Suppose the garbage collector determines at a certain point in time that an object is phantom reachable. At that time it will atomically clear all phantom references to that object and all phantom references to any other phantom-reachable objects from which that object is reachable. At the same time or at some later time it will enqueue those newly-cleared phantom references that are registered with reference queues.
In order to ensure that a reclaimable object remains so, the referent of
a phantom reference may not be retrieved: The get method of a
phantom reference always returns null.
The refersTo method can be used to test
whether some object is the referent of a phantom reference.
| Access | Constructor and Description |
|---|---|
| public | PhantomReference(T
the object the new phantom reference will refer to referent, ReferenceQueue<? super T> the queue with which the reference is to be registered,
or q)null if registration is not requiredCreates a new phantom reference that refers to the given object and is registered with the given queue. |
| Modifier and Type | Method and Description |
|---|---|
| public T | |
| private native boolean | |
| pack-priv boolean |
| PhantomReference | back to summary |
|---|---|
| public PhantomReference(T referent, ReferenceQueue<? super T> q) Creates a new phantom reference that refers to the given object and is registered with the given queue. It is possible to create a phantom reference with a
| |
| get | back to summary |
|---|---|
| public T get() Overrides java. Returns this reference object's referent. Because the referent of a
phantom reference is always inaccessible, this method always returns
| |
| refersTo0 | back to summary |
|---|---|
| private native boolean refersTo0(Object o) Hides java.
| |
| refersToImpl | back to summary |
|---|---|
| pack-priv boolean refersToImpl(T obj) Overrides java.
| |