How to create an instance of anonymous interface in Kotlin?

Question

I have a third party Java library which an object with interface like this:

public interface Handler {
  void call(C context) throws Exception;
}
         


        

Answer 1

Assuming the interface has only a single method you can make use of SAM

val handler = Handler { println("Hello: $it") }

If you have a method that accepts a handler then you can even omit type arguments:

fun acceptHandler(handler:Handler){}

acceptHandler(Handler { println("Hello: $it") })

acceptHandler({ println("Hello: $it") })

acceptHandler { println("Hello: $it") }

If the interface has more than one method the syntax is a bit more verbose:

val handler = object: Handler2 {
    override fun call(context: String?) { println("Call: $context") }
    override fun run(context: String?) { println("Run: $context")  }
}