i have this basic class:
public class GameObjectFactory {
private List<CompositeGameObject> compositeGameObjs;
private GameObjects[] persistentObjs;
public GameObjectFactory(int gameID) {
compositeGameObjs = new ArrayList<CompositeGameObj
try {
persistentObjs = GameObjectsFactory.listGam
} catch (PersistentException pe) {
System.out.println(pe.getM
}
for (GameObjects gobj : persistentObjs) {
CompositeGameObject cobj = new CompositeGameObject(gobj.g
cobj.loadAssets();
compositeGameObjs.add(cobj
}
}
...
}
What i am trying to do is make the CompositeGameObject cobj = new CompositeGameObject(...); be generic, as there will be several subclasses that extend CompositeGameObject each with a slightly different implementation of the class. But this constructor method needs to be able to "see" these sub classes so that overridden methods will be used instead of the super method. i tried to do this :
public class GameObjectFactory<C extends CompositeGameObject> {
...
C cobj = new C(gobj.getObjectID());
cobj.loadAssets();
...
}
obviously it is important that 'C' always be a subclass of CompositeGameObject, so when i try this i get an "type C cannot be instantiated directly" error. what is the correct syntax (if any) to get this to work (if its possible). if its not possible, is there a different (possibly better?) way to achieve the same result? thanks.
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Is that a mandatory stuff that you should make use of Generics ? I don't think so !!! :-)
This is a kind of design problem. Try to make use of design pattern.
If your problem, "Factory Design Pattern" will do the thing.
Factory design pattern will create Sub classes of type you need.
For more info on it, have a look at here.
http://en.wikipedia.org/wi
http://www.dofactory.com/P
http://www.dofactory.com/P
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by: JathrekPosted on 2007-04-26 at 15:45:28ID: 18985728
The thing is, you're trying to use generics at runtime, which is not possible, as generics are being handled at compile time (it's just some kind of type checking that allows developers to directly use the good typing instead of having to cast Object into some other classes - it helps by allowing him to detect casting errors at development time, not after compilation - and once the checks are finished, the generics informations is "forgotten" in the compiled code).
So it's actually not possible to do something like "new K(...)", where K would be a generic keyword.
In fact, I advise you to try to do it some other way...
Maybe it would be possible to do it by simply not using generics and giving a CompositeGameObject factory as a parameter of the constructor of GameObjectFactory? Or maybe you could just give a Class object and instantiate the subclasses of CompositeGameObject using reflection (calling newInstance() on the Class object).
It's not really the answer you expected, but if you want more informations, just ask.