public
final
class
MessageQueue
extends Object
| 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 | |
|---|---|
interface |
MessageQueue.IdleHandler
Callback interface for discovering when a thread is going to block waiting for more messages. |
interface |
MessageQueue.OnFileDescriptorEventListener
A listener which is invoked when file descriptor related events occur. |
Public methods | |
|---|---|
void
|
addIdleHandler(MessageQueue.IdleHandler handler)
Add a new |
void
|
addOnFileDescriptorEventListener(FileDescriptor fd, int events, MessageQueue.OnFileDescriptorEventListener listener)
Adds a file descriptor listener to receive notification when file descriptor related events occur. |
boolean
|
isIdle()
Returns true if the looper has no pending messages which are due to be processed. |
void
|
removeIdleHandler(MessageQueue.IdleHandler handler)
Remove an |
void
|
removeOnFileDescriptorEventListener(FileDescriptor fd)
Removes a file descriptor listener. |
Protected methods | |
|---|---|
void
|
finalize()
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. |
Inherited methods | |
|---|---|
 From
class
java.lang.Object
| |
void addIdleHandler (MessageQueue.IdleHandler handler)
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.
| Parameters | |
|---|---|
handler |
MessageQueue.IdleHandler:
The IdleHandler to be added.
|
void addOnFileDescriptorEventListener (FileDescriptor fd, int events, MessageQueue.OnFileDescriptorEventListener listener)
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.
| Parameters | |
|---|---|
fd |
FileDescriptor:
The file descriptor for which a listener will be registered. |
events |
int:
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 |
MessageQueue.OnFileDescriptorEventListener:
The listener to invoke when file descriptor events occur. |
boolean isIdle ()
Returns true if the looper has no pending messages which are due to be processed.
This method is safe to call from any thread.
| Returns | |
|---|---|
boolean |
True if the looper is idle. |
void removeIdleHandler (MessageQueue.IdleHandler handler)
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.
| Parameters | |
|---|---|
handler |
MessageQueue.IdleHandler:
The IdleHandler to be removed.
|
void removeOnFileDescriptorEventListener (FileDescriptor fd)
Removes a file descriptor listener.
This method does nothing if no listener has been registered for the specified file descriptor.
| Parameters | |
|---|---|
fd |
FileDescriptor:
The file descriptor whose listener will be unregistered. |
void finalize ()
Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
A subclass overrides the finalize method to dispose of
system resources or to perform other cleanup.
The general contract of finalize is that it is invoked
if and when the JavaTM virtual
machine has determined that there is no longer any
means by which this object can be accessed by any thread that has
not yet died, except as a result of an action taken by the
finalization of some other object or class which is ready to be
finalized. The finalize method may take any action, including
making this object available again to other threads; the usual purpose
of finalize, however, is to perform cleanup actions before
the object is irrevocably discarded. For example, the finalize method
for an object that represents an input/output connection might perform
explicit I/O transactions to break the connection before the object is
permanently discarded.
The finalize method of class Object performs no
special action; it simply returns normally. Subclasses of
Object may override this definition.
The Java programming language does not guarantee which thread will
invoke the finalize method for any given object. It is
guaranteed, however, that the thread that invokes finalize will not
be holding any user-visible synchronization locks when finalize is
invoked. If an uncaught exception is thrown by the finalize method,
the exception is ignored and finalization of that object terminates.
After the finalize method has been invoked for an object, no
further action is taken until the Java virtual machine has again
determined that there is no longer any means by which this object can
be accessed by any thread that has not yet died, including possible
actions by other objects or classes which are ready to be finalized,
at which point the object may be discarded.
The finalize method is never invoked more than once by a Java
virtual machine for any given object.
Any exception thrown by the finalize method causes
the finalization of this object to be halted, but is otherwise
ignored.
| Throws | |
|---|---|
Throwable |
|
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