| A factory is responsible for creating new instances of "something".
Factories are commonly used in the implementation of
Adapteradapters .
Note that while the interfaces for adapters and factories are nearly the
same, the two don't do quite the same thing. Whereas an adapter is intended
to be associated with a
Container through the use of a
org.jicarilla.lang.Selector and is not required to always
return a new instance from its
Adapter.getInstance method, the
factory must always return a new instance on every call to its
Factory.newInstance() method, and is never directly associated with a
container.
If you do wish to add a factory implementation to a container, you should
use one of
org.jicarilla.containers.adapters several available to
wrap the factory.
Note that it is usually quite possible to use a factory without using an
adapter or a container. When you do, observe these contracts:
- method call ordering. You may not call
releaseInstance() until you have called
newInstance() at least once.
- method call pairing. You should call
releaseInstance() once for every time you call
newInstance(), and the parameter to
releaseInstance() must be the object you received
from newInstance().
(note that it is legal to call newInstance()
multiple times in a row and then call releaseInstance()
multiple times in a row.)
Also note that some Factory implementations may be less
strict about these rules. See the documentation for those implementations
to be sure.
author:
Leo Simons
version:
$Id: Factory.java,v 1.4 2004/03/23 13:37:51 lsimons Exp $ |