Is there a way to tell a compiler to open all classes and methods for test compilations?

Hello all, what is the kotlin-native way to stop/kill another process ?

Kinda feel silly but I can't wrap my head around people using different functions to essentially just do a null check. I still find

if (myItem != null) { //do something }

makes sense in kotlin as it does in java. Is using

let{}

really needed? Would someone say that my if statement is not idiomatic? I like to follow the 90 day rule. If I come back to the code in 90 days... which one will I understand? I feel that most would choose the if.

Hello, I have tried to make JPA Entity classes for a Spring Boot - Data Rest project. I worked with data classes, but the Lazy loading not working with them (because they are final?). There is an another way to get toString and hashCode like lombok in java?

Newby question: why was kotlinx.serialization designed as a compiler plugin rather than an annotation processor?

kotlinx.cli is now available ( see https://blog.jetbrains.com/kotlin/2019/11/kotlin-1-3-60-released/ ) .. Is there an example of how to add the dependency in a groovy build.gradle file? Or just add it as a maven/jcenter dependency?

newbie question! Hello! please tell me how can I add char to string?

hello all! can i add var like pattern in Regex? something like

var regWord = word.toRegex

var list = line.split(Regex("""^(regWord)+"""))

i need to count regWord in line

Is there a Kotlin/IDEA thing like Swift Package Manager?

Hello everyone, I’m having a very strange issue. I cannot find BadgeDrawable in my project anywhere? Do I need to add a dependency for it?

What book would you recommend to someone who has decent experience in Java but wants to learn Kotlin? I saw Bruce Eckel is writing a book but it’s not finished yet sadly.

what is the most performant way to access erased types? here's an example where perhaps you want to access it:

iterface Foo : Comparable<Bar> {
    override fun equals(other: Any?) = when (other) {
        is Comparable<*> -> // other is Comparable<Bar> && (other as Comparable<Bar>).compareTo(this) == 0
        else -> false
    }
}

cast as and try/catch?

Does anyone have a good boilerplate setup for solving Advent of Code problems with Kotlin?

This message was deleted.

Hi, Please help me to find out what is the best way to implement thread-safe singleton (for DB connection)? Here are the variants:

object DBProvider {
    @Volatile private var dbSession: Session? = null

    fun getDBSession(): Session = dbSession ?: synchronized(this) {
        dbSession ?: when (dbType) {
            DBTypes.MYSQL.type -> MySqlSession(host = dbHost, port = dbPort).getSession()
            DBTypes.ORACLE.type -> OracleSession(host = dbHost, port = dbPort).getSession()
            else -> throw Exception("Unsupported DB type - $dbType.")
        }.also { dbSession = it }
    }
...

Hi all, I was wondering is there a better way to create

set

or

distinct

lists from a list of objects based on their property? Currently I’m looping through each user and adding them one by one to the

set

val userEmails = mutableSetOf<String>()
users.forEach {
    userEmails.add("Adding unique email: ${it.email}")
}
print(userEmails)

Hi, I'm following the Udacity bootcamp and one of the examples in the lecture doesn't work for me, this is the code:

package aquarium

class Aquarium (var length: Int, var width: Int, var height: Int) {

    var volume: Int
        get() = width * height * length / 1000
        set(value) = {height = (value * 1000) / (width * length)}

This is the warning I'm getting from Intellij for the set(value):

Type mismatch: inferred type is () -> Unit but Unit was expected

I don't understand what is this supposed to signify?

does Kotlin have some kind of index type? for example, I want to pass a List, and an index into that List. I could pass just an Int as the index, but it's possible that is outside the bounds of the list. I was wondering if there was some kind of type-safe way to tie the two together?

I'm having some trouble testing a KClass<T> for being an Enum, and then getting an equivalent to

Class<T Extends Enum<T>>

out of it. for example:

fun <T : Any>test(valueType: KClass<T>) {
    when (valueType) {
        Enum::class -> {
            // How to get 'x' to be Class<T> where T extends Enum<T> ?
            val x = valueType.java
        }
        else -> TODO()
    }
}

Hello! How can I get IntRange of the indexes after slicing the array of bytes? I slice array in this way:

val chunks = data.asIterable().chunked(CHUNK_SIZE)

For example, I need an index (from original array) of first byte in second chunk.

> kotlinc -script .\p2.kts
error: invalid argument: -script
info: use -help for more information

Anyone know why this is happening? I'm on Windows and installed Kotlinc through the zip on the releases page, and when I run

kotlinc -version

it outputs

> kotlinc -version
info: kotlinc-native 1.3.60 (JRE 9.0.1+11)
Kotlin/Native: 1.3.60

-script is not listed in the options specified in -help.

If I have a function that uses as first argument an instance of a class, can I use the dot notation with it? I mean, can I have something like:

fun myFunction (foo :MyClass) { /.../ }

and call it like:

val foo = MyClass( /.../ )

foo.myFunction()

Hi! In java, there is a shortcut for switching the value of a boolean, like this:

myBoolean ^= true

So if it was true, it becomes false and if it was false it becomes true. Is there an equivalent in kotlin?

I'm sure there is an elegant way to convert this

val catalogues = mapOf(
    "de-catalogue" to listOf(29L, 10010L, 10012L, 10013L),
    "fr-catalogue" to listOf(10007L, 10019L, 10020L),
    "nl-catalogue" to listOf(10008L, 10023L, 10024L),
    "it-catalogue" to listOf(10021L),
    "es-catalogue" to listOf(10022L)

into a Map<Long,String> where each list value becomes the key and the key (from the original map) becomes the value

Which is the best way to getting started in the kotlin ?

i have a class in a lib whose constructor is marked as

internal

, but when i include that lib (via a maven dependency) in a java project, i can still access that constructor. am i misunderstanding the scope of

internal

?

I have some ugly code that I’d like to improve. My goal is to create an array

results

as long as the list

neededPermissions

where every element of

results

has the value

PackageManager.PERMISSION_GRANTED

except for a single element. Here’s my code:

val results = neededPermissions.map { PackageManager.PERMISSION_GRANTED }.toIntArray()
results[0] = PackageManager.PERMISSION_DENIED

I know how to do what I want in Scheme (with

cons

and

cdr

). What’s a nice way to do it in Kotlin?

By using delegating properties, first example is the same as the second example without using delegates.

class User(private val map: MutableMap<String, String>) {
    
    val name: String by map
    val lastName: String by map
}

class User1(private val map: MutableMap<String, String>) {
    
    val name: String
    val lastName: String
    
    init {
        
        name = map["name"].toString()
        lastName = map["lastName"].toString()
    }
}

So basically, when accessing property "name" from class User in the fun main(). It is using MutableMaps default getValue() implementation to get the value?

Hello! How to use data from File in Kotlin and delete the information after? I get OutOfMemoryExcetion. I send data every 5 seconds from the File to the server. The data all the time is updated. Then need to remove the data. Now I have this :

val bytes = fileOut.readBytes().sliceArray(range)

And then I send the bytes. I do nothing with this after. As I understand JVM garbage collector should clean this data myself after a while but does it not always. I google this, I think I can use something like try-with-resources in Java -

use

. But this extension is unable for the Class. Do you have some advice for me? Thanks.

What naming convention do you use for a situation like this: