Casting

To cast from one type to another, Kotlin uses the as keyword. Here’s how you would cast Any type to an Int type:

fun casting(any: Any) {
    val num = any as Int
}

During runtime, before casting, the JVM will check if the source type can be cast to target type. If not, ClassCastException will be thrown.

Safe casting

There is also the safe casting operator, as?. This operator checks, before casting, whether or not types are compatible. If they are, then it works as a normal asoperator. If not, a null value is assigned. Notice how in this example, the local variable num has to be declared as a nullable type:

fun safeCasting(any: Any) {
    val num: Int? = any as? Int
}

Safe casts can be used with all other null...