[jboss-dev] generic collection item type

[Adrian]

I've applied your patch, but I don't understand why the NPE happens?
Why wouldn't a class implement its interface?

Basically I want to write a test for what you were seeing.

ClassInfo info = ...;
info.getComponentType(); // Should not throw NPE! :-)

On Wed, 2007-08-01 at 11:03 +0200, Alexey Loubyansky wrote:
> Yes, it does work! Thanks!
> 
> I had to add a check that the interface implements the reference before 
> calling locateActualType because in case of Comparable<T> and so on I 
> would get NPE later. I checked out the trunk but it didn't build. So, 
> here is the diff.
> 
>         Type[] interfaces = clazz.getGenericInterfaces();
>         for (Type intf : interfaces)
> -      {
> -         Type result;
> +      {
> +         Class interfaceClass;
>            if (intf instanceof Class)
>            {
> -            Class interfaceClass = (Class) intf;
> -            result = locateActualType(reference, parameter, 
> interfaceClass, intf);
> -            if (result instanceof TypeVariable)
> -               result = getParameter(clazz, type, (TypeVariable) result);
> +            interfaceClass = (Class) intf;
>            }
>            else if (intf instanceof ParameterizedType)
>            {
>               ParameterizedType interfaceType = (ParameterizedType) intf;
> -            Class interfaceClass = (Class) interfaceType.getRawType();
> +            interfaceClass = (Class) interfaceType.getRawType();
> +         }
> +         else
> +            throw new IllegalStateException("Unexpected type " + 
> intf.getClass());
> +
> +         Type result = null;
> +         if (reference.isAssignableFrom(interfaceClass))
> +         {
>               result = locateActualType(reference, parameter, 
> interfaceClass, intf);
>               if (result instanceof TypeVariable)
>                  result = getParameter(clazz, type, (TypeVariable) result);
>            }
> -         else
> -            throw new IllegalStateException("Unexpected type " + 
> intf.getClass());
> +
>            if (result != null)
>               return result;

-- 
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Adrian Brock
Chief Scientist
JBoss, a division of Red Hat
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