Class object of generic class (java)

Question

how about

(Class<List<Object>>)(Class<?>)List.class

public final class ClassUtil {
    @SuppressWarnings("unchecked")
    public static <T> Class<T> castClass(Class<?> aClass) {
        return (Class<T>)aClass;
    }
}

Now you call:

Class<List<Object>> clazz = ClassUtil.<List<Object>>castClass(List.class);

Because of type erasure, at the Class level, all List interfaces are the same. They are only different at compile time. So you can have Class<List> as a type, where List.class is of that type, but you can't get more specific than that because they aren't seperate classes, just type declarations that are erased by the compiler into explicit casts.

As mentioned in other answers, Class represents an erased type. To represent something like ArrayList<Object>, you want a Type. An easy way of getting that is:

new ArrayList<Object>() {}.getClass().getGenericSuperclass()

The generic type APIs introduced in 1.5 are relatively easy to find your way around.

You could use Jackson's ObjectMapper

ObjectMapper objectMapper = new ObjectMapper();
CollectionType listType = objectMapper.getTypeFactory().constructCollectionType(List.class, ElementClass.class)

No unchecked warnings, no empty List instances floating around.