What types of delegates for interfaces do you know and apply in practice?

In Android development, the following types of delegates are often used for implementing interface delegation:

1. Anonymous classes — a classic way where the interface is implemented directly at the usage site. Convenient for one-time handlers.

2. Lambda expressions (starting from Java 8 and in Kotlin) — a more compact and readable way to implement interfaces with a single method (functional interfaces).

3. Classic delegates in Kotlin — using the by keyword to delegate the implementation of an interface to another object, simplifying code and increasing reusability.

Example of interface delegation in Kotlin:

interface ClickListener {
    fun onClick()
}

class ButtonClickHandler : ClickListener {
    override fun onClick() {
        println("Button clicked")
    }
}

class MyActivity(clickListener: ClickListener) : ClickListener by clickListener {
    // MyActivity delegates the implementation of ClickListener to the clickListener object
}

fun main() {
    val handler = ButtonClickHandler()
    val activity = MyActivity(handler)
    activity.onClick() // Will print: Button clicked
}

This approach helps to separate responsibilities and simplifies code maintenance.