Kotlin asterisk operator before variable name or Spread Operator in Kotlin

Question

I want to know what exactly an asterisk does before a variable name in Kotlin. I saw this (*args) in a Spring boot Kotlin example:

@SpringBootApp         


        

Answer 1

If a function which accept a vararg(Variable number of arguments) parameter like:

fun sum(vararg data:Int)
{
   // function body here         
}

Now to call this method, we can do:

sum(1,2,3,4,5)

But what if we have these value in an array, like:

val array= intArrayOf(1,2,3,4,5)

then, to call this method we have to use spread operator, like:

 sum(*array)

Here, *(spread operator) will pass all content of that array.

*array is equivalent to 1,2,3,4,5

But wait a minute, what if we call it like this: sum(array) it will give us Type Mismatch compile time error:

Type mismatch.
Required:Int
Found:IntArray

The problem is sum function accept a vararg Int parameter(which accept value like: 1,2,3,4,5) and if we pass array, it will be passed as IntArray.