WeakReference with null referent
mandy chung
mandy.chung at oracle.com
Tue Jul 10 17:11:05 UTC 2018
On 7/9/18 11:59 PM, Peter Levart wrote:
>
> There are situations where being able to create a XxxReference without a
> referent is useful. For example, imagine a doubly-linked list of
> WeakReference subclasses - a special instance without a referent can be
> used as the head of such list that never goes away and simplifies
> insertion/deletion logic, etc...
>
> JDK's java.lang.ref.Cleaner API uses such scheme in its implementation
> (see jdk.internal.ref.CleanerImpl.[Phantom|Weak|Soft]CleanableRef no-arg
> constructors).
Thanks for pointing this out. It's used as a convenience and it's
not hard to handle insertion/deletion logic though. Another
alternative may be to create an object as the strongly reachable
referent. I wonder if any existing code depends on null referent
like the cleaner case and the compatibility risk. Do you know
any other example?
Mandy
More information about the core-libs-dev
mailing list