Created
December 6, 2017 05:58
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firstIndexOrNull in Kotlin collections
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| inline fun <T> Iterable<T>.firstIndexOrNull(predicate: (T) -> Boolean): Int? { | |
| return this.mapIndexed { index, place -> Pair(index, place) } | |
| .firstOrNull() { predicate(it.second) } | |
| ?.first | |
| } |
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| val arr = arrayListOf("a", "b", "c") | |
| arr.firstIndexOrNull { it == "b"} // -> 1 | |
| arr.firstIndexOrNull { it == "z"} // -> null |
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