How to instantiate class in Kotlin, if the class is parameter of function? - kotlin

Question

Im trying to make universal function in Kotlin, which can instantiate every time different model classes.
Class type is a parameter, to make instance from that class and fill it with data from Json object.
fun<T> foo() {
var myModel = T()
myModel.id = 2
myModel.name = ""
}

Answer 1

You can use an inline reified function in combination with an interface.
With reified you can access the real class of the generic type parameter.
You still not allowed to call the constructor directly, but reflection will work.
To assign the id and name, you need to define an interface, that all of your model classes are required to implement:
interface Model {
var id: Int?
var name: String?
}
inline fun <reified T : Model> createModel() : T {
val myModel = T::class.createInstance()
myModel.id = 2
myModel.name = ""
return myModel
}
A simple example:
class TestModel() : Model {
override var id: Int? = null
override var name: String? = null
}
fun main() {
val model: TestModel = createModel()
}

Answer 2

You cannot use T definition itself, pass class to the function instead.
import kotlin.reflect.KClass
open class Model {
var id: Int? = null
var name: String? = null
fun say() {
println("hello.")
}
}
class MyModel: Model()
fun<T: Model> foo(type: KClass<T>): T {
val myModel = type.java.newInstance()
myModel.id = 2
myModel.name = ""
return myModel
}
val mymodel = foo(MyModel::class)
mymodel.say() // hello.