Is the method addRound thread safe in the below snippet? data class Game private constructor( val id: UUID, val host: Player, val rival: Player? = null, val rounds: List = emptyList() ) { companion object { fun create(host: Player): Game { return Game(id = UUID.randomUUID(), host = host) } fun addRound(game: Game, roundType: RoundType): Game { val newRound = RoundFactory.create(roundType = roundType, gameId = game.id) return game.copy(rounds = listOf(game.rounds.toList(), newRound) as List) } } }...

What is the best way to execute asynchronous code inside CameraX analyze()? I'm using CameraX's image analysis use case that keeps calling the analyze() method in my custom Analyzer class. Inside analyze(), before doing anything else, I need to send a request to a connected device and wait for its response; the latency is very low and I'm already doing it synchronously with no issues, but I was told it's better to make it asynchronous just in case the device responds too slowly. I know that MLKit's process() returns a Task and I already call onSuccessListener { } on...

Flutter: Building Android app does not work - Main Activity Missing Java/Kotlin I am a bit frustrated I build a crypto converter app and it works on my phone in the release mode and with flutter build apk I was also able to create and APK and also install on my phone. All good sofar. But now I want to publish for Android Playstore and there are couple of steps I need to follow and one is update the MainActivity File. But for me it shows everywhere error and I dont know why. I have also a Kotlin folder and java folder. See below. Thank you for your help! <a...

How create string array from single string in Kotlin I have a string line from EditText, all words separated from each other by comma just like this: "Some, string, words, bla-bla" And I need to create array from this string, each element would be separate: "Some", "string", "words", "bla-bla" So, I saw how it was done on Java here but idk how convert it to kotlin, as I know Kotlin doesn't have split operator This array I will save in...

Running two Countdown Timers Sequentially I'm a Kotlin newbee. I am trying to program a countdown timer for an archery countdown clock. First the countdown timer countDownP runs for 10 sec, then runs countdown timer countDown for 60 sec. However the two timers won't run sequentially unless I nest the 2nd timer inside the onFinish() of the 1st timer. Any suggestions would be most appreciated. Here's the code import ... class MainActivity : AppCompatActivity() { //initialize clock countdown timers for prep and shoot internal...

Extract efficiently a Sub-List of Files from List&lt;Files&gt; with a list of names I have a HUGE list of Files List (1 Giga) and a small list of file names List, around 20 file names. Now I want to extract the sublist of Files that contains only the files from the other list, the list of file names. What is the most elegant and efficient way to do it in Kotlin in a Kotlin way.

Go to another activity on Menu Item Selection Kotlin Hello I have problem with going to another activity by MenuItem. I don't where is the problem with my code, because Android Studio tell that is problem with intent. I Imported intent already at the bottom of kotlin class. I saw tutorials, but there is still a problem with a code. override fun onOptionsItemSelected(item: MenuItem): Boolean { return super.onOptionsItemSelected(item) val id = item.itemId if (id == R.id.btn_settings) { Intent intent = new...

Using an Interface twice in the same activity Just to let you know, I am quite new to Kotlin, but I have a good experience with Java. I have two recycler views in an activity, with the same adapter, but different behaviour. In Java, just create an interface in the adapter class and override it using a method setOnItemClick(OnClick onClick), but in Kotlin, things seems to be different. I saw people overriding the interface in the activity, and that will serve only as one behaviour ... Any suggestions ?

How to return failed task result in continuation task I'm writing my first app in Kotlin and am using Firestore & Firebase Storage. In the process of deleting a document I want to delete all files in Storage that the document references (as it is the only reference to them in my case). If the Storage delete fails, I want to abort the document delete, in order to avoid orphan files in my Storage. I also want to do everything in "one Task", to allow showing a progress bar properly. My simplified code looks like: fun deleteItem(id: String):...

How do I make a data class property transient in Kotlin and Spring Boot? I have a data class like this: @Entity @Table data class Student( @Id @SequenceGenerator(name = "student_sequence", sequenceName = "student_sequence", allocationSize = 1) @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "student_sequence") var id: Long? = null, val name: String, val email: String, val dateOfBirth: LocalDate, val age: Int, ) Since I have dateOfBirth, I can just calculate the age from it, so I want to make it transient. Thing is,...

Mockk unmockk() method is not destroying mocks I am running the following test code, but in some weird way I am not understanding it is not clearing the mocks in between the two tests. I am getting environmentAsRequired as a return of repo.getClusterEnvironment(environmentName) on the second test instead of it throwing NoResultException() which causes the second test to fail because the exception I am asserting does not get thrown. I have already verified and the method annotated with @BeforeEach is being called in between tests. Anyone...

Null pointer exception when trying to pass data between fragments I'm trying to pass data between a fragment to another fragment trough the main_activity. While doing so, I can see that it works (thanks to Log.d(...)) but right after my value becomes null and I get an null pointer exception my code MAIN_ACTIVITY: class MainActivity : AppCompatActivity(), Communicator { private lateinit var binding: ActivityMainBinding override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) binding =...

kotlin classDiscriminator/typed serialization without a sealed class I can't seem to figure out how to get typed serialization without a sealed class. I would like a regular abstract class to be polymorphic and implemented by a bunch of classes. In the polymorphism doc I can see that using a sealed class would work, but I don't have the liberty of putting all of these classes in the same file. Example code: @Serializable abstract class AbstractAttribute : Attribute { constructor(_value: T, _source: Source) { value = _value source =...

How to migrate this mutlipart file upload to Spring Boot 2.4? With Spring Boot 2.3 I was using the following Kotlin code val mvcResultImage = this.mockMvc!!.perform(MockMvcRequestBuilders.multipart("/somepath) .file("files[]", imageFile.getBytes()) .characterEncoding("UTF-8")) .andReturn() in an integration test for a controller with a function @PostMapping(path = ["/somepath"], consumes = [MediaType.MULTIPART_FORM_DATA_VALUE], produces = [MediaType.APPLICATION_JSON_VALUE]) @ResponseBody fun...

Download html content generated by js in Android To download the html content, I used: URL("my_url").readText() It used to work well until the current website update that shows "Loading..." before generating its contents. As the result, the previous code only gets "Loading..." instead of actual content. Any solution for this situation? Thanks

Kotlin - is it possible to infer generics type parameter? Given this code: // Can generic type parameter be inferred? class Foo { fun consume(p: T) { println("slurp $p") } } //region abstract class ATestsOfFoo(private val foo: U) { fun test1() { foo.consume(someT()) } abstract fun someT(): T } class TestsOfFoo(foo: Foo): ATestsOfFoo(foo) { override fun someT(): String { return "Hello" } } val testsOfFoo = TestsOfFoo(Foo()) testsOfFoo.test1() //endregion I'm looking for a way to infer T type...

Change image picker theme Is it possible change the image picker to dark mode? I call it from Kotlin app like so: startActivityForResult( Intent(Intent.ACTION_PICK, MediaStore.Images.Media.INTERNAL_CONTENT_URI), RC_PICK_IMAGE )

Display different frames of the video every second I have this recycler view filled with file information. These files are videos so I display a thumbnail and their name. What I want to do is to be able to show 3 frames of the video, that changes every second. For example if this video is 20 seconds long I'll display a frame of second 6, second 12, and second 18. Well I have tried to do this and the result was pretty much very bad. For every video I have to get 3 frames and this is tedious and very slow and obvious recycler view gets lagged...

Theme.MaterialComponents style ruins Firebase AuthUI layout I am writing my first app in kotlin and am using FirebaseAuth & AuthUI for authentication. My login screen works perfectly, and looked like: Now I am trying to change my AppTheme's parent to "Theme.MaterialComponents.NoActionBar" (from "Theme.AppCompat.NoActionBar") but the login screen changed to: I call the login screen like so:...

How do I pass the variables of an activity to the fragments of a BottomNavigationView? I am very new to taking an android application and for a project I need a BottomNavigati but I cannot get my data that comes from the beginning of the session to pass to the main fragment Activity: val bundle1 = Bundle() bundle1.putString("User",User) bundle1.putString("Correo",Correo) bundle1.putString("Region",Region) val navView: BottomNavigationView = findViewById(R.id.nav_view) val navHostFragment = supportFragmentManager.findFragmentById(R.id.nav_host_fragment) as...

How to chose view name when code with synthetic or viewbinding in kotlin? When I code with synthetic or viewbinding, view's name in xml always bother me. Because code will gather view's name in var variable. (And I know use import * as * will keep two different name, but it's another trouble.) In view binding demo page:https://developer.android.com/topic/libraries/view-binding#activities View's name in xml is simple and not splite with underline. So,...

Call Android share intent from JavaScript in webView I am trying to use the code of this article to launch the share intent of my Android app (kotlin) from a JavaScript in a webView. Here is the code I use to start: class MainActivity : AppCompatActivity() { object AndroidJSInterface { @JavascriptInterface fun onClicked() { Log.d("HelpButton", "Help button clicked") } } override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) val webViewClient = object : WebViewClient() {...

I'm trying to create viewpager that can slidable to right to left. How to add item to list of viewpager adapter? I'm trying to create a viewpager that can add item step by step to slide. In normal case I would add item to end of list then ı can invoke notifyDataSetChanged. But my app is calendar app alike. So you can't slide it after than today. I want to slidable from this day to past. When I do this, I want to use pagination cause there are a lot of datas to retrieve. And I know RTL is not a good solution. What would you do in this case?

Why the ViewModel does not store information in RecyclerView? Please, help ! I need to make my 5 items appear in the recyclerView and when the delete button is pressed, they are removed. Also, when i rotate the screen, everything should be saved. So they came to my problem. When i rotate the screen, the list is reloaded. Everything I deleted was erased. (Activity destroyed): (( I decided to do it through ViewModel. And for the second day I have been sitting and cannot understand what the mistake is. Why is my code not working? It is advisable to write a...

Simulating uploading a file in chunks to the Cloud: Why doesn't my flow commence despite using collect()? I am implementing a service that will upload files to Azure Blob Services using their SDK for Java (v12). The uploadFile() method in the SDK requires a Flux for the content of the blob. I have implemented a service that is based on Kotlin Coroutine Flows. It receives a file upload request, which contains a Flow and other items. It does some minor transformations and then sends the flow object to another method that performs the uploadFile() using the SDK. The issue that I am having is that...

Android Volley weird error trying to upload an image to a server I am converting an image to Base64 and then trying to upload same image to Server using Volley library and here is the method, I have written to achieve same private fun remoteUpload() { Log.d("called...", "remoteUpload") val stringRequest = object : StringRequest( Method.POST, urlUpload, Response.Listener { response -> makeText(applicationContext, "Success", Toast.LENGTH_SHORT).show() }, Response.ErrorListener { error ->...

recyclerview with different item size and itemcount I use a recycler view to display 3 to 11 items. Now to do this,how to put these items in different sizes without creating layout for any number of items.

Kotlin define extension property on Map via Delegation In the following code snippet DelegatingMap is a MutableMap. As per the Kotlin documentation I can define a map in a object and have extension properties on the map. Why does the following code not work? private val DelegatingMap.test: String by this Error "this is not defined in this context" Remember, this is a MutableMap. I "solved" it using the following...

Which Kotlin Coroutine data source (Channel, Flow,...) to use? I'm writting a messaging app (like whatsapp,...) for Android and I'm currently lost what is the best primitive to use from a lot of stuff released with latest coroutines. Would be grateful for some advice what to use (Channel, Actor, Flow, ChannelFlow,...) for queue implementation described in point 3 and 4. My flow is like that: User send a message Message is stored to DB (Room). So if app is killed message is not lost. Message is also offered to queue. What to use here (Actor, Channel,...

Cant find reference for button, kotlin library I just have this: package com.example.world import androidx.appcompat.app.AppCompatActivity import android.os.Bundle import android.widget.Button class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) button.setOnClickListener() { // Do some work here } } } But on this line: button.setOnClickListener() { // Do...