Enthuware

new SimpleInterface() { ... }

if SimpleInterface is an interface, how can you instantiate it?

Exactly the way shown above It is actually instantiating an anonymous class that implements SimpleInterface.

It is only partial code. The part that is shown correctly instantiates the anonymous class.

new ComplexInterface(x) {    
//valid code
}

This is marked as a wrong answer
explanation is - You cannot pass parameters when you implement an interface by an anonymous class.

does that mean, you can pass parameters when implementing interfaces by a regular class?
Can interfaces have constructors?

boyonsea wrote:new ComplexInterface(x) {    
//valid code
}

This is marked as a wrong answer
explanation is - You cannot pass parameters when you implement an interface by an anonymous class.

does that mean, you can pass parameters when implementing interfaces by a regular class?

Yes, of course. A regular class can have any number of constructors with whatever parameters it needs. And it can implement an interface as well.

Can interfaces have constructors?

An interface can never be instantiated. So there is no question of it having a constructor.

new SimpleInterface() { ... }
Shouldn't this include a ';' after '}' to be completely valid?

It is not a complete code listing so doesn't really matter but yes, all options must be consistent in this respect.
thank you for your feedback!
Paul.