The public interface object used to interact with a
ContentProvider. This is obtained by
acquireContentProviderClient(Uri). This object must be released
release() in order to indicate to the system that the
no longer needed and can be killed to free up resources.
Note that you should generally create a new ContentProviderClient instance
for each thread that will be performing operations. Unlike
ContentResolver, the methods here such as
query(Uri, String, String, String, String) and
openFile(Uri, String) are not thread safe -- you must not call
release() on the ContentProviderClient those calls are made from
until you are finished with the data they have returned.
Get a reference to the
Invoked when the garbage collector has detected that this instance is no longer reachable.
Get a reference to the
ContentProvider that is associated with this
client. If the
ContentProvider is running in a different process then
null will be returned. This can be used if you know you are running in the same
process as a provider, and want to get direct access to its implementation details.
ContentProvideris local, returns it. Otherwise returns null.
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
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
Uncaught exceptions thrown by finalizers are ignored and do not terminate the finalizer thread. See Effective Java Item 7, "Avoid finalizers" for more.