How I can use callback in Kotlin?

Question

I have View and one CircleShape , which should show toast in this View. And I use it in main Activity. This is my interface

interface OnClickListenerInterfa         


        

Answer 1

A more simpler solution by using lambda.

Inside CircleShape.kt, declare a lambda function.

var listener: (()->Unit)? = null
...
// When you want to invoke the listener
listener?.invoke()

Inside your Activity

mCircleShape.listener = {
    // Do something when you observed a call
}