I m updating a Java codebase to Kotlin I m stuck on trying t

Question

I m updating a Java codebase to Kotlin I m stuck on trying to update `Arrays copyOfRange ` ```fun copyData codePointsWindow IntArray pointer Int dataLength Int read Int IntArray return Arrays copyOfRange codePointsWindow pointer dataLength + read ``` IntelliJ pops up a warning Should be replaced with Kotlin function and provides a quickfix ```return codePointsWindow copyOfRange pointer dataLength + read ``` However then a lot of tests fail with ```toIndex 11 is greater than size 0 java lang IndexOutOfBoundsException toIndex 11 is greater than size 0 at kotlin collections ArraysKt ArraysJVMKt copyOfRangeToIndexCheck ArraysJVM kt 49 at kotlin collections ArraysKt ArraysJvmKt copyOfRange ArraysJvm kt 1859 ``` I ve made an issue <https youtrack jetbrains com issue IDEA 320926|IDEA 320926> for the quickfix not producing equivalent code but can someone help me with a suitable replacement for now

Adam S · Answer

I think the difference is that `Arrays copyOfRange ` allows for the index to lie outside of the source array s bounds while Kotlin s `copyOfRange ` performs a check

Adam S · Answer

alright this util function seems to work ``` Like IntArray copyOfRange but allows for toIndex to be out of bounds private fun IntArray copyOfRangeSafe fromIndex Int toIndex Int IntArray = IntArray toIndex fromIndex getOrNull fromIndex + it 0 ``` thank for rubber ducking rubber duck any further suggestions or refinements are welcome

hho · Answer

Or simpler ```fun IntArray copyOfRangeSafe fromIndex Int toIndex Int = copyOfRange fromIndex toIndex coerceAtMost size ```

Adam S · Answer

that one fails if `fromIndex == toIndex` ```java lang ArrayIndexOutOfBoundsException Index 0 out of bounds for length 0```

hho · Answer

disappointed You re right But I d still prefer to fix the param ranges and use the `copyOfRange` function instead of doing the copying yourself

Adam S · Answer

me too

hho · Answer

is your source array empty for me fromIndex == toIndex works

Adam S · Answer

yeah I think it might be

Adam S · Answer

yeah it is `println indices ` returns `0 1`

hho · Answer

But yeah what IntelliJ suggests definitely is not equivalent

hho · Answer

I d probably just use the Java method then

Adam S · Answer

the plan is to eventually convert to Kotlin Multiplatform so it would have to be replaced at some point

Klitos Kyriacou · Answer

`toIndex coerceAtMost size ` will not work because Java s `copyOfRange` guarantees the returned array will have size `toIndex fromIndex`