java.lang.Object | |
↳ | android.net.wifi.WifiManager.MulticastLock |
Allows an application to receive Wifi Multicast packets. Normally the Wifi stack filters out packets not explicitly addressed to this device. Acquring a MulticastLock will cause the stack to receive packets addressed to multicast addresses. Processing these extra packets can cause a noticable battery drain and should be disabled when not needed.
Public Methods | |||||||||||
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Locks Wifi Multicast on until
release() is called. | |||||||||||
Checks whether this MulticastLock is currently held.
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Unlocks Wifi Multicast, restoring the filter of packets
not addressed specifically to this device and saving power.
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Controls whether this is a reference-counted or non-reference-
counted MulticastLock.
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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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Inherited Methods | |||||||||||
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From class
java.lang.Object
|
Locks Wifi Multicast on until release()
is called.
If this MulticastLock is reference-counted each call to
acquire
will increment the reference count, and the
wifi interface will receive multicast packets as long as the
reference count is above zero.
If this MulticastLock is not reference-counted, the first call to
acquire
will turn on the multicast packets, but subsequent
calls will be ignored. Only one call to release()
will
be required, regardless of the number of times that acquire
is called.
Note that other applications may also lock Wifi Multicast on.
Only they can relinquish their lock.
Also note that applications cannot leave Multicast locked on.
When an app exits or crashes, any Multicast locks will be released.
Checks whether this MulticastLock is currently held.
Unlocks Wifi Multicast, restoring the filter of packets
not addressed specifically to this device and saving power.
If this MulticastLock is reference-counted, each call to
release
will decrement the reference count, and the
multicast packets will only stop being received 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 MulticastLock is not reference-counted, the first call to
release
(after the radio was multicast locked using
acquire()
) will unlock the multicast, and subsequent calls
will be ignored.
Note that if any other Wifi Multicast Locks are still outstanding
this release
call will not have an immediate effect. Only
when all applications have released all their Multicast Locks will
the Multicast filter be turned back on.
Also note that when an app exits or crashes all of its Multicast
Locks will be automatically released.
Controls whether this is a reference-counted or non-reference-
counted MulticastLock.
Reference-counted MulticastLocks keep track of the number of calls
to acquire()
and release()
, and only stop the
reception of multicast packets when every call to acquire()
has been balanced with a call to release()
. Non-reference-
counted MulticastLocks allow the reception of multicast packets
whenever acquire()
is called and stop accepting multicast
packets whenever release()
is called.
refCounted | true if this MulticastLock 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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