OnCreateOptionsMenu doesnt work in second activity Hi, I have two activities, in first one (main) I have a menu working perfect, then, I want to call the second activity (at the moment both have the same code) and the menu is not working… override fun onCreateOptionsMenu(menu: Menu?): Boolean { val inflater = menuInflater inflater.inflate(R.menu.menu_crud, menu) return super.onCreateOptionsMenu(menu) } They are extending AppCompatActivity(), I have no idea why it is not working if the code is a copypaste between them, simply...

Coroutines: Dispatchers.IO only for blocking IO? Hi, I have a code which combines blocking IO and async HTTP requests. Currently I enclose blocking IO inside withContext(Dispatchers.IO) { // use InputStreams coming from async HTTP requests // eg. ZipInputStream(resp.content.toInputStream()).nextEntry } but it’s a lot of work and you can easily forget to do it. Why not use Dispatchers.IO for both blocking IO and async HTTP requests? 1 post - 1 participant <a...

Does returning an object expression (sometimes?) leak a reference to the outer class instance? A method (fun) returns an implementation of a simple interface, which necessarily references a member of the outer class. It’s more concise and readable to write it (contrived): class A(val x: Int) { fun foo(): Interfoo { return object: Interfoo { override fun meth() = x } } } But to (maybe?) avoid the anonymous object maintaining a reference to the instance of class A, I could implement fun foo differently: fun foo(): Interfoo { class B(val x = x): Interfoo {...

Kotlin properties in Thymeleaf templates with Spring EL I have a class with the property var isDone: Boolean but if I reference it in a Thymeleaf template … or if I name the property isIsDone and use isDone in the template. Why does isDone doesn’t work although it meets the bean convention? Is there a simple solution (like the Kotlin extensions for Jackson)? 1 post - 1 participant Read full topic

Ktor REST Repositories for MongoDB Hello Kotlin community! I’d like to present my Ktor Feature for building REST repositories backed by MongoDB! It’s still in early development but it works quite well. I am building it for work so expect it to improve over few months! The documentation is quite lacking, I will add some in the coming weeks! Please use it and report as many problems as you can! Also, thanks for reading 1 post - 1 participant <a...

Packages and file facades are not yet supported in Kotlin reflection This topic’s been discussed before, but there’s been no new movements in any of the other threads for several years, and none of them are ‘pure’ discussions of the language limitation itself. I have a need to access top-level declarations in a Kotlin file through reflection (classes ending in Kt). I.e.: package example val foo = listOf() For my use case, I need to obtain a KType of foo as I need access to the generic parameters, something that’s not well-supported by native Java...

Suggestion: Static local variables C has static local variables, e.g.: int count() { static int count = 0; count++; return count; } This feature leads to much more concise code, the equivalent in kotlin would be: var count = 0 fun count() { count++; return count; } In kotlin, this unecessarily polutes the classes namespace, leads to problems with variable name clashing, and can give the impression that the variable is applicable to the whole class, when in fact it is only applicable to the function....

Would love to see a .when extension added to the language I have mentioned this before but it would be nice to have .when expression in the language as in someResult.when { success -> a() someCondition() -> b() else -> c() } This is just syntactic sugar for this, but I think it is clearer: someResult.run { when { success -> a() someCondition() -> b() else -> c() } } Unlike many other features thus is not something you can create in an extension without language changes 1 post - 1 participant...

How to get a code coverage report for Kotlin/JS Does anyone have a solution for generating a code coverage report for the Kotlin/JS portion of a Kotlin MultiPlatform project? 1 post - 1 participant Read full topic

java.lang.VerifyError occurs. How do I fix it? I got java.lang.VerifyError when I used some operator functions. I don’t know why this error occurs. Could you tell me how to fix it? Error log: Picked up JAVA_TOOL_OPTIONS: -Djava.io.tmpdir=/home/ubuntu_dev/.var/app/com.jetbrains.IntelliJ-IDEA-Community/cache/tmp/ Error: A JNI error has occurred, please check your installation and try again Exception in thread "main" java.lang.VerifyError: Bad type on operand stack Exception Details: Location:...

DSL Scope Limiting with two different DSLs Hey guys. In KorGE we have two different DSLs, one for view building and other for vector building. Something like this: stage { container { // views DSL circle(Colors.RED, 0, 0) // views DSL graphics { // views DSL fill(Colors.RED) { // vector DSL circle(0.0, 0.0, radius = 16.0) } } } } We have a Container.circle function and a VectorBuilder.circle function. I have tried several approaches to limit the scope of those functions like so inside the fill {} block we only...

Display a random layout in Kotlin I am trying to create an app that display random challenges in different levels of difficulty to build a gamified self-development app. As i am a pretty unexperienced developer(this is my first app that is not part of any course), I didn’t used fragments but i actually created a layout that correspond to every challenge. In my app, i am displaying as MainActivity the different levels of difficulty which are represented by buttons. Each of those level button create an intent to an introductory...

Jetbrains annotations 13.0 source download jetbrains annotations 13.0 is a dependency of kotlin I want to get the source for our (Oracle Corporation) internally built repo. -There is source on mvnrepository https://mvnrepository.com/artifact/org.jetbrains/annotations/13.0 - Might not be clean enough (ie download from github/vendor) it does not have a LICENSE.txt I checked one of the source files it has an apache2 copyright header:...

Compiler is nuts! Syntactic issue or misunderstanding of a concept? (topic withdrawn by author, will be automatically deleted in 24 hours unless flagged) 1 post - 1 participant Read full topic

Flutter for UI, Kotlin for the rest Hello all, I know similar questions have been around and perhaps I will annoy many but I really need a professional advice. I want to develop an app for both Android and iOS and have knowledge of Kotlin. But it is clear Kotlin alone will not ample. Two ways are available: Kotlin MP + Swift in xCode (Swift must be learnt) Flutter (Dart must be learnt) I think of third way, namely, Flutter for UI and the business logic with KMP. But the question is: Is there any decent way to realise this...

Function “onButtonClicked” is never use I have created a function called “onButtonClicked” and I don’t want to use a setOnClickListener because I am practicing with different views the problem is when I create the onButtonClicked function, I see this warning `(the “onButtonClicked” function is never used) My code: XML Mainactivity fun onButtonClicked(view: View) { if (view.id == R.id.bt301_tw) { val intent = Intent(this, MainActivity_04_ReadioGroup::class.java) startActivity(intent) } }...

How do i fix “Job was Cancelled” exception? In my Fragment, I’m trying to fetch data from Firebase Database using coroutines where data is retrieving properly. Here is my code @ExperimentalCoroutinesApi //Fragment Class code override fun onStart() { super.onStart() checkOutViewModel.viewModelScope.launch { try{ if (isActive){ checkOutViewModel.getCartDataFromFirebaseNetwork().collect{ tempList.add(it) } } }catch (ex : Exception){...

Give This YouTrack Issue A +1 If You'd Like Enhanced If Statements https://youtrack.jetbrains.com/issue/KT-40222 3 posts - 2 participants Read full topic

Webpack watch in Ktor/Js project I have project with JVM server and JS client and I use gradle to build it. I noticed that webpack is being used for compiling JS. How can I use webpack watch mod for automatically rebuilding only front-end (React)of my project? 1 post - 1 participant Read full topic

Better support for other IDEs Kotlin works very well on Android Studio and Intellij Idea, I love Kotlin, however the use in IDEs like Eclipse, NetBeans and Editors like VS Code and Atom is very very bad, does Jet Brains work on offering better Support for this platform? Will we have Kotlin in use in Scene Builder, Window Builder? Thanks. 1 post - 1 participant Read full topic

Type-safe GraphQL for Kotlin Hey guys. I’ve recently enabled the Manifold Java compiler plugin for use with Kotlin and other JVM languages. I’ve got a sample Kotlin application that could use some more experienced Kotlin eyeballs for review and comment. The application’s focus is GraphQL, however its purpose is to demonstrate how Kotlin can...

Interfaces Implementation by delegation Running this block of code results on the following error: “Class ‘Builder’ is not abstract and does not implement abstract member public abstract var coScope: Float? defined in IData0.Builder” interface BundledActionArgs { interface Builder { fun build(): BundledActionArgs } } interface ICoScope: BundledActionArgs { val coScope: Float interface Builder { fun build(): BundledActionArgs } } class CoScope( override val coScope: Float ): ICoScope {...

Null check in do while loop fun main() { var count = 2 do { val abc = if (count == 0) {null} else {Test(true)} if (abc == null) { break } count-- } while(abc.isOk && count >=0) } data class Test(var isOk: Boolean) When compile above code, I got the following error Only safe (?.) or non-null asserted (!!.) calls are allowed on a nullable receiver of type Test? in } while(abc.isOk && count >=0) But there is already a null check break inside the loop, why cannot...

Interfaces Implementation by delegation, solving the diamond problem Hi is there a way to solve the diamond problem with delegation? getting crazy trying different solutions and can’t find a way to have the last object to behave properly: Here’s my test code: interface C { var a: Int } class Ci : C { override var a: Int = 1 } interface A: C { //var a: Int val f: String } interface B: C { //var a: Int val g: String } class Ai(ci: Ci = Ci()): A, C by ci { override val f: String = "class A" } class Bi(ci: Ci = Ci()): B, C by ci {...

Connecting to sqlserver using kotlin and gradle Hi I had difficulty connecting to MS SQL Server in kotlin using gradle earlier today. I do not know if it is appropriate to post this here but I worked out a solution and thought that it might be helpful to others. As a starting point, because of earlier issues, I had removed all instances of Java greater than version 8 from my computer. First, relevant sections of build.gradle repositories { mavenCentral() } sourceCompatibility = 1.8 targetCompatibility = 1.8 dependencies {...

[Question] Close stream InputStream.readBytes() Hi! I noticed that the extension readBytes from InputStream is not closing the ByteArrayOutputStream. Why not? Reads this stream completely into a byte array. Note: It is the caller's responsibility to close this stream. @SinceKotlin( "1.3" ) public fun InputStream.readBytes(): ByteArray { val buffer = ByteArrayOutputStream(maxOf ( *DEFAULT_BUFFER_SIZE , this.available())) copyTo(buffer) return buffer.toByteArray() } And internally copyTo says that is caller’s responsible to...

Improve smart casting by "dragging a value" along with a new "&gt;:" drag operator Consider a simple example in which smart casting doesn’t work. class MyClass { var name: String? = null fun isNameEmpty(): Boolean { return (name != null) && (name.isEmpty() || name.toLowerCase() == "empty") } } Obviously smart casting doesn’t work in the latter part of the test and this code doesn’t compile. One can solve this in various ways, for example with !!: fun isNameEmpty(): Boolean { return (name != null) && (name!!.isEmpty() || name!!.toLowerCase() == "empty") } but...

Problem with resolution of spring's @RequestParam with Kotlin Hi, in Java You can either call ?params=1,2 or ?params=1&params=2 no matter if your request param is declared using @RequestParam List params inside signature of controller method, or it is a field of external class that’s used to group all request params of controller method. In Kotlin if you declare your request param inside of controller method signature, as a @RequestParam params: List you can call it using both methods, so: ?params=1,2 and ?params=1&params=2 If you however, extract it to...

Initializing object declarations with arguments? I have a singleton that needs a parameter to initialize itself. I can provide that parameter during application startup, but I’m not sure how to code it. Is it possible? object MySingleton { lateinit var arg: Thing private val foo = getFooDependsOnThing(arg) var bar: String by someDelegate(arg) } Or should I just do something like this? class MySingleton(arg: Thing) { ... companion object { lateinit var shared: MySingleton } } // and on app startup......

Handling Etags on the client side I’m trying to find some ideas on how to handle Etags on the client-side from within Webflux http client builder( WebClient.Builder ) Wondering if it would build the response based on the server’s response(cached payload if 304 or a new one if 200). Something similar to the way that Retrofit2 does. Anyone? e.g. public static Retrofit getAdapter(Context context, String baseUrl) { OkHttpClient.Builder builder = new OkHttpClient().newBuilder(); builder.cache( new Cache(context.getCacheDir(),...