How to define a non-ordinal enum in Kotlin?

I want to define an enum that values are not ordinal, for example:

enum class States(value: Int) {
    STATE_A(4),
    STATE_B(5),
    STATE_C(7),
    STATE_D(12)
}

How can I get the value of each item? For instance States.STATE_C should return 7.

You should define value as property (val) not as constructor parameter. After that it becomes accessible:

enum class States(val value: Int) {
    STATE_A(1),
    STATE_B(2),
    STATE_C(3),
    STATE_D(4)
}
...
println(States.STATE_C.value) // prints 3

Also consider to use ordinal, which may be suitable in your case:

enum class States {
    STATE_A,
    STATE_B,
    STATE_C,
    STATE_D
}
...
println(States.STATE_C.ordinal + 1) // prints 3

If you go with that approach, be careful - any change of States order can break your code.