Anko button onClick not working I'm fairly new to Kotlin, and I'm using Anko DSL (with some XML) to generate an alert. My issue is, the onClick{ ... } function doesn't happen when I click the button. Everything else works fine, it's just this one issue fab.setOnClickListener { view -> alert { title = "Add Board" customView { include(R.layout.alert_xml) { this.spinner.adapter = adapter info("Alert loaded") val...

Kotlin kotlinClass.class.getName() cannot return package name but only simple class name AClass.class.getName(); if AClass is a java class, this method will return package name and class name. but when i convert AClass java file to Kotlin file ,it will only return a class name. so system cannot find this class path the code above

Combining Rx Singles into Observables recursively Let's say I have a Single called s_0 that can either emit an element t_0 from type T or fail (that would be a Single in some languages). That is: s_0: -- t_0 // Success OR s_0: -- X // Failure Instances from type T have a next() method that return an optional Single from type T as well (a Single? in Kotlin). This behavior leads to a chain of Single instances capable of emitting a chain of T instances, where each single s_i may emit an element t_i capable of returning...

what is difference between !! and ? in kotlin? I am new in kotlin, i want to know the difference between this two !! and ? in below code. i am having below two snippet first having use of !! for mCurrentDataset and another having ? for same variable. if(!mCurrentDataset!!.load(mDataSetString.get(mCurrentDataSelectionIndex), STORAGE_TYPE.STORAGE_APPRESOURCE)) { Log.d("MyActivity","Failed to load data.") return false } if(!mCurrentDataset?.load(mDataSetString.get(mCurrentDataSelectionIndex), STORAGE_TYPE.STORAGE_APPRESOURCE)!!)...

How to convert Swift code to skotlin? is there any way to convert swift code to skotlin. I am using this link https://github.com/angelolloqui/SwiftKotlin but unable to fix it.

How can I get a stable version of Android Studio 3.0 which includes Kotlin? How can I get a stable version of Android Studio 3.0 which includes Kotlin ?

returning the last expression in a block I am learning the new and very beautiful language Kotlin and everything seems to be very logical and consistent. I only found one thing which seems like an arbitrary exception to the rule than a solid rule. But maybe I lack enough understanding some deeper reasons behind the rule. I know that in if-else and when statements there are blocks of code, then the last expression is returned. In the next example 1 or 2 are returned depending on the condition - in our case it returns 1. val x = if...

Are there any resources for learning Kotlin as absolute beginners? I googled for resources but not satisfied. Found some books but all of them are paid. I was looking for tutorials like w3schools. Books or video tutorial will be also okay.

Error using an object for implementing an empty List I'm trying to rewrite the List interface as an exercise for learning Functional Programming in Kotlin, but I'm not able to figure out why I'm getting an error when I'm trying to have an object as the empty list, that doesn't occur in the Kotlin standard library. In my code, see below, I want to use NIL as a singleton empty list, using list() as the function to return it. However, this generates a type mismatch error on the function of type "Required List. Found NIL" interface List<A> {...

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What are the platform common classes in Kotlin? I'd like to use Kotlin to define interfaces between client and server. Currently, Kotlin can be used in 3 platforms: Java, Android, Web(JS). What Kotlin build-in classes can I use across all these platform? I would expect some common library dependency between kotlin-stdlib and <a href="https://mvnrepository.com/artifact/org.jetbrains.kotlin/kotlin-stdlib-js/1.1.2-4"...

Observer onChanged never called FooActivity.kt: class FooActivity : AppCompatActivity(), LifecycleRegistryOwner { override fun getLifecycle(): LifecycleRegistry { return LifecycleRegistry(this) } .. //

Why the code in an object expression can access variables from the scope that contains it in kotlin? In kotlin,the code in an object expression can access variables from the scope that contains it,just like the following code: fun countClicks(window: JComponent) { var clickCount = 0 var enterCount = 0 window.addMouseListener(object : MouseAdapter() { override fun mouseClicked(e: MouseEvent) { clickCount++ } override fun mouseEntered(e: MouseEvent) { enterCount++ } }) } But why?In java,it's not allowed to do this,because the life cycle of the...

How to convert ByteArray to String with specified charset in Kotlin I found there is a ByteArray.toString(charset:Charset) function in Kotlin,when I use that function in android studio IDE,it gets a syntax error. But I have tried the same code in Kotlin org site, it works well. How can I convert a ByteArray to String in Kotlin?

What is the reason for twitter4j.StreamListner IllegalAccessError IllegalAccessError in Kotlin? When implementing a twitter4j.StatusListner in Kotlin, the following code causes an IllegalAccessError: val twitterStream = TwitterStreamFactory().instance // See https://stackoverflow.com/questions/37672023/how-to-create-an-instance-of-anonymous-interface-in-kotlin/37672334 twitterStream.addListener(object : StatusListener { override fun onStatus(status: Status?) { if (emitter.isDisposed) { twitterStream.shutdown() } else { emitter.onNext(status)...

The error of inflating class fragment android kotlin So, firstly I answer at your question "Are you really? There are lots of answers on it.". Yes, I know, but I really try to resolve this problem like a third day: in all SOF there are no question on my error. I have 2 similar projects: in Java and in Kotlin. But this f@#^%!@ing error only in Kotlin. But XML is identity 100%. So, error is: android.view.InflateException: Binary XML file line #8: Error inflating class fragment. My activity_main.xml: What i tried to...

Why @Primary does not work for Kotlin classes sometimes? I have weirdest problem. I have Java class A and I also have Kotlin class KA which extends A, both are @Components, KA is also annotated with @Primary. In some components KA is autowired, in others A does. Actually it's even more weird than that, for the same dependent bean between different application launches sometimes KA gets autowired, sometimes A. If I rewrite KA in Java, then everything works as expected. Attribute name/constructor parameter name in all the dependent classes is the...

kotlin repeatable @annotations can't works on jdk-8 I have declared a repeatable annotation @Parameter in kotlin as below: @Repeatable annotation class Parameter(val name: String); but when I use it as below the compiler reports an Error: "Only annotations with SOURCE retention can be repeated on JVM version before 1.8". @Parameter("foo") @Parameter("bar") fun repeat() = 1; I'm sure I'm working with jdk-8 in...

kotlin.js.Promise usage kotlin.js.Promise has function then with declaration: open fun then( onFulfilled: (T) -> S, onRejected: (Throwable) -> S = definedExternally ): Promise I have two functions a() and b(), they returns Promise. (They represents some requests to the server.) I need to combine them and create new function like: fun c(): Promise { a().then({ b() }) } But it is not possible, because return type is Promise< Promise< Int > > and not Promise< Int>. I think in javascript...

Custom sonar plugin: newIssues not saved Heyho, I have my sonar-kotlin-plugin up and running. My RuleDefinitions are dislayed on the Rules-page, but when analyzing some kotlin projects the found issues are not saved. My sensor-issue-adding-code looks like this: private fun projectIssues(detektion: Detektion, context: SensorContext) { val fileSystem = context.fileSystem() val baseDir = fileSystem.baseDir() val predicates = fileSystem.predicates() detektion.findings.forEach { _, findings -> findings.forEach...

How to cast List of items to List of base items? This is base item: open class BaseItem {} and it's child class: class Item: BaseItem() {} Here is method which takes list of base items: fun doSomething(items: List) {} Now assuming that there is access to list of items, how to cast it without warning to list of base items? val items = ArrayList() ... items.add(someItem) ... doSomething(items as List)

Impossible to use Kotlin classes of a Maven dependency project I have a Spring boot app based on Kotlin (maven project called 'A'). Let's say this dependency contains a class A.MyClass In a second Maven project (called 'B'), I am importing the A dependency. However, I am not able to use any classes of the A project due to the following error: Unresolved reference: A.MyClass However, in a third maven project (called 'C') which is this time a Maven project based on Java 8, I am able to reference A.MyClass. The maven dependency:tree command in project...

Initializing a RecyclerView with Android Data Binding in Kotlin is throwing an error. What am I doing wrong? Description I am trying to set up an Android screen in Kotlin with a RecyclerView using android data binding. I have an activity that contains a fragment and the fragment contains a RecyclerView that I initialize with data binding. The issue is that when I try to set my recycler view's layout manager the application throws an IllegalStateException complaining that the specified child (I'm assuming it means either the RecyclerView or the LayoutManager) already has a parent and that I need to...

named functions vs lambda reflexion I am still learning Kotlin and trying to understand its core principles. What I do not get is this: fun x() : Int { return 10 } val y : () -> Int = ::x val z : () -> Int = { 10 } fun main(args: Array) { println(::x) println(y) println(z) } we get the following output: fun x(): kotlin.Int fun x(): kotlin.Int () -> kotlin.Int My question is why the output is not the same (I believed these functions should be interchangeable, equivalent)? I think the type of all the...

Null safety in legacy Java libraries used in Kotlin pojects Let's say I have particular code in old/legacy Java library: public class JavaClass { private String notNullString; private String nullableString; private String unannotatedString; public JavaClass(@NotNull String notNullString, @Nullable String nullableString, String unannotatedString) { this.notNullString = notNullString; this.nullableString = nullableString; this.unannotatedString = unannotatedString;...

annotation site-target confused me I use the annotation site target @get that confused me for a while. class GetSiteTarget1(@get:Annotation val value: Int = 1); class GetSiteTarget2 { val value = 1 @Annotation get () { return field; } }; both classes above with different result: GetSiteTarget1::value.getter.annotations; // not has @Annotation GetSiteTarget1::value.getter.javaMethod!!.annotations // has @Annotation GetSiteTarget2::value.getter.annotations; // has @Annotation...

In Kotlin, how can I work around the inherited declarations clash when an enum class implements an interface? I define an enum class that implements Neo4j's RelationshipType: enum class MyRelationshipType : RelationshipType { // ... } I get the following error: Inherited platform declarations clash: The following declarations have the same JVM signature (name()Ljava/lang/String;): fun (): String fun name(): String I understand that both the name() method from the Enum class and the name() method from the RelationshipType interface have the same signature. This is not a problem in Java...

Is it practical to use Kotlin with Angular? Please upvote if you support good programming languages and platforms! :-) This might sound a bit over the top, but is there some practical way of using Kotlin with Angular 2+? I know of https://github.com/Kotlin/ts2kt to use typings in Kotlin. And I've seen on Google I/O 2017 that Kotlin has broader ambitions to support multiple platforms. But does it add up (or is there hope for) to using Kotlin with Angular 2+ in a...

How to embed for loops in Kotlin string templates We can easily nest expression operators like if and when in Kotlin string templates: "List ${if (list.isEmpty()) "is empty" else "has ${list.size} items"}." But for or while are not expressions and can't be nested in template like this: "${for (item in list) "$item"}" So I was looking for convinient ways to use loops inside large templates.

The best Kotlin book for getting started [on hold] I am currently programming android using Java but now google has announced a new programming language for working on android and that's Kotlin. as a beginner of the language which book will guide me well to get all the core points in the language well. I would be intereseted if it's even a blog or a website.. Anything?