Lambda implementation of interface in kotlin

Question

What would be the equivalent of that code in kotlin, nothing seems to work of what I try:

public interface AnInterface {
    void doSmth(MyClass inst, int num);
}

init:

AnInterface impl = (inst, num) -> {
    //...
}

Solution 1

If AnInterface is Java, you can work with SAM conversion:

val impl = AnInterface { inst, num -> 
     //...
}

Otherwise, if the interface is Kotlin...

interface AnInterface {
     fun doSmth(inst: MyClass, num: Int)
}

...you can use the object syntax for implementing it anonymously:

val impl = object : AnInterface {
    override fun doSmth(inst:, num: Int) {
        //...
    }
}

Solution 2

If you're rewriting both the interface and its implementations to Kotlin, then you should just delete the interface and use a functional type:

val impl: (MyClass, Int) -> Unit = { inst, num -> ... }

Solution 3

You can use an object expression

So it would look something like this:

val impl = object : AnInterface {
    override fun(doSmth: Any, num: Int) {
        TODO()
    }
}