Slight lag using button setOnTouchListener I am working on a project that requires the exact moment a button was touched to be recorded. For this, I am using setOnTouchListener. I have simplified the listener down to a simple print statement. Within Logcat, there is a very slight delay between when the button is touched, and when "TOUCHED" gets printed. class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState)...

How do I read different input formats from scanner in Kotlin? I am new Kotlin learner in JetBrainsAcademy. I want to know how can I read different input formats by using Scanner class in one code. Before I used Scanner only for simple input format, i.e.: 1)triangle a b c But now I need to solve the problem with three kinds of formats simultaneously my homework page, i.e.: 1)triangle a b c 2)rectangle a b 3)circle r Of course code below doesn't work. What...

Kotlin form of Scala multiple _ [underscore] magic In Scala _ [underscore] magic Anantha Kumaran uses + as a shorten version of (a,b)=>a+b. In Kotlin Koans -- SAM conversions there is a similar bit of code x, y -> y - x. Is there a short version of...

Can't delete Integer from ArrayList I'm trying to create an Android App which uses Android Room as it's Database. I have linked two tables via their ids. If i check, whether the parent should be destroyed (because there is no child left), I come across an error with an ArrayList, that contains those child ids. I can't remove the id integer from the ArrayList of the parent. IdList.contains(childId) returns false Logging all integers in the IdList shows that the childId is in the IdList IdList.indexOf(childId) returns the right...

Wrapping AsynchronousSocketChannel in BufferedInputStream What is the difference between wrapping an AsynchronousSocketChannel and SocketChannel in a BufferedInputStream? Is the behavior the same in both cases? val inputStream = BufferedInputStream(Channels.newInputStream(aynchronousSocketChannel)) inputStream.read() vs val inputStream = BufferedInputStream(socketChannel.socket().getInputStream()) inputStream.read()

Calculate midpoint between of locations with accurate result I need a midpoint between locations to show our restaurant, I had tried this but this was not accurate :( Please share any accurate code or reference of any API private fun computeCentroid(points: List): LatLng { var latitude = 0.0 var longitude = 0.0 val n = points.size for (point in points) { latitude += point.latitude longitude += point.longitude } val builder = LatLngBounds.builder() return LatLng(latitude / n, longitude / n) }

Kotlin and Klaxon - Possible to validate JSON to handle nulls I've just started using Kotlin and Klaxon to parse and create some JSON. As a start I've got the following code: class StartModel(val id: String, val s3Path: String) Then val parsedInput = Klaxon().parse(someJsonString) val result = StartModel(parsedInput.id, parsedInput.s3Path) Now what IntelliJ/Kotlin rightly complains only safe (?.) or non asserted calls are allowed. From my reading I know I can get rid of that message by doing: class StartModel(val id: String?, val s3Path:...

How should I go about recreating this kind of effect on an Android CardView? I'm trying to recreate this colored drop shadow on the CardViews in my app: This is what I've got right now: Basically just a LinearLayout with a bunch of CardViews. If possible, I'd like to be able to influence it with the cardElevation attribute, since I've implemented for when...

Kotlin Spring Reactive Webflux - Handle WebClient Error I am having troubles trying to handle different errors from calling Spring webflux's web client. Below is my current code. return request .bodyToMono(InputMessage::class.java) .flatMap { inputMessage -> client .get() .uri { builder -> builder.path("/message") .queryParam("message", inputMessage.message)...

Android checkbox remove the box keep the text I am using a custom background color that changes depending on the state of the checkbox so my background property is already used. Most advices tell me to set the background to @null. I just want to keep the text and remove the box on the left. I can already change the color of the background and the color of the text. I just want to remove the box. <a href="" rel="nofollow...

Android Studio Kotlin How to print strings and where do they appear I did see the question before on "How to print to console"... I am coming from iOS/Xcode to where there is one place where all outputs and errors appear so it is a bit confusing how in android studio there are multiple places for multiple out puts. print("HELLO TRYING TO PRINT") Log.d("PRINT", "Printing this message") I have tried these yet even in "Console" and switch it to "Debug" and try searching "PRINT" or "Printing this message" it does not appear. I am using a Samsung Note 8 to run...

Does Spring have Jackson built in - If so how to parse JSON I've creating a Spring Boot application. I've been told, Spring comes with Jackson - however every tutorial I'm seeing, shows adding it as a dependency. I want to parse and create some JSON - is there a clear guide on how to do this - with using whatever is in Spring? Thanks.

Android, Kotlin, ContentResolver: Image viewers do not recognize content uri my app has sent I want to make my app: 1.1. Convert "file:///storage/emulated/0/a/picture.jpg" to content:// URI 1.2. Create Intent and send to image viewer with content:// URI 1.3. So image viewer should open and show /storage/emulated/0/a/picture.jpg So I wrote some code: fun AShortStory() { var Amy = getContentResolver().query( MediaStore.Files.getContentUri("external"), arrayOf(MediaStore.Files.FileColumns._ID, MediaStore.Files.FileColumns.MIME_TYPE),...

Why is declaredFields including $change and serialVersionUID In my android project I'm trying to loop through all the fields of a class using reflection, however, the result of declaredFields includes two unexpected fields, $change and serialVersionUID which aren't defined in the class This is in an android project using a Kotlin data class. I've tried looking up the two fields in question and have seen that serialVersionUID seems to relate to classes which extend serialisable (<a...

RecycleView not scrolling val addressesLayoutManager = LinearLayoutManager(context) addressesLayoutManager.orientation = RecyclerView.VERTICAL addressesRv.layoutManager = addressesLayoutManager addressesRv recycleView is not scrolling. I have this set in a bottomsheet dialog. It is just taking the 200dp height size and show only the items that fit, and I can not scroll through all items. I have tried to take out the CardView, to remove the other recycle in the view, to wrap addressesRv inside a...

How enable auto rotation to Fresco ImageViewer? I need when the device is rotate the ImageViewer of Fresco rotate same.

Are Thymeleaf model attributes not allowed to start with 'is'? So I'm writing a springboot application and came across a weird behaviour: If a property name start with is, for example: isIgnoreRequest thymeleaf won't find it but if i change it to ignoreRequest it works. So my question is: Am I not allowed to have is at the beginning? Here is some more context: data class Response(val isIgnoreRequest: Boolean = false, val name: String = StringUtils.EMPTY) ... //This is how I add the attribute //Info = Response object...

RxJava what's difference Observable.just vs Observable.fromCallable? I have a question about the difference between Observable.just and Observable.fromCallable. I have a "service" class like this: class Service { var cachedToken: String = "" get() { if (needToRefreshToken()) { refresh() // Can throw Exception!!! } return token } } And below code is calling upper code like: Observable.just(service.cachedToken) .subscribeOn(ioScheduler) .observeOn(uiScheduler)...

Spring Boot and Kotlin - How to validate a JSON object I'm using Spring Boot in Kotlin. I'm taking in some JSON string, parsing it with ObjectMapper however I want to validate it has everything as in per the model - namely id and s3FilePath are not blank or missing. So this is the model I want to validate against: @JsonIgnoreProperties(ignoreUnknown = true) class MyModel { var id : String = "" var s3FilePath : String = "" } This is where I use that model: class FirstMessage { fun create(newMessage: String) : String {...

Not able to access parent class variable in child class in kotlin In kotlin I am trying to use parent class variables in child class but I am not able to use them ,as I am new to kotlin I don't understand how to do it simply I am trying to access sharedPerfernces and getting but its giving me null class webViewActivity : AppCompatActivity{ internal var shared_preferences: SharedPreferences? = null override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) shared_preferences =...

How to handle Pending intent from notification If I have an application with have A -> B -> C -> D in stack. How could I open an activity from Notification and make stack become A -> B -> C -> D -> E And if application is terminated, how could I open application from notification like open E activity from notification but prevent it from launch when open application again [For example, I open E activity then I backpress to exit an application then when I open application again I want it to open A activity(Root Activity) instead...

Android Kotlin - Webview Database My webview is loading the url because it need database enabled. I tried the code below. it's working on devices higher then API 19 but android 4.4.4 not working for me webview.settings.javaScriptEnabled = true // webview.webChromeClient = WebChromeClient() //webview.webViewClient = WebViewClient() webview.settings.setSupportZoom(false) webview.settings.builtInZoomControls = false webview.settings.domStorageEnabled = true...

min-Sdk does not work besides the device with the latest API(29) I built a project with compileSdkVersion 29 and buildToolsVersion "29.0.0" . When I set minSdkVersion 21 and tried to run the project with Nexus S(API 21) and Nexus 5X (API 26). It did not work at all. Only when I run the project with the latest API(29), it works. Would you teach me how I should use minSdkVersion properly? "built.gradle(Module: app)" android { compileSdkVersion 29 buildToolsVersion "29.0.0" defaultConfig { applicationId "" minSdkVersion 21...

Multiplatform library with native library I'm trying to create a multiplatform library for kotlin, and I wanna do it with a native cinterop(ted) library. I'm importing it into gradle, and it loads, if I change commonMain to Native, library loads, otherwise it's just red. Is what I'm trying to do even possible at this time? Can we import native (cinteropted) libraries into common kotlin? I'm adding my gradle file at the bottom (Kotlin DSL) plugins { id("org.jetbrains.kotlin.multiplatform").version("1.3.41")...

Android Recycler Pagination : Room + RxJava + MVP I'm new to RxJava, I've been reading so many articles about this subject and I've well understood the concepts of reactive programming in general and RxJava operators for room specifically. Most of the apps I build rely on MVP architecture, Where the presenter is responsible of binding the ViewHolders, In this case, the RecyclerViewAdapter knows only about items count, and then it asks the presenter to bind each item based on it's list position. Here's a binding code example : override fun...

Android Webview - iframe content not loading, or loading incorrectly I have a webview inside a recyclerview. I am loading a html string inside this webview. But some content in iFrame is not loading correctly. While the same content is loading normally iOS. Mainly PDF files that are embedded in the html content. Webview code : mWebView?.settings?.javaScriptEnabled = true mWebView?.settings?.loadWithOverviewMode = true mWebView?.settings?.allowFileAccessFromFileURLs = true mWebView?.settings?.allowUniversalAccessFromFileURLs = true...

Why do we need atomic boolean when overriding call adapter? I am watching one of the google android samples, and I am having a hard time what exactly the variable started is supposed to do. Here is the class.

Is there any difference in null checking quality between `?.apply`, `?.run` and `?.let` in Kotlin? I know the convention is to use ?.let for null checking mutable variables because ?.let will make sure that the variable we're checking doesn't change to null in the middle of the block that's being executed. Will the same hold true for ?.apply and ?.run? One last thing, if the variable is immutable is it recommended to just use a simple if?

Does Kotlin has a keyword `None`, like Python? I use python almost everyday. Now I am learning Kotlin. I wonder if there is None in Kotlin so that we can do something like: v1 = None if v1 is None: pass # then we do something I did some research, and I found there is none in kotlin-stdlib/kotlin.collection, but that does not seems to be something I am looking for. If there is such keyword like None in Kotlin, how can it be used? If not, how does Kotlin deal with the situation like the code shown above?

ViewHolder: How to get context inside bind() function of Groupie RecyclerView Library? I'm showing a List of users in my Firebase Database using the popular Groupie Library to generate the Recycler View. Inside the ViewHolder class's bind() [onBindViewHolder() without using Groupie], I'm trying to get the Dominant Color from the Palette created from the user's Profile Image & set that color as the Imageview's Shadow Color. However, to use the palette, I need to provide context in the palette.getDominantColor(ContextCompat.getColor(context, R.color.defaultColor)) Problem...