Kotlin : Declaring variables val vs var

In this article, we will see how to declare variables in Kotlin with examples.

We can declare variables in Kotlin using val or var keywords.

Variables declared using val keyword are essentially constants.

fun main(args: Array<String>) {
    val num = 10
    println("num = $num") //prints num = 10
    num = 20 // error.. val cannot be reassigned
}

We can create mutable variables using var keyword.

fun main(args: Array<String>) {
    var num = 10
    println("num = $num") //prints num = 10
    num = 20
    println("num = $num") //prints num = 20
}

We can also explicitly specify the type as shown below, but its not required.

fun main(args: Array<String>) {
    var num:Int = 10
    println("num = $num") //prints num = 10
    num = 20
    println("num = $num") //prints num = 20
}

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