Kotlin Destructuring when/if statement So I have a String i would want to check if I should split into two, or return some default value. Like this: val myString = "firstPart-secondPart" val (first, second) = when (myString.contains("-")) { true -> myString.split('-', limit = 2) else -> ??

RxKotlin with Socket.io in Android What I trying to do is listen to socket data and convert into an observable string that my UI can Subscribe this event and do Change on UI So far I created a class SocketConnection maintain in dagger connection happen properly and received data and able to do with interface correctly, but want to apply with rxkotlin. Using Socket.io,kotlin SocketConnection listener fun createMessageListener(): Observable { L.d("Inside function") return Observable.create { subscriber ->...

Why does Kotlin not automatically cast KFunction1 to Matcher in Hamkrest? Looking at Hamkrest's github, the matcher tests include this: fun isRipe(f: Fruit): Boolean = f.ripeness >= 0.5 fun isCookingApple(a: Apple): Boolean = a.forCooking ... val mA: Matcher = ::isRipe and ::isCookingApple However, when I replicate this code I get a compiler error: Error:(42, 45) Kotlin: Type mismatch: inferred type is KFunction1 but...

Not sure how to convert cursor to to this method return type I'm asking this question again 'cuz the provided answers are not compatible with the new version of Android Paging Library. My Dao function is as following @Query("SELECT * FROM items") fun getAll() : DataSource.Factory There's not a something different from the samples provided by google-developers but i keep getting the following error : error: Not sure how to convert a Cursor to this method's return type...

Guice TypeLiterals in Kotlin I have a scenario where I have a generic interface and wish to bind multiple implementations of that interface in Guice. Normally in Java this would mean TypeLiterals, how would this be done in Kotlin? bind(TypeLiteral(){}).to(RealResolver::class.java) This gives a compiler error of: cannot access : it is public/*package*/ in 'TypeLiteral' There is a TypeLiteral.get() method however I cannot seem to get that to work either

How to mock objects in Kotlin? I want to test a class that calls an object (static method call in java) but I'm not able to mock this object to avoid real method to be executed. object Foo { fun bar() { //Calls third party sdk here } } I've tried different options like Mockk, How to mock a Kotlin singleton object? and using PowerMock in the...

Kotlin Data Class packaging Kotlin introduces the wonderful concept of Data Classes. These classes will derive the equals()/hashCode(), toString(), getters()/setters(), and a copy() function based on the properties declared in the constructor: data class KotlinUser(val name: String, val age: Int) In Java, this would look something like: public class JavaUser { public User(String name, Int age) { ... } //getters //setters //equals()/hashCode() //toString() } My question is about the...

Edit pdf with external application programatically I have a request to make my application edit PDF files. Because i found it hard to integrate into the application, i decided to go with the external app and decided to use Xodo reader. The problem i am having is that when my pdf is opened in the Xodo app and edited, it's not being saved to its original location, but rather a copy is saved to the Download folder. To me, this...

Error: Unresolved reference: DaggerAppComponent I've been facing this problem for 3 hours. I couldn't find any logical reason to what is happening. The problem is, Only when I use the generated Dagger classes, and after Gradle do the Build every reference to these classes became red and I get the error: Error: Unresolved reference: DaggerAppComponent But, If I comment out every line in the App class reference any of these generated Dagger classes. The build process completed successfully. I tried doing clean/ rebuild/ make project....

Inheritance from Java class with a public method accepting a protected class in Kotlin I have this situation: There are a Java class public class A { public void overrideMe(B param){ //TODO: override me in Kotlin! } protected static class B { } } and a Kotlin class, which inherits from it and has to override method "overrideMe" class K: A() { override fun overrideMe(param: B) { println("Wow!") } } But Kotlin doesn't allow this behaviour. 'public' function exposes its 'protected (in A)' parameter type B Is there any way how...

Gatling integration with Corda/Kotlin project I want to use Gatling for performance testing on my Corda project (coded in Kotlin), wanted to know what dependencies to add in build.gradle and maybe a skeleton function code for testing. I have API endpoints (POST mostly) that I would need to hit for the performance testing - they take in JSON code in). Many thanks!

kotlin httpservletrequest object to string When converting http servlet request object to string, I am always getting a "" string. This is my code. ```private fun getBody(request: HttpServletRequest): String { var inputAsString = "" try { var inputStream: InputStream = request.inputStream if (inputStream != null) { inputAsString = inputStream.bufferedReader().use { it.readText() } } } catch (ex: IOException) {...

Kotlin annotation processors sometimes work without explicitly applying `kapt` plugin This is a follow up question to this duplicate question I was using Android Room without explicitly applying the kaptplugin to the Gradle build file. apply plugin: 'kotlin-kapt' Everything was working just fine, until I started using Dagger2, I couldn't reference the generated Dagger file. It turns out that annotation processors worked without explicitly applying the kotlin-kapt plugin...

Android - Cannot create instance of abstract class error [duplicate] This question already has an answer here: Android support library 27, Fragment update? 1 answer After updating the targetSdkVersion and compileSdkVersion from 26 to 27, Android Studio had issues with how I was using context in a few of my fragments. Specifically, it said, "required...

buildSrc folder to organize an Android/Kotlin project dependencies/metadata Following Google's recommendation of using extra properties to share them through your project, I came across a nice solution based on buildSrc + Kotlin gradle script for my Android/Kotlin projects. This solution provides me very nice advantages comparing to the other classic approach of having multiple Groovy written build.gradle files per module (plus the root one) with their dependencies, parameters. The main ones are: Using kotlin syntax. Compilation errors. Auto-completion. Click...

How do I make a nested list in Dokka? Trying to document some Kotlin code with a pretty routine structure: A numbered list. With a bulleted sublist. Where the numbers continue correctly at the top level of the list. What I take to be the official Dokka page doesn't even have the word "list" on the page. Have Googled hither and yon without finding any info on how to do this. Help!

setting resource id to spannable in kotlin i want to give each span a resource id that i could access to apply tooltip view on. the issue i'm facing is that any tooltip that i try to add to textview centers to the view, i'd like a tooltip exactly on the particular span i tap. again, all i need is a solution to attach the anchor point of any tooltip library to a span and not a textview itself. here's the code of what i tried and failed at so far. fun tooltipAndDots(desc: Any?, arabicWordsString:Any?, translationsString:Any?,...

Unable to merge dex in Android Studio when building app I am receiving this error in Android Studio: Error:Execution failed for task 'apptransformDexArchiveWithExternalLibsDexMergerForDebug'.

com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex

With this app gradle file: apply plugin: 'com.android.application' apply plugin: 'kotlin-android' android { compileSdkVersion 26 buildToolsVersion "26.0.3" defaultConfig { applicationId "com.example.android.kotlintest" minSdkVersion 23...

Kotlin + Maven can not find main class when running packaged jar I am trying to package(maven package) and run(java -jar file.jar) a project that contains both java and kotlin code. I have followed the tutorial at: https://michaelrice.com/2016/08/hello-world-with-kotlin-and-maven/ kotlin source src/main/kotlin java source src/main/java the file I am trying to run is located in src/main/kotlin/THEFILE.kt After succesfull packaging trying to run the...

SQLiteException near "." while saving image Android Yes, another SQLiteException, I did search around, I swear. Anyway I've an Android app that takes pictures and saves them to a custom folder in DCIM. When saving the picture, I get an SQLiteException near ".". Really struggling to find the error here. Here's the method setting up the file: reader = ImageReader.newInstance(largest.width, largest.height, ImageFormat.JPEG, 2).apply { setOnImageAvailableListener({ // todo 2018/02/21 -- refactor this into separate...

Why should Always use immutable collection interfaces to declare collections which are not mutated in Kotlin? I'm reading Kotlin docs. At Immutability sector, they comment below. I wonder why should we do that? When I tried the example code, it act the same. Immutability Prefer using immutable data to mutable. Always declare local variables and properties as val rather than var if they are not modified after initialization. Always use immutable collection interfaces ( Collection , List , Set , Map ) to declare collections which are not mutated. When using factory functions to...

Kotlin invoke constructor using reflection For a simple machine language reader, I have a number of classes aaaInstruction, bbbInstruction, cccInstruction, etc. which are invoked as aaaInstruction(v1, v2, v3). The idea is that the input is given in the form: aaa v1 v2 v3 bbb v1 v2 v3 ccc v1 v2 v3 In the main class I use the code: var input = Scanner(System.in) val instcode = input.next() val cname: String = instcode.capitalize()+"Instruction" How can I then invoke cname(v1,v2,v3)?

At what point should a Android Programmer learn Kotlin [on hold] I am a beginner Android Programmer, I've been at it for a few months. Should I be thinking of learning basic Kotlin coding, or should I consider it a more advanced step after I have mastered basic Android JAVA syntax? At what point should I consider learning Kotlin?

How to get my flutter app to realize that it was started with a different intent? I have a Flutter app which, like a browser, can be started from either the launcher or through a URI intent. I have two files. The Dart file containing the main code and the Kotlin file containing the intent catching code. My Kotlin code looks like: class MainActivity : FlutterActivity() { override fun onResume() { super.onResume() print("got at resume ${intent.data}") } override fun onCreate(savedInstanceState: Bundle?) {...

Only specific lambdas or arguments should be inline while creating inline function in kotlin While using inline functions, kotlin will inlined all things. Like function and arguments or lambdas which passed in function. Example: inline fun myFun(getUserName: () -> String, getUserMobile: () -> String): T { // ... } Here in above example, getUserName() and getUserMobile() both will be inlined because we declare myFun as inline function. As per kotlin doc: The inline modifier affects both the function itself and the lambdas passed to it: all of those will be inlined into...

React native component crashes on not using PersistableBundle in onCreate android I am creating on chat app in React native which is to be open from Native Android activity. My Activity, ChatActivity was initially developed with onCreate PersistableBundle as follows: override fun onCreate(savedInstanceState: Bundle?, persistentState: PersistableBundle?) { super.onCreate(savedInstanceState, persistentState) mReactRootView = ReactRootView(this) mReactInstanceManager = ReactInstanceManager.builder() .setApplication(application)...

How can I set layout_weight to radio button in Anko DSL (Android)? I've tried following way: radioButton { id = RADIO_SECOND text = "second(s)" }.lparams(width = wrapContent, height = wrapContent, weight = 0.25F) But it gives error Error:(107, 19) 'inline fun RadioButton.lparams(width: Int = ..., height: Int = ..., weight: Float): RadioButton' can't be called in this context by implicit receiver. Use the explicit one if necessary. How can I proceed?

Combining Java8 + Kotlin on appengine build with Maven I have working multi service project on appengine standart written in Java8. I would like to start using Kotlin in same project too. In fact mixing java and Kotlin in individual services/modules. I use Maven for build and deploy. Pls does anybody combine this? I was looking for exmples but or it was pure Kotlin or it used gradle.. I am not familiar with gradle :(. I do understand I need to make kotlin folder aside java folder in main. But not sure on dependences and other modifications in...

Proguard can't process this simple code I’ve found the problem in my codebase and I’ve tried to simplify it to the following snippet: class DemoProguardIssue { fun main() { with(Unit) { runLambda { runLambda { } } } } private fun runLambda(lambda: () -> Unit) = lambda() } Proguard complains with this error and breaks my build Warning: com.example.DemoProguardIssue$main$1$1$1: can't find referenced class...

Fatal Exception: kotlin.KotlinNullPointerException on some devices After I changed my code on my app from sync task to async task, begin to crash in some devices. What causing that? How can I fix that and remain async? Here is the crash log from Crashlytics: Fatal Exception: kotlin.KotlinNullPointerException com.example.myapp.news.NewsTweets.SetupTwtr (NewsTweets.kt:234) com.example.myapp.news.NewsTweets$onCreateView$1.success (NewsTweets.kt:89) com.twitter.sdk.android.tweetui.BaseTimeline$TweetsCallback.success (BaseTimeline.java:63)...