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Android APIs
public class

PowerManager.WakeLock

extends Object
java.lang.Object
   ↳ android.os.PowerManager.WakeLock

Class Overview

Class lets you say that you need to have the device on.

Call release when you are done and don't need the lock anymore.

Any application using a WakeLock must request the android.permission.WAKE_LOCK permission in an <uses-permission> element of the application's manifest.

Summary

Public Methods
void acquire()
Makes sure the device is on at the level you asked when you created the wake lock.
void acquire(long timeout)
Makes sure the device is on at the level you asked when you created the wake lock.
boolean isHeld()
void release()
Release your claim to the CPU or screen being on.
void setReferenceCounted(boolean value)
Sets whether this WakeLock is ref counted.
void setWorkSource(WorkSource ws)
String toString()
Returns a string containing a concise, human-readable description of this object.
Protected Methods
void finalize()
Invoked when the garbage collector has detected that this instance is no longer reachable.
[Expand]
Inherited Methods
From class java.lang.Object

Public Methods

public void acquire ()

Since: API Level 1

Makes sure the device is on at the level you asked when you created the wake lock.

public void acquire (long timeout)

Since: API Level 1

Makes sure the device is on at the level you asked when you created the wake lock. The lock will be released after the given timeout.

Parameters
timeout Release the lock after the give timeout in milliseconds.

public boolean isHeld ()

Since: API Level 1

public void release ()

Since: API Level 1

Release your claim to the CPU or screen being on.

It may turn off shortly after you release it, or it may not if there are other wake locks held.

public void setReferenceCounted (boolean value)

Since: API Level 1

Sets whether this WakeLock is ref counted.

Wake locks are reference counted by default.

Parameters
value true for ref counted, false for not ref counted.

public void setWorkSource (WorkSource ws)

Since: API Level 9

public String toString ()

Since: API Level 1

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.

Returns
  • a printable representation of this object.

Protected Methods

protected void finalize ()

Since: API Level 1

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.

Throws
Throwable