Re: [seam-dev] CDI with generic class and the hell of type erasure.

that´s an awesome solution Ales! I didn´t thought that I could obtain the parametizedType that way! Testing this will be my first task tomorrow morning. thank you all for your ideas. On Tue, Dec 6, 2011 at 8:55 PM, Jason Porter <lightguard.jp(a)gmail.com&gt;wrote: > Nice solution Ales, wish I'd thought of it :) > > > On Tue, Dec 6, 2011 at 15:45, Ales Justin <ales.justin(a)gmail.com&gt; wrote: > >> You could do something like this: >> >> @SuppressWarnings({"unchecked"}) >> @Produces >> public GenericQuery injectClass(InjectionPoint ip) { >> Annotated annotated = ip.getAnnotated(); >> Class clazz = Object.class; >> Type type = annotated.getBaseType(); >> if (type instanceof ParameterizedType) { >> ParameterizedType pt = (ParameterizedType) type; >> clazz = (Class) pt.getActualTypeArguments()[0]; >> } >> return new GenericQuery(clazz); >> } >> >> -- >> >> @Inject >> GenericQuery<String> gqs; >> @Inject >> GenericQuery<Number> gqn; >> >> -- >> >> System.out.println("GQS: " + gqs.getClazz()); >> System.out.println("GQN: " + gqn.getClazz()); >> >> -- >> >> GQS: class java.lang.String >> GQN: class java.lang.Number >> >> -- >> >> >> https://github.com/alesj/cdi-arq-workshop/commit/64860f15197be40a7714dfd8... >> >> HTH >> >> -Ales >> >> Hey guys, how you doing? >> >> I'm trying to achieve something that might be impossible, but before >> concluding that, I'd like to ask you, CDI gurus! >> >> I have the following class: >> >> public class Foo<T> { >> >> public TypedQuery<T> getQuery(){ >> >> } >> >> } >> >> As you can Imagine, inside my getQuery method, I'd have to use "T.class" >> to make it TypedQuery. which is impossible due java generics type erasure. >> >> so I'd have to build a private field to hold the t.class for me. >> >> public class Foo<T> { >> >> private Class<T> klass; >> >> public TypedQuery<T> getQuery(){ >> >> } >> >> public void setKlass(Class<T> klass){ >> this.klass = klass; >> } >> } >> >> The problem is that forcing this 'setKlass' feels very ugly to the api, >> and it's not very error prone, since one could easily forget to set this >> configuration. >> >> So I had an Idea: force the setKlass inside the constructor: >> >> public class Foo<T> { >> >> private Class<T> klass; >> >> public Foo(Class<T> klass){ >> this.klass = klass; >> } >> >> public TypedQuery<T> getQuery(){ >> >> } >> >> } >> >> Unfortunatelly, this breaks cdi, since it cannot inject it anymore. At >> least AFAIK. >> >> So, is there a way out of this? maybe using a secret solder feature? >> _______________________________________________ >> seam-dev mailing list >> seam-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/seam-dev >> >> >> >> _______________________________________________ >> seam-dev mailing list >> seam-dev(a)lists.jboss.org >> https://lists.jboss.org/mailman/listinfo/seam-dev >> >> > > > -- > Jason Porter > http://lightguard-jp.blogspot.com > http://twitter.com/lightguardjp > > Software Engineer > Open Source Advocate > Author of Seam Catch - Next Generation Java Exception Handling > > PGP key id: 926CCFF5 > PGP key available at: keyserver.net, pgp.mit.edu >