the comparison operators (>, < etc) can call...

# getting-started

[Florian]

the comparison operators (>, < etc) can call directly to Java's own compareTo methods? They don't need Kotlin's Comparable interface?

[karelpeeters]

Java's compareTo is also from the Comparable interface.

[karelpeeters]

But for Kotlin code the Comparable interface isn't actually required, operator fun compareTo is enough.

[Florian]

but it also works with Java's Date and its compareTo is not an operator fun

[karelpeeters]

Yes, you need to implement Comparable or have operator fun compareTo.

[karelpeeters]

Or you know just consider it compiler magic, it maps java.util.Comparable to koltin.Comparable which has an operator.

[Florian]

Is the last sentence actually true?

[Florian]

or is there an extension function somewhere

[karelpeeters]

No it's true, there's a bunch of type mapping going on. If you have a list of kotlin.Comparable you can put a Date in it.

[Florian]

I see, thank you

[diesieben07]

java.util.Date is Comparable...

[karelpeeters]

Yes, so it matches the first one:

Yes, you need to implement Comparable or have operator fun compareTo.

[diesieben07]

I think I misread something up there. It's too early. ☕

[Florian]

but it's Java's Comparable?

[Florian]

Not Kotlin?

[diesieben07]

https://kotlinlang.org/docs/reference/java-interop.html#mapped-types

[Florian]

thanks