Name: nt126004 Date: 02/01/2002


FULL PRODUCT VERSION :
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1-b24)
Java HotSpot(TM) Client VM (build 1.3.1-b24, mixed mode)


A DESCRIPTION OF THE PROBLEM :
  Today I was developing a CacheableDocument class, and I
wanted it to have some flexibility. Turning on/off the
cache was the main issue; the reference to the document's
content needs to be either strong (permanent) or weak
(disposable).

I thought "Oh, it's simple, let's just use a Reference
object, and assign a subclass of Reference to it". Wrong!
There is no StrongReference object... so I will have to
keep two fields for my document's content: one in case of a
WeakReference, and another in the case of non-disposable
String content.

Clearly, there is a need for a
java.lang.ref.StrongReference class. Maybe just for the
sake of completeness, or maybe because some concepts are
more easily expressed when declaring a
java.lang.ref.Reference field, and then assigning a
reference of any strength (strong, soft, weak, phantom) to
it.


STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
N/A (enhancement request)


This bug can be reproduced always.

CUSTOMER WORKAROUND :
Declare two fields:
- java.lang.ref.Reference
- java.lang.Object
and assign ONE of the two to your content, depending on
whether you need permanent or disposable content. This
requires some extra programming:

----

WeakReference cached;
Object noncached;

void setField(Object obj, boolean disposable)
{
  if(disposable) cached = new WeakReference(obj);
  else noncached = obj;
}

Object getField()
{
  return (cached == null) ? cached : noncached.get();
}

----

With a StrongReference class, it would be easier:

Reference ref;

void setField(Object obj, boolean disposable)
{
  if(disposable) ref = new WeakReference(obj);
  else ref = new StrongReference(obj);
}

Object getField()
{
  return ref.get();
}
(Review ID: 138567)
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