Java Interface Observable
===

This is a little hard to explain but here goes. I have the following 

1) A Java class: ClassA implementes Observer

2) A Java Interface: Inter (extends Observale, not possible)

3) A Java class: ClassB implements Inter extends Observable

4) A Java class: ClassC implements Inter extends Observable

Now the code for ClassA is somewhat like this. 

    ClassA{
        Inter anyClass = new ClassB();
               //or it could be
        Inter anyClass = new ClassC();
        //Inter.addObserver(this); //not possible since Interface cannot extend Observable
    }

Now if a particular event happens in ClassB or ClassC, I want ClassA to know about it. I thought of using the Observer/Observable but the problem is that the Interface cannot extend Observable. 

If someone understands the question please help me find a way to update ClassA when something happens in ClassB or ClassC. 