In Kotlin 1.0 you can do this by using Nothing from the stdlib. In Kotlin 1.1+ you will get “Forbidden vararg parameter type: Nothing” but you can replicate this pattern by defining your own empty class with a private constructor (like Nothing), and using that as the first varargs parameter. /* requires passing all arguments … Read more
With the new Dart extension functions, we can define: extension ObjectExt<T> on T { R let<R>(R Function(T that) op) => op(this); } This will allow to write x.let(f) instead of f(x).
You only need to specify semicolons in cases where it is ambiguous to the compiler what you are trying to do, and the absence of a semicolon would result in an obvious compiler error. The rule is: Don’t worry about this and don’t use semicolons at all (other than the two cases below). The compiler … Read more
Actually, a slight change to pwolaq’s answer guarantees that the second item is non-nullable: val map = listOf(Pair(“a”, 1), Pair(“b”, null), Pair(“c”, 3), Pair(“d”, null)) .mapNotNull { p -> p.second?.let { Pair(p.first, it) } } .toMap() println(map) This will give you a Map<String, Int>, since mapNotNull ignores anything that maps to null, and using let … Read more
You can use run with a return at label: when(transaction.state) { Transaction.Type.EXPIRED, //about 10 more types Transaction.Type.BLOCKED -> run { if (transaction.type == Transaction.Type.BLOCKED && transaction.closeAnyway) { close(transaction) return@run //close if type is blocked and has ‘closeAnyway’ flag } //common logic } //other types }
after reading some documentation I found that the error in my case was mainly due to two misconfigurations that I had: first: I needed to add the plugin in the gradle at the app and project level, I solved this as follows: adding in gradle.project the next line: id ‘org.jetbrains.kotlin.plugin.serialization’ version ‘1.6.21’ As is seen … Read more
val one = async { one() } val two = async { two() } val int1 = one.await() val int2 = two.await() What this does: spawn task one spawn task two await on task one await on task two val one = async { one() }.await() val two = async { two() }.await() What this … Read more
You can handle it like this: fun String.decodeHex(): ByteArray { check(length % 2 == 0) { “Must have an even length” } return chunked(2) .map { it.toInt(16).toByte() } .toByteArray() } Split the string into 2-character pairs, representing each byte. Parse each hex pair to their integer values. Convert the parsed Ints to Bytes.
With Kotlin 1.3, according to your needs, you may choose one of the following ways to solve your problem. #1. Using chunked fun main() { val list = listOf(2, 4, 3, 10, 8, 7, 9) val newList = list.chunked(2) //val newList = list.chunked(size = 2) // also works print(newList) } /* prints: [[2, 4], [3, … Read more
Since objects do not have constructors what I have done the following to inject the values on an initial setup. You can call the function whatever you want and it can be called at any time to modify the value (or reconstruct the singleton based on your needs). object Singleton { private var myData: String … Read more