Is there a `findOr` fun like `find{}` in Kotlin collections but let me do another thing if the resul...

# android

[AmrJyniat]

Is there a findOr fun like find{} in Kotlin collections but let me do another thing if the result was null?

[Paul Woitaschek]

I don’t think there is as it wouldn’t provide much benefit over doing a ?:

[Paul Woitaschek]

I can’t see where that would be useful

users.findOrElse({ it.name == "Alice" }) {
  Person("alice")
}

[AmrJyniat]

val rightDevice = devices.find { it is AudioDevice.BluetoothHeadset 
} ?: 
devices.find { it is AudioDevice.WiredHeadset 
} ?:
devices.find { it is AudioDevice.Earpiece }

Trying to make this code a bit cleaner

[Paul Woitaschek]

That looks pretty clean to me already

[Paul Woitaschek]

fun <T : Any> List<T>.multiFind(vararg predicates: (T) -> Boolean): T? {
  predicates.forEach { predicate ->
    find(predicate)?.let { return it }
  }
  return null
}

😉

[Paul Woitaschek]

Ah or better: Go with a sorting!

devices.maxByOrNull {
  when(it) {
    is bluetooth -> 3
    is wired -> 2
    is earpiece -> 1
  }
}

[Zun]

What about “devices.any { it in listOfEnums }”

[Paul Woitaschek]

That original algorithm has a prioritization and prefers Bluetooth over wired over earpieces.

[hfhbd]

In theory, you could also iterate only once: return if bluetooth found or store the first wired and the first earpiece. and return wired ?: earpiece 🙂

var wired: Device? = null
var earpiece: Device?  = null
for (device in devices) {
  if (device is Bluetooth) { return device }
  if (device is Wired && wired == null) { wired = device }
  if (device is EarPiece && earpice == null) { earpiece = device }
}
return wired ?: earpiece

Even better with a sealed class and when