function MutableList<T>.moveDownAll() & moveUpAll() throw java.util.ConcurrentModificationException

[shinobi9]

I notice there is a modify operation in for-Each. Is that a mistake?

[SchweinchenFuntik]

version:
kotlin
tornadofx
javaFX
JVM

[shinobi9]

version:
kotlin: 1.5.21
tornadofx: 1.7.20
javaFX:
javafx.runtime.version=8.0.261
javafx.runtime.build=b12
JVM: 1.8 25.261-b12

[SchweinchenFuntik]

snippet of the code in which the problem is reproduced

PS: I understand what the error is, but I want to make sure that it is not related to your code, but the problem is in tornadofx

[shinobi9]

mutableListOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10).apply { moveDownAll{ true } }.also { println(it) }

Is it my use wrong ?
The original code is missing. but just like this.

[SchweinchenFuntik]

the problem is tornadofx. Although it is not clear why it began to reproduce right now. Try polle low version of Kotlin 1.4 or 1.3. Here is the code that fixes the problem.

inline fun <T> MutableList<T>.moveDownAll(crossinline predicate: (T) -> Boolean) = withIndex()
    .filter { predicate(it.value) }
    .forEach { moveDownAt(it.index) }

[shinobi9]

ok,thank you.
i will try later

[shinobi9]

It works well.

[SchweinchenFuntik]

I think it is not worth closing, since the problem in the library has not been fixed