java.lang.Object | |
↳ | android.net.wifi.WifiManager.WifiLock |
Allows an application to keep the Wi-Fi radio awake. Normally the Wi-Fi radio may turn off when the user has not used the device in a while. Acquiring a WifiLock will keep the radio on until the lock is released. Multiple applications may hold WifiLocks, and the radio will only be allowed to turn off when no WifiLocks are held in any application.
Before using a WifiLock, consider carefully if your application requires Wi-Fi access, or could function over a mobile network, if available. A program that needs to download large files should hold a WifiLock to ensure that the download will complete, but a program whose network usage is occasional or low-bandwidth should not hold a WifiLock to avoid adversely affecting battery life.
Note that WifiLocks cannot override the user-level "Wi-Fi Enabled" setting, nor Airplane Mode. They simply keep the radio from turning off when Wi-Fi is already on but the device is idle.
Any application using a WifiLock must request the android.permission.WAKE_LOCK
permission in an <uses-permission>
element of the application's manifest.
Public Methods | |||||||||||
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Locks the Wi-Fi radio on until
release() is called. | |||||||||||
Checks whether this WifiLock is currently held.
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Unlocks the Wi-Fi radio, allowing it to turn off when the device is idle.
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Controls whether this is a reference-counted or non-reference-counted WifiLock.
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Returns a string containing a concise, human-readable description of this
object.
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Protected Methods | |||||||||||
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Invoked when the garbage collector has detected that this instance is no longer reachable.
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[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
|
Locks the Wi-Fi radio on until release()
is called.
If this WifiLock is reference-counted, each call to acquire
will increment the
reference count, and the radio will remain locked as long as the reference count is
above zero.
If this WifiLock is not reference-counted, the first call to acquire
will lock
the radio, but subsequent calls will be ignored. Only one call to release()
will be required, regardless of the number of times that acquire
is called.
Checks whether this WifiLock is currently held.
Unlocks the Wi-Fi radio, allowing it to turn off when the device is idle.
If this WifiLock is reference-counted, each call to release
will decrement the
reference count, and the radio will be unlocked only when the reference count reaches
zero. If the reference count goes below zero (that is, if release
is called
a greater number of times than acquire()
), an exception is thrown.
If this WifiLock is not reference-counted, the first call to release
(after
the radio was locked using acquire()
) will unlock the radio, and subsequent
calls will be ignored.
Controls whether this is a reference-counted or non-reference-counted WifiLock.
Reference-counted WifiLocks keep track of the number of calls to acquire()
and
release()
, and only allow the radio to sleep when every call to acquire()
has been balanced with a call to release()
. Non-reference-counted WifiLocks
lock the radio whenever acquire()
is called and it is unlocked, and unlock the
radio whenever release()
is called and it is locked.
refCounted | true if this WifiLock should keep a reference count |
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Returns a string containing a concise, human-readable description of this object. Subclasses are encouraged to override this method and provide an implementation that takes into account the object's type and data. The default implementation is equivalent to the following expression:
getClass().getName() + '@' + Integer.toHexString(hashCode())
See Writing a useful
toString
method
if you intend implementing your own toString
method.
Invoked when the garbage collector has detected that this instance is no longer reachable. The default implementation does nothing, but this method can be overridden to free resources.
Note that objects that override finalize
are significantly more expensive than
objects that don't. Finalizers may be run a long time after the object is no longer
reachable, depending on memory pressure, so it's a bad idea to rely on them for cleanup.
Note also that finalizers are run on a single VM-wide finalizer thread,
so doing blocking work in a finalizer is a bad idea. A finalizer is usually only necessary
for a class that has a native peer and needs to call a native method to destroy that peer.
Even then, it's better to provide an explicit close
method (and implement
Closeable
), and insist that callers manually dispose of instances. This
works well for something like files, but less well for something like a BigInteger
where typical calling code would have to deal with lots of temporaries. Unfortunately,
code that creates lots of temporaries is the worst kind of code from the point of view of
the single finalizer thread.
If you must use finalizers, consider at least providing your own
ReferenceQueue
and having your own thread process that queue.
Unlike constructors, finalizers are not automatically chained. You are responsible for
calling super.finalize()
yourself.
Uncaught exceptions thrown by finalizers are ignored and do not terminate the finalizer thread. See Effective Java Item 7, "Avoid finalizers" for more.
Throwable |
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