Re: Make this 'generic'

Lew <>
Sun, 25 Mar 2007 16:35:03 -0400
Sandy wrote:

I am storing objects of type Feat in the sample code. I have to also
store objects of type Modifier and in another place type Language.
Each time I used this generic vector manager class I would have a
different type of object in the vector, but each object in that vector
would always be the same type as all of the other objects in the

I MIGHT be able to do this with type Object, but if I do, will my
checking to see if they are duplicates work? Currently I cast things
in and out. If I tried to access the equals method without casting the
Object to a 'known' type I assume it will break.

I wouldn't write a new class for this. I would use three different
collections, like this:

Set <Feat> feats = new HashSet <Feat> ();
Set <Modifier> modifiers = new HashSet <Modifier> ();
Set <Language> languages = new HashSet <Language> ();

A Set cannot, by its very nature, have duplicates, so no need to check for
that any more.

No casting needed - each Set uses its generic base type to know which
"equals()" and "hashCode()" to invoke.

So when you want to add a particular Language object to the Set:

languages.add( new Language( "French", "fr", new Locale( "fr" ) ) );

If you want to do something to every Feat in feats you can do this:

   for( Feat feat : feats )
     moveThose( feat );

If you want to look up something by its name, you can use a

Map <String, Feat> featMap;
Map <String, Modifier> modifierMap;
Map <String, Language> languageMap;

Then you could use expressions like

Language french = languageMap.get( "fr" );

-- Lew

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