Did I just find a bug with the Kotlin compiler? The following example throws an error at line 4:

'if' must have both main and 'else' branches if used as an expression

fun exampleFunc(someBoolean: Boolean) = when (someBoolean) {
    else -> {
        val otherBoolean = Random.nextBoolean()
        if (otherBoolean) {
            print("Yay!")
        }
    }
}

It seems to think it is a ternary, I guess.

Is there an appropriate channel to share information about a webinar geared towards Android developers? My company, Embrace, allows mobile teams to go from a Google Play Store review directly to inspecting the user session where the issue occurred. We have a webinar showing this feature, and I'd like to share but also do not want to spam if it's inappropriate.

I am new to agile method, if my PM set a feature to be 4 story points, it means that it takes 1 individual to complete it in 4 story points or it takes the whole BE team to complete in 4 story points?

is there a function for

?:

similar to how there's

get()

for

[]

? if not, why not ?

https://kotlinlang.org/docs/shared-mutable-state-and-concurrency.html#volatiles-are-of-no-help It says here that volatiles do not provide atomicity of larger actions like increments. Increments is the smallest action i can think of. Does that mean volatiles has zero value? is this only in the case of coroutines or also in the case of threads?

Is there any way to force return true here in a debugger?

I’m pretty stuck on something, getting the following failure on a micronaut test

Failed to inject value for parameter [client] of class

I’m trying to inject a client in the constructor of a

StringSpec

test

@Client(value = "/") private val client: RxHttpClient,

I just can’t work it out.

This message was deleted.

is it normal that if I want to implement the following gradle interface

public interface ArtifactRepository {
    String getName();
    void setName(String name);

I cant use a

override var name: String

, but I'm forced to

class GithubArtifactRepository : ArtifactRepository {
    private var n = "github"
    override fun getName(): String = n
    override fun setName(name: String) { n = name }

Want some fun? Compile the following code and watch your 1.5.0 compiler burn and crash 😄 (already created an issue)

interface A {
    fun a(): String = bu
        "test ${unresolved}"
    }
}

Hello, I use this class in my tests:

interface TaskA

class TaskWithExceptionInInitializerError : Task(), TaskA {
    companion object {
        @JvmStatic
        val e: Nothing = throw Exception("ExceptionInInitializerError")
    }
}

Of course this task is written to trigger an Exception during instantiation. I had no issue with Kotlin 1.4.30, but with 1.5.0, it does not compile, with following error:

org.jetbrains.kotlin.backend.common.BackendException: Backend Internal error: Exception during code generation
...
Caused by: java.lang.RuntimeException: Exception while generating code for:
FUN JVM_STATIC_WRAPPER name:getE visibility:public modality:FINAL <> () returnType:kotlin.Nothing
  EXPRESSION_BODY
    BLOCK type=kotlin.Nothing origin=null
      CALL 'public final fun <get-e> (): kotlin.Nothing declared in io.infinitic.config.tasks.TaskWithExceptionInInitializerError.Companion' type=kotlin.Nothing origin=null
        $this: GET_FIELD 'FIELD FIELD_FOR_OBJECT_INSTANCE name:Companion type:io.infinitic.config.tasks.TaskWithExceptionInInitializerError.Companion visibility:public [final,static]' type=io.infinitic.config.tasks.TaskWithExceptionInInitializerError.Companion origin=null
      CALL 'public final fun throwKotlinNothingValueException (): kotlin.Nothing declared in kotlin.jvm.internal.Intrinsics' type=kotlin.Nothing origin=null

	at org.jetbrains.kotlin.backend.jvm.codegen.FunctionCodegen.generate(FunctionCodegen.kt:54)
	at org.jetbrains.kotlin.backend.jvm.codegen.ClassCodegen.generateMethodNode(ClassCodegen.kt:338)
	at org.jetbrains.kotlin.backend.jvm.codegen.ClassCodegen.generateMethod(ClassCodegen.kt:353)
	at org.jetbrains.kotlin.backend.jvm.codegen.ClassCodegen.generate(ClassCodegen.kt:128)
	at org.jetbrains.kotlin.backend.jvm.JvmIrCodegenFactory.doGenerateFilesInternal(JvmIrCodegenFactory.kt:206)
	... 35 more
Caused by: java.lang.AssertionError: IrCall expected inside JvmStatic wrapper:
FUN JVM_STATIC_WRAPPER name:getE visibility:public modality:FINAL <> () returnType:kotlin.Nothing
  EXPRESSION_BODY
    BLOCK type=kotlin.Nothing origin=null
      CALL 'public final fun <get-e> (): kotlin.Nothing declared in io.infinitic.config.tasks.TaskWithExceptionInInitializerError.Companion' type=kotlin.Nothing origin=null
        $this: GET_FIELD 'FIELD FIELD_FOR_OBJECT_INSTANCE name:Companion type:io.infinitic.config.tasks.TaskWithExceptionInInitializerError.Companion visibility:public [final,static]' type=io.infinitic.config.tasks.TaskWithExceptionInInitializerError.Companion origin=null
      CALL 'public final fun throwKotlinNothingValueException (): kotlin.Nothing declared in kotlin.jvm.internal.Intrinsics' type=kotlin.Nothing origin=null

	at org.jetbrains.kotlin.backend.jvm.codegen.IrCodegenUtilsKt.isAccessorForDeprecatedJvmStaticProperty(irCodegenUtils.kt:364)
	at org.jetbrains.kotlin.backend.jvm.codegen.IrCodegenUtilsKt.isDeprecatedFunction(irCodegenUtils.kt:348)
	at org.jetbrains.kotlin.backend.jvm.codegen.FunctionCodegen.calculateMethodFlags(FunctionCodegen.kt:184)
	at org.jetbrains.kotlin.backend.jvm.codegen.FunctionCodegen.doGenerate(FunctionCodegen.kt:59)
	at org.jetbrains.kotlin.backend.jvm.codegen.FunctionCodegen.generate(FunctionCodegen.kt:52)
	... 39 more

Any idea, how to avoid this?

Hi there! Tried Kotlin 1.5.0 today. When running the tests in one particular backend I get this exception:

java.lang.ClassCastException: class [[Ljava.lang.Object; cannot be cast to class [[Ljava.lang.String; ([[Ljava.lang.Object; and [[Ljava.lang.String; are in module java.base of loader 'bootstrap')
	at edu.upc.groups.service.adapter.GroupTemplateApi$$serializer.deserialize(GroupApiRestDomainMapping.kt:75)
	at edu.upc.groups.service.adapter.GroupTemplateApi$$serializer.deserialize(GroupApiRestDomainMapping.kt:75)
	at kotlinx.serialization.json.internal.PolymorphicKt.decodeSerializableValuePolymorphic(Polymorphic.kt:63)

The serializable class is (working perfectly in previous Kotlin version)

@Serializable
internal class GroupTemplateApi(
    val id: String,
    val expression: String,
    val attributes: Array<String>,
    val records: Array<Array<String>>,
    val owner: Int,
)

What do you thing, I should file a bug? Kotlin? Serialize library? I already tried to clean and reset caches.

I have a puzzling behavior:

import kotlin.time.*

class MyClass {
   // ...
    private var _timeSource = TimeSource.Monotonic
  // ...
}

results in

Unresolved reference: TimeSource

If I use

private var _timeSource = kotlin.time.TimeSource.Monotonic

, then it is fine. Any idea?

why can't interfaces inherit from classes ?

why do interface members have to be public ?

that’s disappointing

Question: When are flow apis like

flattenMerge

going to be "stable"? Whe are now in coroutines 1.5.0 and it still needs to be annotated with @ExperimentalCoroutinesApi

So the release of Kotlin 1.5 finally unlocks the use of

Result

by default! I was surprised to find this out given how quiet this change was. Using

Result

as a return type for libraries and in general seems like a great middle ground between the looseness of unchecked exceptions and the verboseness of sealed classes as return types. You can force callers of your method to handle any failure by simply doing

fun method(): Result<T> = runCatching { ... }

, allowing uncaught exceptions in the method to bubble up into the failure case of the result. This is much less code than creating a sealed class for every failure case and writing the logic to convert each exception to them. Easier to read and reason about, and doesn't even force you to adopt functional-style-programming. Now that this is doable with vanilla Kotlin, what does everyone think? Would you adopt this as your default way of error handling? How would you feel consuming a library that exclusively used

Result

instead of throwing exceptions?

is there any way to achieve this behavior without the compilation error?

Hi, I have a question, does Kotlin has better performances than Java at execution ?

Is there a compiler flag to disable auto generated componentN for data classes?

Hello, I've been having a very strange problem. Kotlin does not find a field in an anonymous object.

val man = object : ScriptEngineManager(Thread.currentThread().contextClassLoader) {
	val engine: ScriptEngine inline get() = getEngineByExtension("kts")!!
}

When I try to do

man.engine

, it says

Unresolved reference: engine

, as if it's not there at all. It's very strange. The weirdest thing, is that if I take that code, and copy-paste it into my function, so that

man

is a local variable, it works fine. But if I have it as a field, I cannot access

engine

and I don't know why. There are no naming conflicts with the superclass.

IDEA generates

equals

and

hashCode

(for class

A

) with violating

hashcode

contract. Is it bug, or am I wrong?

I remember reading about a way to benchmark our code using Kotlin Duration classes, I can't find it back. I know there is measureTime, measureTimedValue, but it execute in a block and I'm pretty sure there was a way to do it outside of a block, or by calling a method to "mark" moment of time (like start and stop), does anybody know wha I'm talking about ?

I have a variable called

dec31_2015

in Java. How should I name that in Kotlin? I get this warning about the underscore.

Is this new in Coroutines 1.5.0?

Hello everyone, I have been learning kotlin for about a month, I want to contribute to open source libraries so that I can learn kotlin best practices and new things. Can anyone please suggest some good beginner friendly open-source project. P.S. I don't want to work on android apps I want to work on some generic libraries.

Hi everyone. I’m from python and I’ve been learning kotlin for about a month as well. As using Kotlin, I’m getting understand the syntax but don’t get how to design well OOP yet. Can anyone please suggest book recommendation or related materials? Thanks!

Why won't this work? LegalMenu is an enum.