Interface (two methods, different return types depending on class) Java

Question

Any class that extends an interface must implement the methods declared in the interface. Not sure if this is possible but what I want to do is the following :

Answer 1

You can do this with generics, but it's not enforced at runtime. You should also be using implements to implement an interface in a class, rather than extends.

interface Test {
   T get();
}

class A implements Test {
    int val;

    A(int x) {
        val = x;
    }

    @Override
    Integer get() {
       return Val;
    } 

}

class B implements Test {
    String val;

    B(String x) {
       val = x;
    }

    @Override
    String get() {
        return Val;
    }
}

Generics only apply to classes, so you're forced to use Integer rather than int as the return type.