Kotlinで初め

/**
  * The `is` operator checks if an expression is an instance of a type and more.
  * If we is-checked an immutable local variable or property, there's no need
  * to cast it explicitly to the is-checked type.
  * See this pages for details:
  * http://kotlinlang.org/docs/reference/classes.html#classes-and-inheritance
  * http://kotlinlang.org/docs/reference/typecasts.html#smart-casts
 */
fun main(args: Array<String>) {
    println(getStringLength("asdfTest"))
    println(getStringLength(145623.toString()))
}


fun getStringLength(obj: Any): Int? {
    if (obj is String)
        return obj.length // no cast to String is needed
    return null
}