| java.lang.Object | |
| ↳ | android.os.MessageQueue |
Low-level class holding the list of messages to be dispatched by a
Looper. Messages are not added directly to a MessageQueue,
but rather through Handler objects associated with the Looper.
You can retrieve the MessageQueue for the current thread with
Looper.myQueue().
| Nested Classes | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| MessageQueue.IdleHandler | Callback interface for discovering when a thread is going to block waiting for more messages. | ||||||||||
| MessageQueue.OnFileDescriptorEventListener | A listener which is invoked when file descriptor related events occur. | ||||||||||
| Public Methods | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Add a new
MessageQueue.IdleHandler to this message queue.
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Adds a file descriptor listener to receive notification when file descriptor
related events occur.
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Returns true if the looper has no pending messages which are due to be processed.
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Remove an
MessageQueue.IdleHandler from the queue that was previously added
with addIdleHandler(MessageQueue.IdleHandler).
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Removes a file descriptor listener.
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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
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Add a new MessageQueue.IdleHandler to this message queue. This may be
removed automatically for you by returning false from
IdleHandler.queueIdle() when it is
invoked, or explicitly removing it with removeIdleHandler(MessageQueue.IdleHandler).
This method is safe to call from any thread.
| handler | The IdleHandler to be added. |
|---|
Adds a file descriptor listener to receive notification when file descriptor related events occur.
If the file descriptor has already been registered, the specified events and listener will replace any that were previously associated with it. It is not possible to set more than one listener per file descriptor.
It is important to always unregister the listener when the file descriptor is no longer of use.
| fd | The file descriptor for which a listener will be registered. |
|---|---|
| events | The set of events to receive: a combination of the
EVENT_INPUT,
EVENT_OUTPUT, and
EVENT_ERROR event masks. If the requested
set of events is zero, then the listener is unregistered. |
| listener | The listener to invoke when file descriptor events occur. |
Returns true if the looper has no pending messages which are due to be processed.
This method is safe to call from any thread.
Remove an MessageQueue.IdleHandler from the queue that was previously added
with addIdleHandler(MessageQueue.IdleHandler). If the given object is not currently
in the idle list, nothing is done.
This method is safe to call from any thread.
| handler | The IdleHandler to be removed. |
|---|
Removes a file descriptor listener.
This method does nothing if no listener has been registered for the specified file descriptor.
| fd | The file descriptor whose listener will be unregistered. |
|---|
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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