KotlinEnumSample.kt

inline fun <reified T: Enum<T>> String.enumValueOfOrNull() : T? {
    return enumValues<T>().find { it.name == this }
}

enum class SampleEnum(val code:Int) {
  Ja(1), En(2)
}

fun main(args: Array<String>) {
  val sampleString = "Ja"
  val sampleEnum = sampleString?.enumValueOfOrNull<SampleEnum>()
  if (sampleEnum == null)  {
    print("sampleEnum is null")
  } 
  print(sampleEnum.code)         
}