Way to specify multiple interfaces in Java

Question

I have two interfaces, HasClickHandlers and DoesFancyFeedback. Then I have some UI objects that implement both interfaces - for example, a Button that implements both has click handlers and also does fancy feedback.

In my code that's declaring Buttons, I don't want to actually say Button because maybe later I'll want it to be, I don't know. An Image that has click handlers and does fancy feedback. So instead of being specific and saying something like:

Button saveButton = aButtonIPassedIn;
saveButton.addClickHandler();
saveButton.doFancyFeedback();

I want to say,

{HasClickHandlers + DoesFancyFeedback} clickyFeedbackThing = aThingIPassedIn;
clickyFeedbackThing.addClickHandler();
clickyFeedbackThing.doFancyFeedback();

I want the compiler to require that aThingIPassedIn implement both HasClickHandlers and DoesFancyFeedback.

I could create an interface that extends those two interfaces, and use that. Is there any easier/less verbose way?

Answer 1

No need for a third interface nor additional method.

Optional.ofNullable((HasClickHandlers & DoesFancyFeedback)clickyFeedbackThing).ifPresent(then -> {
    then.addClickHandler();
    then.doFancyFeedback();
});

Answer 2

I do not think that there is a better way to do what you want. I just wanted to suggest you to do the following. You can create method (let's call it foo) that accepts argument that requires 2 interfaces:

<T extends HasClickHandlers & DoesFancyFeedback> void foo(T arg);

Please pay attention on one ampersand between 2 your interfaces.