Invoke Methods dynamically using Method.invoke() with array that has the Parameters - kotlin

Question

I have below code which was supposed to call 2 methods concatenation(1, 2, mapOf("S" to "M")) and subtraction(5, 3):
private fun concatenation(a: Int, b: Int, c: Map<String, String>): String {
return a.plus(b).toString().plus(c.values.toString())
}
private fun subtraction(a: Int, b: Int): Int {
return a - b
}
#Test
fun test() {
val methods = listOf(
::concatenation,
::subtraction
)
val arguments = listOf(
arrayOf(1, 2, mapOf("S" to "M")),
arrayOf(5, 3)
)
val result = methods.zip(arguments).map { (method, args) ->
{
if (method.parameters.size == args.size) {
method.invoke(*args) //this line does not work
} else {
println("The number of arguments does not match the number of parameters in the target method")
}
}
}
println(result)
}
But I have error in method.invoke() because each method has different number of arguments.
How do I do this in Kotlin in an elegant manner?

Answer 1

The below code works if I change method.invoke() to method.call(). And remove private keyword for function or use the method.isAccessible = true.
fun concatenation(a: Int, b: Int, c: Map<String, String>): String {
return a.plus(b).toString().plus(c.values.joinToString())
}
fun subtraction(a: Int, b: Int): Int {
return a - b
}
#Test
fun test() {
val methods = listOf(
::concatenation,
::subtraction
)
val arguments = listOf(
arrayOf(1, 2, mapOf("S" to "M")),
arrayOf(5, 3)
)
val result = methods.zip(arguments).map { (method, args) ->
if (method.parameters.size == args.size ||
(method.parameters.size - 1 <= args.size && method.parameters.last().isVararg)
) {
//method.isAccessible = true
method.call(*args)
} else {
println("The number of arguments does not match the number of parameters in the target method")
}
}
println(result)
}