问题:

What is the equivalent of a static initialisation block in Kotlin?

I understand that Kotlin is designed to not have static things. I am looking for something with equivalent semantics - code is run once when the class is first loaded.

My specific use case is that I want to enable the DayNight feature from Android AppCompat library and the instructions say to put some code in static initialisation block of Application class.

回答1:

From some point of view, companion objects in Kotlin are equivalent to static parts of Java classes. Particularly, they are initialized before class' first usage, and this lets you use their init blocks as a replacement for Java static initializers:

class C {
    companion object {
        init {
            //here goes static initializer code
        }
    }
}

回答2:

companion object  { 
    // Example for a static variable
    internal var REQUEST_CODE: Int? = 500

    // Example for a static method
    fun callToCheck(value: String): String {
        // your code
    }
}

An object declaration inside a class can be marked with the companion keyword.And under this we can use like java static method and variable.LIke classname.methodname or classname.variablename