Hi, is there any tutorial on how to work with multiple gradle modules ?

Is it not possible to save a lambda parameter from a inline function to a variable? This doesn't work:

@PublishedApi
internal var onFinish = {}

inline fun onFinish(action: () -> Unit) {
    onFinish = action
}

What is the best way to compare two classes of the same type, and copy all the properties of the second one that are different compared to an original? For example, let's say I have 3 string variables stored in said class:

class SomeClass {
    var string1: String = "Default"
    var string2: String = "Default"
    var string3: String = "Default"
}

and lets say in the first class,

string1

is "Text,"

string2

, is "Other Text," and in the second class

string1

is "String, " while

string2

is still Default I would want it so that the first string is "String," the second string is "Other Text," and

string3

as "Default"

Hello all! I want to ask if anyone knows any good resource to start with Compose/Jetpack, thanks!

Hey guys, do we need to await for the result returned by a suspended function ?

runblock {
val result =  methodCall(). // this method is suspended 

repository.persistResultToDB(result)
}

so, the

methodCall()

do we need to await for its completion, to be able to use the returned

result

to persist them to the db ?

Hey I was using this approach: (thread) to split my seconds into minutes and seconds. However if I get seconds > 3600 this one doesn't work anymore as seen in the picture. Anyone got a better solution?

e.g.

fun <T> bar(): T { 
    error("")
    return "" as T
}

fun foo() {
    if (true) {
        1
    } else {
        bar()
    }
}

This works - bar can be invoked, because it infers to int. But if you unwrap the if statement, suddenly the return type of bar can't be inferred anymore (the contents of bar aren't important here, this crops up no matter what it contains).

whats the best practice for non-spring oriented singleton retrieval if you know interface? ``````

Hello, I don't know how to call this Java code from Kotlin:

public static Document parse(File file, @Nullable String charsetName) throws IOException {
        return DataUtil.load(file, charsetName, file.getAbsolutePath());
    }

when I call this code from Kotlin,

val document = Jsoup.parse(inputHTML, null )

I get

Kotlin: Null can not be a value of a non-null type String

How can I call this with Java type null, since parameter is @Nullable and therefore Null should be accepted.

I'm messing around with the new context receivers and I'm seeing what appears to be an issue, but I figured I'd ask here to make sure I'm not just doing something wrong. (see thread)

Why is kotlin showing me: 1.49262774E8 and not 149,262,774?

If I have

val data =
    hashMapOf(
            "firstName" to firstName,
            "lastName" to lastName)

but I wanted to not add firstName or lastName to the hashmap if they are null. What would be the best way to do that?

hey lads, can I make a for loop on a tuple of two list of the same size?? or a for loop on two sets of list

Hi everyone! I have a rather strange situation: I am testing my library with JUnit (as it was in many guides) and they are working correctly on my local machine, but on Github Actions they fail with really strange exception:

Caused by:
        org.opentest4j.AssertionFailedError: Array elements differ at index 0. Expected element <Lesson(place=4, timeConstraints=TimeConstraints(startHour=11, startMinute=25, endHour=12, endMinute=10), title=Биология, classID=8, teacherID=104631, journalID=null)>, actual element <Lesson(place=4, timeConstraints=TimeConstraints(startHour=11, startMinute=25, endHour=12, endMinute=10), title=Биология, classID=8, teacherID=104631, journalID=100125)>.
        Expected <[Lesson(place=4, timeConstraints=TimeConstraints(startHour=11, startMinute=25, endHour=12, endMinute=10), title=Биология, classID=8, teacherID=104631, journalID=null)]>, actual <[Lesson(place=4, timeConstraints=TimeConstraints(startHour=11, startMinute=25, endHour=12, endMinute=10), title=Биология, classID=8, teacherID=104631, journalID=100125)]>.

The most bizzare part of that assertion fail is part with

journalID=null

in expected element. The problem is that there are no null journal ID's in tests. Does anybody know what is my problem? Source code for tests (the failing one is marked): https://github.com/Neitex/Schools_Parser/blob/74c9fb9ed14b47cce4d173dc288d0a91a088b3ed/src/test/kotlin/com/neitex/SchoolsByParserTest.kt#L430 Source code of Lesson constructor (this is a regular data class, nothing special): https://github.com/Neitex/Schools_Parser/blob/74c9fb9ed14b47cce4d173dc288d0a91a088b3ed/src/main/kotlin/com/neitex/DataClasses.kt#L63 Thanks in advance!

Is there a good way to have object "inherit" each other? Explanation in thread.

Is there a built-in to give me stats about a collection of numbers? E.g. avg, min, max at the same time?

val map = getMapOfDataFromOutside()
val homeCountry = map["Home Country"] ?: error("Data table is missing 'Home Country' entry or its key is incorrect")
val homeCity = map["Home City"] ?: error("Data table is missing 'Home City' entry or its key is incorrect")

Hi. I have this map and I handle the nullable value by a key with

?: error(…)

. The error message is equal for all entries I’m retrieving except one parameter, so I want to extract this into a separate method to make code shorter:

val homeCountry = map["Home Country"] ?: throwAnErrorForKey("Home Country")
private fun throwAnErrorForKey(key: String) {
    error("Data table is missing '$key' entry or its key is incorrect")
}

With this code, the return type of the

homeCountry

is

Any

and not

String

. How can I extract the

?: error()

part properly?

I've got an error message that I don't understand:

val sqlServerDataSource = SQLServerDataSource()
        sqlServerDataSource.url = myUrl
        sqlServerDataSource.user = myUser
        sqlServerDataSource.password = myPassword

The error is:

Cannot access 'password': it is public/*package*/ for synthetic extension in '<library Maven: com.microsoft.sqlserver:mssql-jdbc:10.2.0.jre17>'

There is no error on url or user; only on password. If I replace it with

sqlServerDataSource.setPassword(myPassword)

it works. But why can't I use the property syntax, and what exactly does the error message mean, and why only password has this error?

Is there anything in Kotlin that would help with formatting a number with a given amount of significant digits (not decimal places)?

I believe I found another bug with context receivers, but before I submit a new bug report, I'd like to do a quick sanity check here to make sure I'm not just making a dumb mistake. Code in thread.

Hi all! Just started learning Kotlin, enjoying it so far! 🙂 I’ve only done some coding via the Kotlin playground but I had a couple of questions. 1. When you have a lamda assigned to a variable, is there a way to get the compiler to say the “name” (the variable name) of a lamda function when errors occur? Right now, I get the below:

// This code
val add: (Int, Int) -> Int = { x, y -> x + y }

fun main() {
    add(1, 2, 3)
}

// Gives me
Too many arguments for public abstract operator fun invoke(p1: List<Int>): List<Int> defined in kotlin.Function1

Versus with a named function

//This code
fun add (x: Int, y: Int): Int = x + y

fun main() {
    add(1, 2, 3)
}

// Gives me

Too many arguments for public fun add(x: Int, y: Int): Int defined in root package in file File.kt

Side note: I don’t know why the former error message has this type annotation for the function (it doesn’t match what my code specifies):

fun invoke(p1: List<Int>): List<Int>

2. Is there a way to type a named function via extracting the types, like you can do with variables + lamda/anonymous functions?

// Lamda with inline type annotations
val add1 = { x: Int, y: Int -> x + y}

// Lamda with extracted type annotations
val add2: (Int, Int) -> Int = { x, y -> x + y}


// Named function with inline type annotations
fun add3 (x: Int, y: Int): Int = x + y

// Named function with extracted type annotations
?

This would be helpful so we could easily share type annotations among functions via a typealias. In addition this is particularly helpful for me because I find it harder to parse type annotations when they’re inlined. And I often like to be able to glance at function types and see if it matches what I need versus having to pick it apart from parameters. Thanks!

Is it possible to have inheritable / abstract inlined functions?

Anyone know why this doesn’t work

val nullableFoo: Any? = null
val nonNullFoo = nullableFoo != null
if (nonNullFoo) {
   acceptsNonNullFoo(nullableFoo) // expected Any but is Any?
}

but this works

val nullableFoo: Any? = null
if (nullableFoo != null) {
   acceptsNonNullFoo(nullableFoo)
}

🤔

Is there a way to call a non-context function from within a context function of the same name?

fun generate(selection: Selection, values: Values) { ... }
context(Scope) fun generate(selection: Selection, values: Values) =
    generate(this@Scope.selection refine selection, values)
       ^ this is a recursive call, but I would like to call the other (non context(Scope)) generate function

I would like to write something like this:

fun test(foo: List<Number>) {
  if (foo.containsOnly<Int>()) {
    val bar: List<Int> = foo
  }
}

Note that I don't want to use

filterIsInstance()

here. Is it possible to write an extension function that allows for this smart-cast?

interface Logger {
   fun log(value:String)
}
context(Logger)
open class A

class B(): A()

Do i need a Logger context to create a object of class B?

why can i do

val x: List<Int> = listOf(1, 2, 3)
val y: List<Number> = x //works fine

but not

val x: Array<Int> = arrayOf(1, 2, 3)
val y: Array<Number> = x //error: type mismatch

?

Hi, this might be a bit unconventional question, but right now i am working on a presentation that should convince leadership that it’s okay for us to use Kotlin. so far the presentation is mostly about addressing/mitigating the risks/concerns involved, but of course I also have to convince people that it is worth taking on those risks. this creates an interesting problem. for me Kotlin does have a huge list of benefits, but due to the time constraints and attention span constraints i can’t really just go ahead and nerd out about them. also the audience is a bit different, have to aim at leadership instead of the developer. so the question is: if you have 3 slides to talk about why how using Kotlin would benefit your manager, which features/benefits would you talk about and why?

Hi, right now i'm trying to build a Design System/UI Package in Kotlin, and i didn't have too much experience of developing in Kotlin, so currently i would like to know if anyone has any resources where i can learn to build one. i have tried to search in many places but haven't found any resources that really match what i wanted to build. here i'll share the of what i wanted to achieve, the Design System in the link was build in Flutter, but it only serves as reference so that you understand what i would like to achieve while developing the Design System in Kotlin(skip to 2:54). i'm sorry before if i referencing other programming language, but this is the only reference of Design System development that i could find.