public static final class SharedObject.Reference<T extends SharedObject> extends Object implements Cloneable
| Modifier and Type | Method and Description |
|---|---|
void |
clear() |
SharedObject.Reference<T> |
clone()
Creates and returns a copy of this
Object. |
T |
copyOnWrite()
Returns a writable version of the reference.
|
protected void |
finalize()
Invoked when the garbage collector has detected that this instance is no longer reachable.
|
T |
readOnly() |
public Reference(T r)
public SharedObject.Reference<T> clone()
ObjectObject. The default
implementation returns a so-called "shallow" copy: It creates a new
instance of the same class and then copies the field values (including
object references) from this instance to the new instance. A "deep" copy,
in contrast, would also recursively clone nested objects. A subclass that
needs to implement this kind of cloning should call super.clone()
to create the new instance and then create deep copies of the nested,
mutable objects.public T readOnly()
public T copyOnWrite()
public void clear()
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.