Type of class which implements multiple interfaces

I'm currently trying to write some classes and I come accross the following problem:

I'm trying to write a class that implements some functionality from two interfaces

interface IA {
 public void doSomething();
}

interface IB {
 public void doSomethingToo();
}

And I have two classes implementing those interfaces:

class FooA implements IA, IB{

}

class FooB implements IA, IB{

}

Is there I way I can do this:

public <type> thisClassImGonnaUse = returnEitherFooAOrFooB();
thisClassImGonnaUse.doSomething();
thisClassImGonnaUse.doSomethingToo();