Hi, I run into an issue... I have this class:

data class Hotel(
  val id: String,
  val openStatus: OpenStatus //OpenStatus is an enum with values OPEN, PREORDER, CLOSED
  val favorite: Boolean
  val sortingValue: Int
)

Now I have a list of hotels. I want to sort the list in a way that it results in this:

Open/preorder section (openStatus == OPEN || openStatus == PREORDER)
  Favorites
    Open
      Sorted by sortingvalue
    Preorder
      Sorted by sortingvalue
  Non-favorites
    Open
      Sorted by sortingvalue
    Preorder
      Sorted by sortingvalue
Closed section (openStatus == CLOSED)
  Favorites
    Sorted by sortingvalue
  Non-favorites
    Sorted by sortingvalue

What would be the best way to achieve this sorting behavior?

I’m probably alone in this, but… I keep running into situations where I want to take an anonymous object (with properties on it, natch) and then add new fields to it, creating a /new/ anonymous object with all the same fields but one or two more things on it.

OK. After more testing, it turns out that trying to use

kotlinc

on code that references Scala 2.12.11's

List

(or any other class that references

TraversableOnce

) causes the compiler to crash. A minimal example is:

import scala.collection.JavaConverters.asScalaBuffer

fun main() {
    val kotlinList: List<String> = listOf("abc", "def", "ghi")
    val scalaList = asScalaBuffer(kotlinList).toList
    println(scalaList)
}

This works fine with Scala 2.12.10, but won’t even compile with Scala 2.12.11. The difference seems to be https://github.com/scala/scala/blob/v2.12.10/src/library/scala/collection/TraversableOnce.scala#L102 vs https://github.com/scala/scala/blob/v2.12.11/src/library/scala/collection/TraversableOnce.scala#L117 where they introduced a

reverser

object that is confusing Kotlinc’s bytecode analysis.

Is it possible to have lazy extension properties with access to

this

? This wont work:

val Delegado.number: Int by lazy {
    println("Executed")
    this.id + 1
}

I want to parse Kotlin code from Java (or actually Clojure, but Java is fine). I found this link explaining how to do it:

<https://jitinsharma.in/posts/parsing-kotlin-using-code-kotlin/>

Now I have converted that Kotlin code to Clojure, but when I try to access this field:

public final val importList: org.jetbrains.kotlin.psi.KtImportList?

Living in this class:

org.jetbrains.kotlin.psi.KtFile

In this library:

org.jetbrains.kotlin/kotlin-compiler-embeddable "1.3.72"

The problem is that this field is a val and that it's not annotated with @JvmField (that is my guess) and therefore I don't know how to access it. Can I use reflection or is there another way?

Basic Kotlin question here. If I wanted to move the decimalPrecision into the when (for example when(decimalPrecision)), is there a way I can still compare the value against <= 0 ?

Could someone explain and/or provide a link that lays it out in layman terms what Kotlin DSL is and how its relates to

build.gradle

? After reading https://www.raywenderlich.com/2780058-domain-specific-languages-in-kotlin-getting-started it's still not clicking.

Hi, can someone help me to enable xml reports for unit tests in a multiplatform project (gradle)? Currently, only a html report is generated. Many thanks.

Hey! I have a question: What's an idiomatic way of doing this: I have a List<Foo> fooList , and Foo has properties .isA(), isB() which returns a boolean. I receive a list of properties 'state' with elements A, B, and I have to filter the list for those properties. I'm thinking of something like this:

fooList.filter { if (state.contains('A') it.isA() else false || if (state.contains('B') it.isB() else false }

but it looks ugly

Should

internal

field be visible from the test code? It works when I run compile and test tasks from Gradle, but when I work with code in IntelliJ it is marked as an error.

How are teams using Kotlin and Cucumber? It would be useful to understand how you've setup your

build.gradle.kts

files. Bonus points if it is configured using an entirely separate

sourceSet

Hello guys, I basically want to do the following:

class Dto(val name: String, val age: Int, val somethingElse: String) {
    var signedKey = ""

    fun encrypt(shaSign: String): String {
        /*do something with all constructor fields*/
        return "encryptedString"
    }
}

the function

encrypt(shaSign: String)

returns an encrypted string by hashing the fields

name

,

age

and

somethingElse

. I basically just want to set the field

signedKey

with the output of that operation.

val dto = Dto("John", 36, "something else")
dto.signedKey = dto.encrypt("someShaKey")

Ofc I could do it like that, but that is really not a good way. I thought a bout a distinct setter which takes a parameter (some sign), executes

encrypt

and places the returned value as

signedKey

. How could I achieve that? Thanks ahead!

Is there a way to convert Kotlin to Readable Java?

message has been deleted

is that possible to make Int and String to inherit an interface?

Hello, World! Isn't there a shorter way to do this (with

by

)?

var parameter: Parameter
        set(value) {
            delegate.parameter = value
        }
        get() = delegate.parameter

Hi! I moved my domain logic classes to a new module, and getting this error:

Smart cast to 'UserInput.Some' is impossible, because 'alert.earliestSymptomTime' is a public API property declared in different module 

code:

when (alert.earliestSymptomTime) {
    is UserInput.Some -> alert.earliestSymptomTime.value.value
    is UserInput.None -> null
}

Why does it happen? Seems weird. And is there a way to fix it without having to cast? I didn't expect that modularizing my app would lead to a decline in code quality 😕

Does a function reference allocate a new object?

data class Item(val id: Int)
fun randomItem(block: (Int) -> Item) {}

// this
List(100) { randomItem(::Item) }

// vs
val constructor = ::Item
List(100) { randomItem(constructor) }

assertEquals(
            BigDecimal("0.08333333333333333"),
            (1.toBigDecimal() / 12.toBigDecimal())
        )

expected: <0.08333333333333333> but was: <0>

The bottom evaluates to

0

which is clearly incorrect. What is the rule here and how can I avoid this pitfall?

This message was deleted.

Why does

coerceAtLeast

has more priority then

-

?

-2.coerceAtLeast(0) == -2

I want to call Kotlin functions from Java, but when I disassamble the compiled Kotlin code, I can see that the types are e.g. kotlin.String instead of java.lang.String. Is there a way to compile the Kotlin code to Java types directly, or do we need to call the Kotlin code with e.g. kotlin.String, and if so, how do we convert from Java types to Kotlin types?

Why does line 6 still prints "A" here, see https://stackoverflow.com/questions/62595494/linkedlist-remove-element-puzzle

fun main(args: Array<String>) {
        var tree = Node("A", null, null)
        val q: Queue<Node> = LinkedList()
        q.add(tree)
        tree = q.remove() // line 5, remove element in q and assign to tree so tree so should size 0
        println(tree.data) // line 6, why does this still print "A" though?
}
// given
class Node {
    var data: String
    var left: Node? = null
    var right: Node? = null

    constructor(data: String) {
        this.data = data
    }

    constructor(data: String, left: Node?, right: Node?) {
        this.data = data
        this.left = left
        this.right = right
    }
}

is there some good reading material on how people stylistically handle the fact that you can have top-level functions without classes in Kotlin? Do you ever create stateless classes or is it more common to just declare stuff with functions and import the function?

if parsing/generating kotlin is your thing, there’s also my kibble project: https://github.com/evanchooly/kibble

Are inline classes okay to use for internal-only code in libraries, i.e. if they’re not exposed as part of the public API?

How does reading files with kotlin work? I want to read a json file and parse it, im on a javascript with gradle project

I just got a frontend compiler bug in Intellj (when trying to run my code). This used to work w/o problems until a few moments ago. "Invalidate cache and restart" did not help. IntellJ uses 720 of 1950MB right now.

Error:Kotlin: [Internal Error] java.rmi.ServerError: Error occurred in server thread; nested exception is: 
	java.lang.OutOfMemoryError: Java heap space
	at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:386)
	at sun.rmi.transport.Transport$1.run(Transport.java:200)
	at sun.rmi.transport.Transport$1.run(Transport.java:197)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.rmi.transport.Transport.serviceCall(Transport.java:196)
	at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:573)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:834)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.lambda$run$0(TCPTransport.java:688)
	at java.security.AccessController.doPrivileged(Native Method)
	at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:687)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
	at sun.rmi.transport.StreamRemoteCall.exceptionReceivedFromServer(StreamRemoteCall.java:303)
	at sun.rmi.transport.StreamRemoteCall.executeCall(StreamRemoteCall.java:279)
...
Caused by: java.lang.OutOfMemoryError: Java heap space
	at org.jetbrains.kotlin.incremental.storage.ProtoMapValueExternalizer.read(externalizers.kt:63)
	at org.jetbrains.kotlin.incremental.storage.ProtoMapValueExternalizer.read(externalizers.kt:48)
	at com.intellij.util.io.PersistentHashMap.doGet(PersistentHashMap.java:616)
	at com.intellij.util.io.PersistentHashMap.get(PersistentHashMap.java:560)
	at org.jetbrains.kotlin.incremental.storage.CachingLazyStorage.get(CachingLazyStorage.kt:64)
	at org.jetbrains.kotlin.incremental.IncrementalJvmCache$ProtoMap.get(IncrementalJvmCache.kt:307)
	at org.jetbrains.kotlin.incremental.IncrementalJvmCache.getModuleMappingData(IncrementalJvmCache.kt:267)

Isn't map.getOrPutBroken? Maps support null values, but getOrPut calls the lambda if there is a null value for a key