public class WeakHashtable extends java.util.Hashtable
Hashtableimplementation with weak keys. An entry in a
WeakHashtablewill automatically be removed when its key is no longer in ordinary use. More precisely, the presence of a mapping for a given key will not prevent the key from being discarded by the garbage collector and then reclaimed. When a key has been discarded its entry is effectively removed from the hashtable, so this class behaves somewhat differently from
Each key object in a
WeakHashtable is stored indirectly as
the referent of a weak reference. Therefore a key will automatically be
removed only after the weak references to it, both inside and outside of the
map, have been cleared by the garbage collector.
Implementation note: The value objects in a
WeakHashtable are held by ordinary strong references. Thus care
should be taken to ensure that value objects do not strongly refer to their
own keys, either directly or indirectly, since that will prevent the keys
from being discarded.
|Constructor and Description|
Constructs a new, empty weak hashtable with a default capacity and load factor.
Constructs a new, empty weak hashtable with the specified initial capacity.