From Java to Kotlin

Demo.java

public class Demo {
  public static void main(String[] args){

  }
}

Demo.kt

class Demo {

    fun init() {
        print(sum(1,2))
        print(sum(1,2))

        val items = listOf("apple", "banana", "kiwifruit")
        for (item in items) {
            println(item)
        }

        //val items = listOf("apple", "banana", "kiwifruit")
        //for (index in items.indices) {
        //    println("item at $index is ${items[index]}")
        //}
    }


    /**
     * Suma 2 enteros
     */
    fun sum(a: Int, b: Int): Int {
        return a + b
    }

    /**
     * Suma 2 flotantes
     */
    fun sum(a: Float, b: Float) = a + b

    /**
     * Usando expresiones condicionales
     *
     * fun maxOf(a: Int, b: Int) = if (a > b) a else b
     *
     */
    fun maxOf(a: Int, b: Int): Int {
        if (a > b) {
            return a
        } else {
            return b
        }
    }

    fun usingAForLoop() {
        val items = listOf("apple", "banana", "kiwifruit")
        for (item in items) {
            println(item)
        }
        // or
        for (index in items.indices) {
            println("item at $index is ${items[index]}")
        }
    }

    fun usingAWhileLoop() {
        val items = listOf("apple", "banana", "kiwifruit")
        var index = 0
        while (index < items.size) {
            println("item at $index is ${items[index]}")
            index++
        }
    }

    /**
     * Using When Expression
     */
    fun describe(obj: Any): String =
        when (obj) {
            1          -> "One"
            "Hello"    -> "Greeting"
            is Long    -> "Long"
            !is String -> "Not a string"
            else       -> "Unknown"
        }

 
    fun usingRanges() {
        val x = 10
        val y = 9
        if (x in 1..y+1) {
            println("fits in range")
        }
    }

    fun main(args : Array<String>) {
        var demo = Demo()
        demo.init()
    }

}