is equality for maps just checking the object reference, or is it seeing if they contain the same data

If you need instances, that sounds more like sealed classes than enums

can someone explain or point documentation what is the reasoning behind that using return in list.map { return xxx } is not actually return of value of the lambda function? and what is the use case where this return behavior would be useful?

Assign it to a local val first

beautiful. Thanks!

what is the Kotlinish way to solve this?

well, i used

<http://handler.post|handler.post>(object: Runnable{
        ...
        })

and this works. Thanks a lot!

Hi there fellas, I'm currently experimenting on kotlins standard lib functions, especially on use(). Unfortunately I'm still not sure how it works in case of an Exception being thrown. I have this function that writes a File to my apps storage:

fun writeSoundToSharedStorage(context: Context, sound: ISound): Boolean {

        var inputStream: InputStream? = null
        var outputStream: OutputStream? = null
        val targetFile = getTargetFileFromSoundName(sound.soundName()) ?: return false

        try {

            inputStream = context.assets.open(getAssetPathFromSound(sound))
            outputStream = FileOutputStream(targetFile)
            inputStream.copyTo(outputStream)
        } catch (ex: IOException) {
            Log.e(LOG_TAG, "Failed to save file: ${ex.message}")
            return false
        } finally {
            try {
                inputStream?.close()
                outputStream?.close()
            } catch (ex: IOException) {
                ex.printStackTrace()
            }
        }
        return true
    }

What I'm thinking about is to migrate the try-catch-finally-block to a use()-block. But from the docs of use() I'm not sure if exceptions are handled or not. I took a look into the implementation and for me it looks like an exception is thrown, so my guess would be that my app would crash as long as I don't handle it somehow. Also my function depends on returning false if something went wrong. It would be nice if someone could bring some more clarity to me 🙂

Hello all

class MapBuilder<T,U> {
    operator fun invoke(arg: T): MapBuilder<T, U> {
        return this
    }
    operator fun invoke(arg: U): MapBuilder<T, U> {
        return this
    }
}

of course it's don't work due to JVM limitations. Platform declaration clash: The following declarations have the same JVM signature

(invoke(Ljava/lang/Object;)Lcom/test/tests/MapBuilder;):
    operator fun invoke(arg: T): MapBuilder<T, U> defined in com.test.tests.MapBuilder
    operator fun invoke(arg: U): MapBuilder<T, U> defined in com.test.tests.MapBuilder

Any ideas how can I realize this?

What if I have a

MapBuilder<String, String>

?

Hello. I’m new to Kotlin. I’ve created an empty Kotlin project from this instruction https://kotlinlang.org/docs/tutorials/getting-started.html , but I don’t have run button in Project. Could you give me an advice

thanks, it works now. Can I add coroutines library easily? In empty project I don’t see gradle files

Does building with gradle work?

Hello guys, what does it mean? “‘get(String, HttpRequestBuilder.() -> Unit = ...): T’ is deprecated. Experimental coroutines support will be dropped in 1.4” . I’m using ktor framework + coroutines and ktor methods are highlighted as deprecated

I can't get Kotlin to run on a fresh project with IDEA. When I mark /src as Sources Root, I get the message "Kotlin not configured" above the file. No idea whats going wrong

is it pretty common for people to have there own mutable types for private use in a system, then having a immutable version of the same type for exposing that object publicly?

Can someone advice kotlin library for parsing html? Desirably multiplatform kotlin library

What does it mean if there is a lambda with a nullable receiver?

this

can == null in the body of the lambda?

fun foo(block: String?.() -> Unit)

vs

fun foo(block: String.() -> Unit)

I noticed that with the second I cannot call

.block()

on a

String?

but the lambda body (for block param where foo is used) stays the same.

Does it (::update) produce new lambda on each invocation like in Java or it's cached somewhere?

Well, I have also vim-plugin, so it's an extra problem to find shortcut (trial and error) + window manager grabs all

Cmd+...

shortcuts

Sorry for stupid question - how to get the size of sequence? I’ve looked through the whole doc and can’t find https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.sequences/-sequence/index.html

Hello, I'm a beginner. Please help. Where can be a bug? Thank you

is there method in kotlin that allows to unescape html chars? E.g convert ' -> ' , & as &(ampersand), % as % and so on

I'm planning on making a Kotlin library for core Android logic of apps. Is there a gradle plugin/distribution playtform any of you can recommend?

Hi, I have a styling question related to data classes and copy method.

val connectionUri = "jdbc:postgresql://$host:$port/$database?user=$username&password=$password"

val connection = PostgreSQLConnectionBuilder.createConnectionPool(connectionUri) { it.copy(
        connectionCreateTimeout = 1
)}

I am writing a lib and I want to configure a connection. Configuration is a data class and all are vals. Can I avoid the

it.copy

in the code above (call the copy somehow in the lib), or is there an apply method?

Should we use

hashSetOf<X>()

or

HashSet<X>()

for when we want a mutable hash set?