CODEWITHSUNDEEP
kotlinjava-timetype-mismatchdatetime-comparison
Vas
Vas

Reputation: 2064

Java8 time comparison in Kotlin

I stumbled across some strange behaviour when comparing Java8 time objects. The below does not appear to be valid code.

val t1 = LocalTime.now()
val t2 = LocalTime.now()
val foo: Int = t1 > t2

Yet hovering over the undersquiggled code shows that the overridden function return type is correct:

enter image description here

Any ideas?

Upvotes: 3

Views: 169

Answers (1)

SJoshi
SJoshi

Reputation: 1976

According to the documentation, when using the natively overloaded operators (comparison operators specifically) - Kotlin doesn't just call compareTo but rather performs a compareTo against 0 (thus ending up as a bool).

https://kotlinlang.org/docs/operator-overloading.html#comparison-operators

Comparison operators

Expression Translated to
a > b a.compareTo(b) > 0
a < b a.compareTo(b) < 0
a >= b a.compareTo(b) >= 0
a <= b a.compareTo(b) <= 0

All comparisons are translated into calls to compareTo, that is required to return Int.

The documentation snippet you attached is admittedly a bit confusing.

Upvotes: 2

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