fun main(args: Array<String>) {
    val a = 3f
    val b = 3.14f
    println(a % 1 == 0f)
    println(b % 1 == 0f)
}

Would print the following:

true
false

So something like

if(foo % 1 != 0f)

You could also turn it into an extension functions/vals:

inline fun Float.isWhole() = this % 1 == 0f
inline fun Float.isNotWhole() = !isWhole()

or w/e you'd want to call them