Compiled and run in Kotlin.org website along with this article: https://proandroiddev.com/the-kotlin-guide-for-the-busy-java-developer-93dde84a77b7

Kotlin Playground

/**
 * You can edit, run, and share this code. 
 * play.kotlinlang.org 
 */

fun main() {   
    //Nullsafe operator
    var nickname: String? =null
    val uppercase = nickname?.toUpperCase()?:"Bor $nickname?"
    println(uppercase)
    
    //Type conversion explicit
    val i = 10
    val k : Long = i.toLong()
    println(k)
    
    //Array
    var intArr : Array<Int> = arrayOf(1,2,3)
    println(intArr[0])

   //Any type
  	var nice = 10L;
    var crazy : Any = nice
    println(crazy)
    
    //is Operator
    val isOp : String = "isOp"
    println(isOp !is String)
 	
    //Safe cast
    var safeCast:String = "safeCast"
    var safeCastLen :Int? = safeCast as? Int ?: 0
    println(safeCastLen)
    
    //For loop
    for(i in 0 until 10)
    	print("$i ")
    println()
    for(i in 10 downTo 0)
    	print("$i ")
    println()
    for(i in 10 downTo 0 step 2)
    	print("$i ")
    println()
    val array = arrayOf("Kotlin", "Java", "Gradle")
	for(s in array) 
    	print("$s ")
    println()
    for(index in array.indices)
  		print("array[$index] = ${array[index]}\t")
    println()
    for(c in "alphabet")
  		print("$c ")
    println()
    for(i in 0..10){
        if(i>5) break
        print("$i ")
    }
    println()
    for(c in 'a'..'z'){
        print("$c ")
    }
 }