Can anyone explain this behavior to me? [Solved]

# announcements

[TheMrCodes]

Can anyone explain this behavior to me? [Solved]

[Rob Elliot]

Line 1 - false is not null, so false
Line 2 - false is still not null, so false != ScreenStates.Static is true

[Rob Elliot]

Unlike groovy, in kotlin the elvis operator is only for null defaulting, not for truthiness.

[TheMrCodes]

but in Line 2 why get "state != ScreenState.Static" called in the first place

[Rob Elliot]

It isn’t. false ?: state is evaluated. Then result of that is compared.

[TheMrCodes]

oh ok thanks now it makes sense

[TheMrCodes]

But i find it still very unintuitive
In my mind it would be like a logical operator where the right side only gets evaluated if the left is null

[Rob Elliot]

It is. It’s just the right side is just state. Left to right evaluation - imagine ?: and != are methods.

[TheMrCodes]

ow now i get it so "false.notNull(state) != ScreenStates.Static" equals true
It took a while 😅 but thanks for the explanation 🙏

[Klitos Kyriacou]

Hold on, isn't ScreenStates.Static an enum? Then why isn't it a compile-time error to compare it with a boolean?

[TheMrCodes]

I would guess because the return type of ?: is Any at compile time and then it's no problem to compare Any with an Enum