Android Development with Kotlin

Returning functions

So far, most of the functions were defined like procedures (functions that do not return any values). But in fact, there are no procedures in Kotlin and all functions return some value. When it is not specified, the default return value is the Unit instance. We can set it explicitly for demonstration purposes:

    fun printSum(a: Int, b: Int): Unit { // 1 
        val sum = a + b 
        print(sum) 
    } 

1. Unlike in Java, we are defining the return type after the function name and parameters.

The Unit object is the equivalent of Java's void, but it can be treated as any other object. So we can store it in variable:

    val p = printSum(1, 2) 
    println(p is Unit) // Prints: true 

Of course, Kotlin coding conventions claim that when a function returns  ...