decrementAndFetch

Atomically decrements the current value of this AtomicInt by one and returns the new value.

@ExperimentalAtomicApifun AtomicInt.decrementAndFetch(): Int(source)

import kotlin.concurrent.atomics.*
import kotlin.ExperimentalAtomicApi

@OptIn(ExperimentalAtomicApi::class)
fun main() {
    val counter = atomic(5)
    println("Initial value: ${counter.value}")   // 5
    val newValue = counter.decrementAndFetch()
    println("After decrementAndFetch: $newValue") // 4
}

Source