I’m getting this with IDEA 2018.1 EAP, Kotlin 1.2.30

Hello, World! Hey, when doing sealed classes, the compiler complains that the types can only be subtypes of the sealed class. Does that mean that the one example on the official doc is wrong?

Why isn’t this legal?

class Foo<Bar>(
        initial: Bar?
) {
    
    private val internal: Any? = initial
    
    fun baz(): Bar? {
        val i = internal
        return if (i is Bar) i
        else null
    }
}

Error: Cannot check for instance of erased type: Bar

I have two methods:

fun <T> bind(type: Class<T>, instance: T)
fun <T> bind(type: Class<T>, factory: Function<T>)

Calling it like this fails with "Cannot choose among the following candidates without completing type inference":

bind(MyClass::class.java, { p: String -> MyClass(p) })

Why is this? Using a reference instead of a lambda (

bind(MyClass::class.java, ::MyClass)

) works fine. What am I missing here?

Hello Im not sure if this is my fault, or a actual bug in the Kotlin Compiler. In the main function, the first thing i am doing is replacing the System.out with a own class(Java). Afterwards i am only invoking thoose methods:

fun main(args: Array<String>) {

    System.setOut(SprummlbotOutStream())

    System.out.println("Test System.out.println()")
    println("Test println")
    

}

Thats the output:

[12.3.2018 00:26:40 | INFO] Test System.out.println()
Test println

Process finished with exit code 0

SprummlbotOutStream

public class SprummlbotOutStream extends PrintStream {

    public SprummlbotOutStream() {
        super(System.out);
    }

    @Override
    public void println(String msg) {
        Calendar cal = Calendar.getInstance();
        SimpleDateFormat sdf = new SimpleDateFormat("d.M.Y HH:mm:ss");
        if (!msg.startsWith("["))
            msg = " " + msg;
        super.println("[" + sdf.format(cal.getTime()) + " | INFO]" + msg);
    }
}

My question: why does println use the old stream? Kotlin pl: 1.2.30 JDK: 1.8.0_162

i'm jumping to

python

from time to time. and sometimes trying to bring python syntax into kotlin. probably i must be shot for such things anyway 🙂

How about this:

val (a, b, c) = line.split("\t") + listOf(null, null, null)

sometimes I got

ConcurrentModificationException

so then so how can I change my

MusicStore

object to make it safe from errors/race conditions ? do I need to change type of

lists

does anyone know a map class where the

Entry

objects stay valid when the backing map is modified? I want to hold on to the

Entry

object so I don't have to access the map every time when all I need is that one entry

I just installed the latest Kotlin 1.2.30 IntelliJ plugin and upgrade my Gradle build files accordingly. Now my IDE is throwing an exception every few seconds and my auto-completion support is gone 😞. Anyone else having this issue? Exception stacktrace incoming

Hi, I am trying to compile a multiplatform project (only a common and a jvm module atm) using the Arrow library. IDE completion in Idea worked fine, but compiling fails with "Unresolved reference" errors for the stuff I used from Arrow. Is Arrow compatible with common-modules or is this caused by something else?

I could pass a

Class<T>

into the exception.

I’m baffled. And the bytecode viewer is not helping because it throws an exception 🙂

listOf

will create an immutable list

/**
 * Returns an immutable list containing only the specified object [element].
 * The returned list is serializable.
 * @sample samples.collections.Collections.Lists.singletonReadOnlyList
 */
@JvmVersion
public fun <T> listOf(element: T): List<T> = java.util.Collections.singletonList(element)

@nickk you could create your own List-Type and use delegation

class MyImmutableList<T>(private val list: List<T>): List<T> by list

then the user won't be able to cast your list into a

MutableList

and therefore won't be able to edit it

Seems abandoned

What is the good way to make two fields, that are calculated from each other? Here is example that don't work: https://pastebin.com/pTGnX947

Hey guys, realm or objectBox? comments?

@nkiesel looks like an initialization order problem. probably worth a youtrack issue.

I cant

@JvmName("dotFloat")

methods in `interface`s?

Hey everyone. I'm looking for a concurrent.Semaphore but for coroutines. Does such a thing exist?

is there existing issue for

collection literals

feature? can't find it on the tracker

you could do this, but this is ugly as hell: 😈 :java: ❗❗

data class Person(val name: String, val age: Int) {
	init {
		Person::class.memberProperties
			.find { it.name == "name" }
			?.javaField
			?.let {
				it.isAccessible = true
				it[this] = "${it[this] as String}suffix"
				it.isAccessible = false
			}
	}
}

How to delete element from array in kotlin ? can u give me simple example ?

#codereview would be a better place for bikeshedding though 😉

New to Kotlin. Is Spek used as much as Spock is in the Groovy world?