public abstract class UEventObserver extends Object
Subclass UEventObserver, implementing onUEvent(UEvent event), then call startObserving() with a match string. The UEvent thread will then call your onUEvent() method when a UEvent occurs that contains your match string.
Call stopObserving() to stop receiving UEvent's.
There is only one UEvent thread per process, even if that process has multiple UEventObserver subclass instances. The UEvent thread starts when the startObserving() is called for the first time in that process. Once started the UEvent thread will not stop (although it can stop notifying UEventObserver's via stopObserving()).
| Modifier and Type | Class and Description |
|---|---|
static class |
UEventObserver.UEvent
Representation of a UEvent.
|
| Constructor and Description |
|---|
UEventObserver() |
| Modifier and Type | Method and Description |
|---|---|
protected void |
finalize()
Invoked when the garbage collector has detected that this instance is no longer reachable.
|
abstract void |
onUEvent(UEventObserver.UEvent event)
Subclasses of UEventObserver should override this method to handle
UEvents.
|
void |
startObserving(String match)
Begin observation of UEvent's.
|
void |
stopObserving()
End observation of UEvent's.
|
protected void finalize()
throws Throwable
ObjectNote 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.
public final void startObserving(String match)
This method will cause the UEvent thread to start if this is the first invocation of startObserving in this process.
Once called, the UEvent thread will call onUEvent() when an incoming UEvent matches the specified string.
This method can be called multiple times to register multiple matches. Only one call to stopObserving is required even with multiple registered matches.
match - A substring of the UEvent to match. Try to be as specific
as possible to avoid incurring unintended additional cost from processing
irrelevant messages. Netlink messages can be moderately high bandwidth and
are expensive to parse. For example, some devices may send one netlink message
for each vsync period.public final void stopObserving()
This process's UEvent thread will never call onUEvent() on this UEventObserver after this call. Repeated calls have no effect.
public abstract void onUEvent(UEventObserver.UEvent event)