Java Integer.MAX_VALUE vs Kotlin Int.MAX_VALUE

Question

I noticed, one interesting thing.
Java's Integer.MAX_VALUE is 0x7fffffff (2147483647)
Kotlin's Int.MAX_VALUE is 2147483647
but if you write
in Java:
int value = 0xFFFFFFFF; //everything is fine (but printed value is '-1')
in Kotlin:
val value: Int = 0xFFFFFFFF //You get exception The integer literal does not conform to the expected type Int

Interesting right? So you're able to do something like new java.awt.Color(0xFFFFFFFF, true) in Java but not in Kotlin.

Color class works with that int on "binary" level, so everything works fine for both platforms with all constructors (Color(int rgba) or Color(int r, int g, int b, int a)).
Only workaround which I found for kotlin is java.awt.Color(0xFFFFFFFF.toInt(), true).

Any idea why is it like this in Kotlin?

Answer 1

I think, this problem should be solved by Kotlin 1.3 and UInt See more here: https://kotlinlang.org/docs/reference/whatsnew13.html#unsigned-integers

Answer 2

This is partially answered here:

In Kotlin you need to prepend the - sign to denote negative Int which is not true in Java.

So it seems that Java will interpret hex literals as signed, whereas Kotlin will treat them as unsigned.

The negation would have to be done manually.

Small aside: JetBrains' Kotlin converter actually converts

int a = 0xffffffff;

to

var a = -0x1

but this may just be it realizing exactly what you have noticed.

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The part of the spec for hexadecimal literals doesn't mention this at all, however.