How to do it...

First, let's create a file, name it whenWithRanges.kt, and follow these steps:

1. Let's try a basic when statement to understand how it works:

fun main(args: Array<String>) {
     val x = 12
     when(x){
         12 -> println("x is equal to 12")
         4 -> println("x is equal to 4")
         else -> println ("no conditions match!")
     }
 }

So basically, this code block works like a switch case statement, and it can also be implemented using an if statement.

1. Now, let's see if x lies between 1 to 10 or outside it:

fun main(args: Array<String>) {
     val x = 12
     when(x){
         in (1..10) -> println("x lies between 1 to 10")
         !in (1..10) -> println("x does not lie between 1 to 10")
     }
 }

1. Let's see what else we can do. In the following example, we will work with different types of conditions that can be used inside a when statement:

fun main(args: Array<String>) {
     val x = 10
     when(x){
         magicNum(x) -> println("x is a magic number")
         in (1..10) -> {
             println("lies between 1 to 10, value: ${if(x < 20) x else 0}")
         }
         20,21 -> println("$x is special and has direct exit access")
         else -> println("$x needs to be executed")
     }
}
fun magicNum(a: Int): Int {
 return if(a in (15..25)) a else 0
 }

1. Finally, let's try a more complicated example of using data classes. In this example, we will see how to use when with objects:

fun main(args: Array<String>) {
     val x = ob(2, true, 500)
     when(x.value){
         magicNum(x.value) -> println("$x is a magic number and         ${if(x.valid) "valid" else "invalid"}")
         in (1..10) -> {
             println("lies between 1 to 10, value: ${if(x.value <           x.max) x.value else x.max}")
         }
         20,21 -> println("$x is special and has direct exit access")
         else -> println("$x needs to be executed")
     }
 }
 data class ob(val value: Int, val valid: Boolean, val max: Int)
 fun magicNum(a: Int): Int {
 return if(a in (15..25)) a else 0
 }

Here's how it looks after compiling and running the program:

Try playing around with the values and logic to see what else you can do with such a small block of code in Kotlin using when.