Re: Javax Swing Interfaces and Generics

From:
Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 04 Aug 2009 20:38:10 -0700
Message-ID:
<G87em.63421$O23.59435@newsfe11.iad>
markspace wrote:

Roedy Green wrote:

Rather than creating a generalised implementation, you might just wrap
a class with a particular class built in, WITHOUT generics.


Again, because of the way polymorphism works, it's impossible to
actually provide a wrapper for (for example) TreeModel that overrides
the methods needed instead of overloading them.

It does occur to me that there is a second pattern in the Adapter family
(which includes Wrapper) that might be useful. You could define your
own, totally separate interface:

// A very simple interface
interface FooModel {
  void setFooInTree( Foo f, index i );
  void Foo getFooFromTree( index i );
}

And then wrap that with a TreeModel, using the Class Adapter pattern.
Kind of the reverse of what's being suggested with the Wrapper pattern.

class FooTreeModel extends DefaultTreeModel implements FooModel {

  // implement FooModel here in terms of TreeModel...

}

This will still expose the TreeModel interface (which you must, to get
it to work with a JTree), but as long as your controllers, data models,
and such-like are coded to and tested against FooModel, you should
achieve reasonable separation and not be bothered by the extra methods
in FooTreeModel.

Just my 2 cents.


TreeModel really should not be used to store your app-data. Do you
really want to couple your Domain model with Swing classes? Instead,
you should create TreeModel implementation that queries your domain model.

--
Daniel Pitts' Tech Blog: <http://virtualinfinity.net/wordpress/>

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