Class java.lang.Ref

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Class java.lang.Ref

java.lang.Object
   |
   +----java.lang.Ref

public class Ref
extends Object

A "Ref" is an indirect reference to an object that the garbage collector knows about. The application overrides 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 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.

Version:: 1.5, 16 Feb 1995

Ref(): Constructs a new Ref.

check()
flush(): Flushes the cached object.
get(): Returns a pointer to the object referenced by this Ref.
reconstitute(): Returns a pointer to the object referenced by this ref by reconstituting it from some external source.
setThing(Object)

Ref

  public Ref()

Constructs a new Ref.

get

  public Object get()

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. Does everything necessary to ensure that the garbage collector throws things away in LRU order. Applications should never need to override this method. get() effectively caches calls to reconstitute().

reconstitute

  public abstract Object reconstitute()

Returns a pointer to the object referenced by this ref by reconstituting it from some external source. It shouldn't bother with caching since 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().

flush

  public void flush()

Flushes the cached object. Forces the next invocation of get() to invoke reconstitute().

setThing

  public void setThing(Object thing)

check

  public Object check()

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