
Added in [API level 1](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)
```
public void unlock ()
```
Attempts to release this lock.
If the current thread is the holder of this lock then
the hold count is decremented. If the hold count is now
zero then the lock is released. If the current thread is
not the holder of this lock then `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` is thrown.
| Throws ||
|---|---|
| `https://developer.android.com/reference/java/lang/IllegalMonitorStateException` | if the current thread does not hold this lock |