does kotlin have its own version of `Cloneable` as i cant find it in the docs nor in the search thin...

# announcements

[Smallville7123]

does kotlin have its own version of Cloneable as i cant find it in the docs nor in the search thing at kotlinlang.org

[ribesg]

Not sure what Cloneable is but every data class has a copy method

[fred.deschenes]

you can just use the one from java.lang

[Smallville7123]

Clonable supposidly provides the .clone() method in alot of java classes

[Smallville7123]

i cant access java in kotlin-native

[Smallville7123]

and kotlin.Cloneable does not exist

[fred.deschenes]

well java.lang.Cloneable is an empty interface anyway so just create your own I guess

[karelpeeters]

You should try to avoid in Java too, it's a mess.

[Smallville7123]

ok

[Smallville7123]

btw, if i have

var x = 1
fun a() {
    var y = x
    y = 6
    println(x)
    println(y)
}
a()

shouldnt x be modified such that y and x have the same value?

[karelpeeters]

No, that's not how variables work in most programming languages.

[karelpeeters]

You can think of variables as boxes, and x = y means "take the value that's in y and put it in x too". The boxes themselves, x and y, stay independent.

[Smallville7123]

ok, so y would obtain the value of x and not the reference to x itself?

[karelpeeters]

Yes.

[Smallville7123]

ok

[Smallville7123]

so to implement clone() i would do this?

fun clone(): LinkedList<T> {
        val tmp = LinkedList<T>()
        tmp.head = head
        return tmp
    }

if so would

fun clone(): LinkedList<T> = LinkedList<T>().head = head

also work?

[karelpeeters]

Assignments aren't expressions in Kotlin, so the second won't work and wouldn't do what you wanted anyway.

[dreamreal]

he doesn't understand kotlin much, unfortunately - he's been spamming other networks for weeks with the same stuff

[karelpeeters]

The first one appears to make a shallow clone, ie. if you mutate the clone the original will change too.

[Smallville7123]

so i would need this?

val tmp = LinkedList<T>()
        forEach { tmp.append(it!!) }
        return tmp

[karelpeeters]

Not sure why you've got the !!, but yeah.

[Smallville7123]

ok

[Smallville7123]

can lists normally accept null values as valid elements?

[Smallville7123]

eg MutableList<String?>().add(null)

[karelpeeters]

They take a type parameter T, and users can make it nullable if they want, like in your example String?. The list code itself doesn't need to concern itself with nullability.

[Smallville7123]

ok