Can primitive types be used in Kotlin?

Yes, it is possible. Kotlin compiles Java primitive types (int, boolean, float, etc.) into JVM bytecode, although they are represented as objects (e.g., Int, Boolean, Float) for the user, which offer additional methods and nullable versions. The Kotlin compiler optimizes the use of primitive types when it does not cause issues (for example, when working with non-nullable variables inside functions), avoiding unnecessary boxing/unboxing to improve performance.

For example:

fun sum(a: Int, b: Int): Int {
    // The compiler most likely uses primitive ints for addition
    return a + b
}

var nullableInt: Int? = null // Nullable type requires boxing