Question

I am working on a project in which, to resolve a versioning issue, I am creating many classes which will never be tested and must not ever be used – they just need to be there to keep the compiler happy. I’d like to make sure they are never used. This morning I had the idea of throwing an exception in a static initialization block:

public class Dummy {

    static {
        throw new IllegalStateException("Do not use this class!");
    }
}

But the compiler doesn’t like it. Can you think of any way to do this?

EDIT: to be clear (my fault I wasn’t clear before), these won’t just be empty classes. There will be all sorts of code in here, and by “keep the compiler happy” I did indeed mean that elsewhere I will be instantiating them, calling methods etc etc. I want this code elsewhere to compile but fail at runtime. I have accepted Jon’s answer but will also be using @Deprecated and documenting extensively as appropriate.

Answer 1

Just add a dummy condition:

public class Dummy {    
    static {
        if (true) {
            throw new IllegalStateException("Do not use this class!");
        }
    }
}

I’m not really sure I like this, but it may do what you want it to. Are you sure there’s no alternatively which would let you get away without having a completely useless class like this?