I should have stated it clearly ..
i actually meant passing type Class in constructor itself like in following
code:-
class Funny<T> {
private Class<T>typeClass;
public Funny(Class<T>typeClass){
this.typeClass=typeClass;
}
}
class Funnier<T,R> extends Funny<T>{
private Class<T>typeClassT;
private Class<R>typeClassR;
public Funnier( Class<T>typeClassT,Class<R>typeClassR){
super(typeClassT);
this.typeClassT=typeClassT;
this.typeClassR=typeClassR;
}
}
--
regards,
Vineet Semwal
On Thu, Sep 17, 2009 at 2:58 PM, jWeekend <jweekend_for...@cabouge.com>wrote:
>
> Vineet ,
>
> Yes, this is a technique that, carefully and properly used, could help in
> building a generic DAO.
> Can you elaborate on "intializing the class type in constructor." ?
>
> Regards - Cemal
> jWeekend
> OO & Java Technologies, Wicket Training and Development
> http://jWeekend.com
>
>
>
>
> vineet semwal wrote:
> >
> > the first time I used genericsuperclass() was in generic daos after
> > reading https://www.hibernate.org/328.html,
> > though it has it's own quirks, it doesn't apply every where ..
> > abstract modifier in above code was needed,it's done so that one will
> > eventually subclass funnyfactory
> > and that genericsuperclass hack will work ..
> >
> > apart from that one another simple way for retrieving the generic
> > classtype
> > is intializing the class type in
> > constructor.
> >
> > conditions apply ;)
> > --
> > regards,
> > Vineet Semwal
> >
> >
> > On Thu, Sep 17, 2009 at 4:13 AM, jWeekend
> > <jweekend_for...@cabouge.com>wrote:
> >
> >> Since you can NOT do
> >>
> >> class S<T>{S(){T t = new T();}} // broken
> >>
> >> how would you create an object of type T somewhere in S? Think about
> this
> >> before you read on ...
> >>
> >> At the risk of reigniting the world-famous generics debates of
> >> yesteryear,
> >> just as our noble core-developers regroup to start work on making 1.5
> >> even
> >> better than what is already the best Java web framework, I thought I'd
> >> share
> >> the idea I suggested to one of our developers who was having a bad day
> >> with
> >> generics (for several good reasons [1][2]) a couple of months ago, in
> >> case
> >> you can make use of it somewhere, or, find an even more convoluted
> >> solution
> >> - notice the innocent looking abstract modifier!
> >> // not real code
> >> // don't try this at home without adult supervision!
> >> public abstract class FunnyFactory<T> {
> >> private T instance = null;
> >> public T getInstance() {
> >> if (instance == null) {
> >> try {
> >> final ParameterizedType gsc =
> >> (ParameterizedType)getClass().getGenericSuperclass();
> >> final Class<T> typeT = (Class<T>)
> >> gsc.getActualTypeArguments()[0];
> >> instance = typeT.newInstance();
> >> } catch (InstantiationException e) {
> >> e.printStackTrace();
> >> } catch (IllegalAccessException e) {
> >> e.printStackTrace();
> >> }
> >> }
> >> return instance; }
> >> }
> >>
> >> ...
> >>
> >> public class CreateInstanceOfTypeParameter {
> >> @Test
> >> public void testCreateInstanceOfTypeParameter() {
> >> FunnyFactory<Point> factory = new FunnyFactory<Point>() {};
> >> factory .getInstance().x = 22;
> >> factory .getInstance().y = 47;
> >> assertEquals(new Point(22, 47), factory.getInstance());
> >> }
> >> }
> >>
> >> Regards - Cemal jWeekend OO & Java Technologies, Wicket Training and
> >> Development http://jWeekend.com
> >>
> >> [1] http://gafter.blogspot.com/2006/11/reified-generics-for-java.html
> >> [2]
> >>
> http://weblogs.java.net/blog/arnold/archive/2005/06/generics_consid_1.html
> >>
> >>
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> >>
> >>
> >
> >
>
> --
> View this message in context:
> http://www.nabble.com/-OT--More-%22Java%27s-generic-type-parameters-are-not-reified%22...-tp25482235p25487989.html
> Sent from the Wicket - User mailing list archive at Nabble.com.
>
>
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