How do I force a polymorphic call to the super method?

Question

I have an init method that is used and overridden through out an extensive heirarchy. Each init call however extends on the work that the previous did. So naturally, I would:

@Override public void init() {
   super.init();
}

And naturally this would ensure that everything is called and instantiated. What I'm wondering is: Can I create a way to ensure that the super method was called? If all of the init's are not call, there is a break down in the obejct, so I want to throw an exception or an error if somebody forgets to call super.

TYFT ~Aedon

Answer 1

Rather than trying to do that -- I don't think it's achievable btw! -- how about a different approach:

abstract class Base {
 public final void baseFunction() {
   ...
   overridenFunction(); //call the function in your base class
   ...
 }

 public abstract void overridenFunction();
}
...
class Child extends Base {
 public void overridenFunction() {...};
}

...
Base object = new Child();
object.baseFunction(); //this now calls your base class function and the overridenFunction in the child class!

Would that work for you?

Answer 2

Here's one way to raise an exception if a derived class fails to call up to the superclass:

public class Base {
    private boolean called;
    public Base() { // doesn't have to be the c'tor; works elsewhere as well
        called = false;
        init();
        if (!called) {
            // throw an exception
        }
    }
    protected void init() {
        called = true;
        // other stuff
    }
}