Re: A weird little problem about handling objects without knowing what they are

From:

Daniel Pitts <newsgroup.spamfilter@virtualinfinity.net>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 19 Jul 2008 16:02:52 -0700

Message-ID:

<488272bb$0$3220$7836cce5@newsrazor.net>

Tom Anderson wrote:

Hello!

I wonder if anyone has any ideas on how or whether i can do something.

[...snip...]

A slightly better option is to wrap the things inside a polymorphic
wrapper:

public interface Manageable {
}

public class FruitWrapper implements Manageable {
// ...
}

public class CloudWrapper implements Manageable {
// ...
}

This seems like the best idea. If you want to find the Pattern, I
believe its called the Adapter Pattern. It actually buys you at *least*
three things in this case.

1. Type safety. If you require a FruitWrapper, you can ask for it directly.

public void actOnFruit(FruitWrapper wrapper) {}

2. Polymorphism. (For your use case especially)

3. Encapsulation. Today FruitWrapper wraps an Element. Tomorrow it
could wrap something else altogether, or not even be a Wrapper at all.

There are other benefits to using this pattern, but I would say those
are the biggest ones.

Hope this helps,
Daniel.

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