|Constructor and Description|
Construct a helper for backing up / restoring the files at the given absolute locations within the file system.
|Modifier and Type||Method and Description|
Invoked when the garbage collector has detected that this instance is no longer reachable.
Based on oldState, determine which of the files from the application's data directory need to be backed up, write them to the data stream, and fill in newState with the state as it exists now.
Restore one absolute file entity from the restore stream
clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
public void performBackup(ParcelFileDescriptor oldState, BackupDataOutput data, ParcelFileDescriptor newState)
oldState- An open, read-only
ParcelFileDescriptorpointing to the last backup state provided by the application. May be
null, in which case no prior state is being provided and the application should perform a full backup.
data- An open, read/write
BackupDataOutputpointing to the backup data destination. Typically the application will use backup helper classes to write to this file.
newState- An open, read/write
ParcelFileDescriptorpointing to an empty file. The application should record the final backup state here after writing the requested data to the
public void restoreEntity(BackupDataInputStream data)
protected void finalize() throws Throwable
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.
public void writeNewStateDescription(ParcelFileDescriptor fd)