We have extension functions. But i dont want to write a for loop

Let's say I have these 2 Java methods:

public String get(Integer key) {...}

public String get(int key) {...}

How can I call one of these without running into overload resolution ambiguity?

How I can return a function within itself? it’s like def f(x): print(x) return f then I can do f(1)(2)(3)

Hey folks, I'm having an issue trying to use an

internal

class from a test within the same module (test & class packages are different though). According to the docs, it should work: https://kotlinlang.org/docs/reference/visibility-modifiers.html#modules (see "Modules", 3rd option). I'm using Kotlin Multiplatform though, hence my source sets are called

commonMain

and

commonTest

, not just

main

and

test

. Could this be causing this access issue? Is this a bug?

Hi! How can I specify the classpath of kts Script Engine? upd: I want to load a kts file but encapsulate the implementation of my program

Hello, fellow Kotliners! Recently I’ve came across a following problem. I was implementing a custom Android view, and the base View I was extending had

setEnabled

method. I’ve overridden it in my class, and used properties from the child class in this overwrite. As the properties I’ve used were unmutable and non-nullable I was startled when my app crashed with

NullPointerException

thrown in that method. Turns out it was called from the superclass constructor, and properties are initialized only after superclass constructor call. The simplified code that caused my problem looks something like: https://bit.ly/2n6xmm5 . When you run it, it throws

NullPointerException

when using seemingluynon-nullable property. Is there a pattern that would allow us to omit method calls on unitialized unmutable properties? I found two solutions to that problem, but I don’t think they’re very elegant. One using lateinit vars https://bit.ly/2nPYBBX - pretty ugly, and one using a flag https://bit.ly/2mgG4hq - pretty weird. All of the urls are shortened https://play.kotlinlang.org code snippets.

Guys, I have two lists of same length. Want to iterate them in parallel. Is there a good kotlin way of doing it or just use a for loop with index approach?

hello everyone, i am looking for a control function

elseIf

it should allow me to take another value if the predicate does return true. i implemented the following extension function:

inline fun <T> T.elseIf(predicate: T.() -> Boolean, supplier: () -> T) : T =
        when {
            predicate() -> supplier.invoke()
            else -> this
        }

its called like

val i = "ssss".elseIf({isEmpty()}) {"other"}

which feels very clumsy. can i optimize the syntax more? or arent there already alternatives in kotlin? or maybe im just missing the easy solution?

I feel like a broken record but just use if!

Hi guys! Is there any way to use triple backticks in KDoc and still have links inside?

Hey guys, does anybody know how to use the fully qualified name to an extension function? eg

package asdf

fun Any.doThing() = TODO()

//...
package main

//no import statements

fun outer(){
  42.doThing() //<-- auto import `asdf.dothing`? 
  //No! I want to write the fully-qualified invocation instead!

  asdf.doThing(42) //error
  42.asdf.doThing() //error
  42.`asdf.doThing`() //error
}

coroutines on the jvm, is there some kind of underlying executor service that can be grabbed?

Folks, how do I choose which one to use between ArrayList and MutableList? and what are the ups and downs?

is there a way to redefine the same class or interface multiple times with only its amount of generic types differing

interface Event<out TS> { ... }
interface Event<out TS, out T0> { ... }
interface Event<out TS, out T0, out T1> { ... }

I have to override a Java method that uses an

@NonNull

annotation on a parameter even though documentation (and common sense) says that it can be null. If I make the same parameter nullable in my overriding Kotlin method, the compiler complains to me that I'm not overriding. But if I don't, then the function will crash at the hidden parameter assertion that is generated automatically. How do I tell the compiler "shut up, I know what to do"? Can I disable null-assertions for just this method?

Hey guys! While reviewing PR I've spotted a smelly code.

fun x(anInt: Int) : String {
    when (anInt) {
        0 -> return "zero"
        1 -> return "one"
    }
    return null!!
}

Despite the 'quality` of code itself I'm curious why compiler thinks that

return null!!

is fine (IDE hints that return statement is unreachable which is false)? And similarly why this

val a : Int = null!!

is allowed as well.

message has been deleted

Does anyone know if Kotlin native supports multithreading on IOS?

is there an idiomatic way to process an infinite sequence in parallel?

hi @all I need to know whether to use data binding in MVVM?

I'm not sure if this is a bug or not? but I have a large project, and when ever I'm doing some small change that makes my code uncompilable and I press run in IntelliJ. It shows me all the errors but it compiles anyway and the stuff actually works, I think it's using some old already compiled code. But is it supposed to do this?

I just ran into a seeming shortcoming in the type inference system, can't find any tickets on youtrack, has anyone else run in to this?

// both Foo and Bar extend Item
val item: Any? = getSomething()
if(item is Foo || item is Bar) {
  // I would expect this to smart cast to Item -- defining Item as a sealed class doesn't seem to help either
  doThingWithItem(item) //Error - Type mismatch, required: Item, found Any?
}

I wouldn’t have expected that

"<test>.*</test>".toRegex()
    .find("aaaa<test>5</test>aaaa<test>4</test>aaaa")
    ?.let { println("match: ${it.value}") }

doesn’t return the minimal first match <test>5</test>, but the longer one <test>5</test>aaaa<test>4</test> given that the documentation says: “Returns the first match of a regular expression” here: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/-regex/find.html And unfortunately findAll equally just returns a single match instead of two. Is there a way for me to fix this? Playground link: https://pl.kotl.in/HA-C02_Gy

This message was deleted.

How do I remove the prefix generated for objective c class names?(to className instead of frameworkNameClassName)

Hi, if we have a method on a abstract class, like this:

abstract fun test() : String

can we, using somehow the new kotlin techniques to change the returning value of the function in the other abstract class which extend the first one, something like this?

fun test(): String {
    return test().toString()
}

fun test(): Int {
}

The goal would be use to reuse the same name. Maybe something using the

by

keyword somehow? Composing the objects (where the problem here is that I have two abstract classes)

So I’m adding Kotlin to a previously Java-only project. I’m following these instructions https://kotlinlang.org/docs/reference/using-maven.html But now my

mvn clean package

commands frequently time out with a “Java heap space” error when using

maven-assembly-plugin

. Increasing my java/maven memory doesn’t fix it. I’ve added a single “hello world” type of Kotlin file, so I’m not sure why just adding the compiler for Kotlin pushes the entire build way over the edges. Has anyone else hit this before when adding Kotlin to a Java project?

I have a pretty big hierarchy of sealed classes where all the leafs are data classes. Basically every subclass is just the superclass plus some extra values. Sometimes the subclasses are even identical except for the name, which signifies a different kind of the object. How can I construct values of this class hierarchy without having lots of code duplication? Delegation is hardly possible, since the common superclasses are sealed and thus can't be extended to make delegate objects for them. Basically what I want to do is to have one function that makes `Car`s and then take that

Car

and promote it a

BMW

or

Toyota

by adding some values to it.

is it possible to ignore SSL certificate error when using the Ktor IOS httpClient?