Java – classes that implement interfaces without type parameters cannot be compiled

I have the following test codes:

public interface Container<I> {
    public void addClass(Class<?> clazz);
}

public class MyContainer implements Container {
    public void addClass(Class<?> clazz) {}
}

When trying to compile these two classes, I received the following error:

If I add a type to the container interface in mycontainer (for example < Object >), I will not receive an error

The problem is that I introduce type parameters into the container, which is part of the public API, so for compatibility, I can't make all implementation classes unable to compile

Does anyone have an idea? Is this a type erase problem? Is there a solution?

Solution

I think the problem is that if you use primitive types anywhere in the class declaration, you will choose to exit generics So this will work – note the parameter changes

public class MyContainer implements Container {
    public void addClass(Class clazz) {}
}

Starting from section 4.8 of the JLS:

I believe this is relevant... Container < T > The deletion of addclass (class clazz) is addclass (class clazz)

But basically, unless this is real legacy code, you should introduce type parameters into the interface as major changes