| java.lang.Object
 sun.misc.Ref
All known Subclasses: sun.applet.AppletImageRef, sun.misc.CacheEntry, sun.awt.image.PixelStore,
| Ref | | abstract public class Ref (Code) | | A "Ref" is an indirect reference to an object that the garbage collector
knows about. An application should override the reconstitute() method with one
that will construct the object based on information in the Ref, often by
reading from a file. The get() method retains a cache of the result of the last call to
reconstitute() in the Ref. When space gets tight, the garbage collector
will clear old Ref cache entries when there are no other pointers to the
object. In normal usage, Ref will always be subclassed. The subclass will add the
instance variables necessary for the reconstitute() method to work. It will also add a
constructor to set them up, and write a version of reconstitute().
See Also: java.util.SoftReference
version:
1.35, 10/10/06 |
| Constructor Summary | |
| public | Ref()
Constructs a new Ref. | | public | Ref(Object thing)
Constructs a new Ref that initially points to thing. |
| Method Summary | |
| public synchronized Object | check()
Checks to see what object is being pointed at by this Ref and returns it. | | public synchronized void | flush()
Flushes the cached object. | | public synchronized Object | get()
Returns a pointer to the object referenced by this Ref. | | abstract public Object | reconstitute()
Returns a pointer to the object referenced by this Ref by
reconstituting it from some external source (such as a file). | | public synchronized void | setThing(Object thing)
Sets the thing to the specified object. |
| Ref | | public Ref()(Code) | | Constructs a new Ref.
|
| Ref | | public Ref(Object thing)(Code) | | Constructs a new Ref that initially points to thing.
|
| check | | public synchronized Object check()(Code) | | Checks to see what object is being pointed at by this Ref and returns it.
|
| flush | | public synchronized void flush()(Code) | | Flushes the cached object. Forces the next invocation of get() to
invoke reconstitute().
|
| get | | public synchronized Object get()(Code) | | Returns a pointer to the object referenced by this Ref. If the object
has been thrown away by the garbage collector, it will be
reconstituted. This method does everything necessary to ensure that the garbage
collector throws things away in Least Recently Used(LRU) order. Applications should
never override this method. The get() method effectively caches calls to
reconstitute().
|
| reconstitute | | abstract public Object reconstitute()(Code) | | Returns a pointer to the object referenced by this Ref by
reconstituting it from some external source (such as a file). This method should not
bother with caching since the method get() will deal with that.
In normal usage, Ref will always be subclassed. The subclass will add
the instance variables necessary for reconstitute() to work. It will
also add a constructor to set them up, and write a version of
reconstitute().
|
| setThing | | public synchronized void setThing(Object thing)(Code) | | Sets the thing to the specified object.
Parameters:
thing - the specified object |
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