ArrayList of classes : ArrayList<Class> but how to force those classes to extend some super class?

Question

I want to manage an ArrayList of classes.

For instance, I have 3 types of filters : TextFilter, DurationFilter and TimeFilter which extend Filter.

That seems to be correct :

List<Class> filters = new ArrayList<Class>();

filters.add(TextFilter.class);
filters.add(DurationFilter.class);
filters.add(TimeFilter.class);

But now I want to restrain the ArrayList type with

List<Filter.class> filters = new ArrayList<Filter.class>();

filters.add(TextFilter.class);
filters.add(DurationFilter.class);
filters.add(TimeFilter.class);

But it seems that it is not correct. Can you explain why? Do you have a solution to only accept Filter child classes to be adde in my ArrayList? Thanks.

Answer 1

Use a ? in generics.

List<Class<? extends Filter>> filters = new ArrayList<Class<? extends Filter>>();

Since you want class objects and not the instances.

Answer 2

You should be able to say List<Class<? extends Filter>>

See Upper Bounded Wildcards